Final Report Summary - GRAIN (Greener Aeronautics International Networking)
Executive Summary:
Greener Aeronautics International Network (GRAIN) is a 'Cooperation and Support Action' project which comes from the effort done in AEROCHINA and AEROCHINA 2 projects. AEROCHINA1&2 have been networking projects co-funded by FP7 and AVIC (China) and coordinated by CIMNE.
Background
The continuous increase of air passenger transport generates an increasing use of hydrocarbon fuel with excessive emission of CO2 and NOX (greenhouse gases and pollutants and noise). It is well known that commercial aircraft operations impact the atmosphere by the emissions of greenhouse gases and greenhouse gas precursors and also through the formation of contrails and cirrus clouds. The EC has published in 2000 the future of aeronautics in the ACARE Vision 2020 containing the ambitious goals on the environmental impact with 80% reduction in NOX emissions, 50% reduction in CO2 emissions per passenger kilometre, and the reduction of the noise in by 20dB (50% reduction on the perceived noise). To achieve the ACARE Vision 2020 goals green aeronautics technologies will play a more and more dominant role. GRAIN Supported Action, based on the same collaborative and win-win spirit introduced in former EU-China AEROCHINA 1 & 2 projects has provided inputs and roadmaps for the development of large scale simulation strategies for greener technologies to meet future requirements on emissions, fuel consumption and noise and green materials.
Objectives
The main objectives of GRAIN have been to identify and assess the future development of large scale simulation methods and tools needed for greener technologies reaching the Vision 2020 environmental goals. GRAIN has prepared the R&T development and exploitation with new large scale simulation tools used on distributed parallel environments to deeper understand and minimize the effects of aircraft/engine design on climate and noise impact.
The participating institutions have focused on future collaborative applied research concerning modelling, experiments, simulation, control and optimization for greener aircraft and engines technologies including:
- emissions reduction,
- drag reduction,
- noise reduction and
- green materials
An emphasis on multidiscipline approaches (aero acoustics, aero thermal, aero Engine etc.) for environmentally friendly aircraft have been under evaluation, implying the assessment of high - performance computing facilities that are now available and upcoming in both Europe and China. New developments have been investigated concerning innovative methodologies on robustness and uncertainty for greener aircraft applications, taking benefit from high performance computing environments that can include graphic processors (GPUs) and high end supercomputing centres.
Scientific prospects
The activities in the GRAIN CSA have opened a wide range of scientific and technological prospects for future cooperation between European and Chinese organizations in the development and validation of new green technologies for aeronautical applications. Access to state of the art information on RTD activities in China and in Europe on greener technologies has opened many opportunities for the development of new and enhanced methods aiming to the emission reduction, noise reduction and green materials which will enable to reduce the environmental impact of aircrafts and air transport.
Technological aspects
The technological prospects have derived from the new modelling possibilities of experimental and computational advanced design of civil aircraft vehicles taking into consideration many multidisciplinary effects currently not strongly accounted for in practice and mainly related with environmental issues. The GRAIN Guidelines define the strategic lines and methodologies (both, numerical modelling and experiments) to be developed in the near future for the reduction of environmental impact of air transport. These guidelines bring flags and added values as a basis for setting up new RTD projects.
The general strategic objectives of the project have been three fold:
1) To identify areas of mutual RTD interest;
2) To develop concepts of collaboration in those Key Green Technological areas between the European and Chinese partners;
3) To prepare specific RTD activities which are mature for joint proposal for FP7-FP8.
Scientific and technical outputs and achieved results
As described in the DoW, the outputs of the project have been:
1) A state of the art document for each of the Key Green Technological area; the state of the art documents have been released in Month 6.
2) A web-based GRAIN Communication System for storage and dissemination of the collected data relevant to computational methods and experimental tests for multidisciplinary applications in aeronautics. The website http://www.cimne.com/grain is working and fully operative from the very beginning of the project. It includes a public area and a private one. Within the private one, a Library has been enabled to upload and share relevant information and knowledge within the consortium.
3) Definition of future joint RTD work on critical Key Green Technological areas. Several reports, describing the most promising activities and fields have been generated.
Above outputs have been disseminated and exploited both internally and externally by the project partners. External exploitation has addressed mainly two target groups: the aeronautics industry and the scientific community. The dissemination actions have included the planned kick-off workshop and full workshop in China, the Course and the final Forum in Europe as well as presentations of the GRAIN outputs at specialized industrial meetings (such as the Aeronautic Days organized by the EC).
1) China-Europe Workshop: held in China in October 2010.
2) Short Course: held by VKI in Brussels in July 2011.
3) Forum: held by CIMNE in Barcelona in November 2012
Project Context and Objectives:
Objectives
AEROCHINA1 and 2 have been networking projects co-funded by the 7th Framework Program (FP7) and by the China Aviation Industry Corporation (AVIC). Both projects have been coordinated by CIMNE and many of the GRAIN partners have participated in them. These collaborative projects gathered experts on the two Europe (13) and China (17) sides to foster cooperation and debate future trends in the field of integrated multi physics modelling, computer simulations and code validation, experimental testing and design methods for the solution of multi physics problems of interest to the aeronautic sector. AEROCHINA 1 and 2 identified areas of mutual RTD interest and skills, and experiences of Chinese partners in the relevant technological areas of multi physics analysis, experimentation and design through a series of dissemination events including short course, workshops and technical and strategic round tables. The outcomes of these two projects provided specific and mature RTD activities and teams for FP7 EU-China Coordinated calls.
The main objectives of GRAIN are to identify and assess the future development of large scale simulation methods and tools needed for greener technologies reaching the Vision 2020 environmental goals. GRAIN will prepare the R&T development and exploitation with new large scale simulation tools used on distributed parallel environments to deeper understand and minimize the effects of aircraft/engine design on climate and noise impact.
This objective can be met by supporting joint Europe-China networking actions for defining the necessary technologies to improve green aircraft performance. High-performance and innovative methodologies and algorithms must also be designed to take full benefit of high-performance computer infra structures existing or quite soon available in Europe and China.
These high-performance computing environments are nowadays compatible with remote distributed and parallel computations and are based on large multi-core systems, including graphic processors (GPU) systems. Some of them are closely linked to aeronautical institutes.
The participating institutions will focus on future collaborative applied research concerning modelling, experiments, simulation, control and optimization for greener aircraft and engines technologies including: emissions reduction, drag reduction, noise reduction and green materials with an emphasis on multidiscipline approaches (aero acoustics, aero thermal, aero Engine, ) for environmentally friendly aircraft. These collaborations will be dedicated to 3-D configurations (take off, cruise, approach and landing) and these configurations will imply the use of high - performance computing facilities that are now available and upcoming in both Europe and China. New developments will be investigated concerning innovative methodologies on robustness and uncertainty for greener aircraft applications, taking benefit from high performance computing environments that can include graphic processors (GPUs) and high end supercomputing centres.
Project Results:
1. Introduction
GRAIN - Greener Aeronautics International Networking - represents an EU-China Support Action that was co-funded by the 7th Research Framework Programme of the EU and the Ministry of Industry and Information Technologies MIIT of the People's Republic of China. It has been designed to provide inputs and roadmaps for the development of strategies for greener technologies in aviation to meet future requirements on emissions, fuel consumption, noise, green materials and large scale simulation.
The main objectives of GRAIN were to identify and assess the future technological developments needed for greener technologies to help reaching the environmental goals of Europe's Vision for Aviation 'Flightpath 2050'. GRAIN aims to prepare RTD activities and their exploitation to deeper understand and to minimize the effects on climate and of noise impact by aircraft/engine design. This objective can be achieved with the help of supporting joint Europe-China networking actions for defining the necessary technologies to improve green aircraft performance.
The activities of the GRAIN network have been defined and organized around the Key Green Technological (KGT) groups, which were composed by experts of the GRAIN partners from Europe and China. This report summarises the main outcome of each of the project's technical area, draws some final conclusions and finally proposes technology strategic guidelines for future development.
2. KGTs summary and main outcomes
2.1. KGT1- Emission reduction technologies - NOX and contrail emissions reduction
State-of-the-Art
The emissions from the kerosene burning gas turbine engine include a mixture of the nitric oxide and nitrogen dioxide collectively known as NOX. NOX emissions are significant for two completely separate reasons. The first is relevant to the problem of 'local air quality' around airports and arises because NOX is harmful when it is breathed by humans. The second is relevant to the problem of global warming and is related to the emissions in cruise. NOX affects the balance of two important greenhouse gases, namely methane and ozone.
The phenomenon of contrail formation has been studied for over 70 years. During the day, their principal effect is to reflect sunlight back into space, i.e. a cooling effect. However, at night the predominant effect is to warm the atmosphere. The global average net effect of contrails is believed to be a small contribution to global warming. The conditions under which contrails may form are reasonably well understood. First the aircraft must fly through air that is supersaturated with respect to water. Whilst this is a necessary condition, it is not sufficient since the aero-thermodynamic characteristics of the engine exhaust must also exceed certain thresholds. Notwithstanding this, the initiation process itself, i.e. the formation of the ice particles, is still not fully understood. If air is also supersaturated with respect to ice contrails can persist for longer time and then have a much greater impact on global warming than the precursor contrails. If this is correct, contrail induced cirrus may be one of aviations largest contributions to global warming.
Description of the research topics of mutual interest for both European and Chinese sides
Topic 1: Definition of strategies to reduce the impact of contrails in the global climate change
1) Conditions under which ice crystals form:
For ambient temperatures below a certain threshold (Schmidt-Appleton criterion) contrails form by condensation of water vapour onto suitable nucleation sites such as soot particles emitted by an engine as the result of mixing between exhaust and ambient air. The initially linear contrail can spread in high-supersaturated ambient conditions and evolve into contrail cirrus that may be indistinguishable from natural cirrus.
2) Contrail models:
Modelling the formation and evolution of contrails requires accurate methods like three-dimensional large-eddy simulations to capture the unsteady features of the aircraft wake, and robust microphysical models to represent the non-linear effects of ice microphysics.
3) Contrail-to-cirrus transition and implication on global climate change:
Contrail-to-cirrus transition is an important component of contrail modelling since cirrus cloud can spread to such an extent that it can be 'detected' by global models. In order to insure consistency between models, contrail-cirrus parameterizations should be developed to insure the information coming from detailed contrail simulations is transferred properly to global models in a way similar to that when developing subgrid-scale model for LES.
4) Environmental impact of contrail avoidance (trade-off between contrail effects and CO2 effects):
From an operational point of view persistent contrails could be avoided by flying into sub-saturated regions. Since this could lead to an increase of fuel consumption, a trade-off has to be found between contrail effects and CO2 effects.
5) Estimation of the global extent of aviation induced cirrus and its climate impact:
Rationale: The recently emerging meteorologically based evidence suggests that contrails and particularly contrail induced cirrus cloud may well be the largest single contribution that aviation makes to the process of global warming and, hence, climate change. Up to now, it has been assumed that CO2 emissions are aviations most important contribution to global warming with the largest amount of research being directed towards reducing aviation based CO2. However, if the real issue is aviations net contribution to global warming in the short term, a new and different strategy may be needed to reduce aviations impact. Consequently, it is necessary to gain a much better understanding of contrail formation and the potential for contrails to evolve into persistent high altitude cirrus cloud.
Topic 2: Definition of strategies to reduce the impact of NOX in the global climate change
Short description:
Current physics based models are yielding good results and allow the generation of 'data' for use in design and in the formulation of empirical models. It appears to be possible to formulate reasonably accurate 'correlation' models. However, more work needs to be done on the LES computation so that they can better inform the formulation of physics-based combustor models. On another front, we need to develop technologies to further reduce emissions in the LTO cycle in order to improve airport capacity.
Main objectives:
- To develop computer models of NOX emissions from kerosene burning gas turbine engines.
- To develop technologies to further reduce emissions in the LTO cycle in order to improve airport capacity.
List of activities:
1) Modelling the emissions and evolution of exhausts in the atmosphere using a chain of models;
2) Development of low emission combustors; and
3) Transversal action: HPC and interaction with KGT5.
2.2. KGT2 - Drag reduction technologies - CO2 emissions reduction
State-of-the-Art
The ACARE 2020 ambitious vision on CO2 emissions requires a global effort, and on many different fronts, to be achieved. A significant contribution can come from technologies for reducing aerodynamic drag. In this field many research efforts have been made and significant know-how has been accumulated in Europe and in China. Objective of this short note is to underline common trends and research paths that can be jointly pursued by Chinese and European partners.
For the sake of completeness, the trends that have emerged from the study of the state of the art are listed here:
a) Turbulent drag reduction;
b) Laminar flow technology;
c) Multi-object and Multi-disciplinary robust optimization;
d) Flow control; and
e) High fidelity CFD tools.
Description of the research topics of mutual interest for both European and Chinese sides
Topic 1: Integrated Drag Reduction Techniques for an Ultra high aspect ratio aircraft
Short description:
Research on 'Integrated Drag Reduction Techniques for an Ultra high aspect ratio aircraft', focused on HLFC wing design and turbulent flow control, combined with open rotor engine development, including configure aerodynamic optimum, laminar wing design, high-lift devices design, HLFC tech, riblets (or other turbulent drag reduction) design, high accuracy and high efficient CFD research and application, etc.
Main objective:
To research integrated drag reduction techniques on Ultra high aspect ratio aircraft, and also develop necessary numerical & experimental validation methods, aiming 2020 green aviation goal.
Outline of the approach and expected achievements:
Europe and China have a unique combination of technical expertise and industry requirement to develop, by following approaches:
- Attract technical experts to join this work. With great effort from project GRAIN, MARS and previous projects, China has fundamental team interested in this project.
- The wing layout parameter Optimum design, by developing efficient tools.
- Shock control by bump design, mainly by developing CFD design process.
- Research on riblets (multi-scale) or dimples design and simulation for turbulent drag reduction.
- HLFC wing and natural laminar v-tail to evaluate the drag reduction, by developing accurate CFD methodology.
- Introducing techniques developed in MARS on turbulent flow control.
- Limited wind tunnel tests to validate the drag reduction results and CFD design also produce data base for future use.
Then we can achieve the design methodology, develop better design process and tools, and get to know the integrated drag reduction effects. In the end we can form technique store for civil aviation further and greener development.
2) Topic 2: Turbulent drag reduction for civil transport aircraft fuselage
Short description:
The research work will focus on an integrated approach, simultaneously considering all the available and feasible technologies, to reduce the drag of fuselages or blended wing/body aircraft. The problem will be faced following a multidisciplinary approach that will allow studying it in all possible aspects and implications:
- New architectural and structural concepts and their implication on aerodynamic design.
- Passive and active devices for turbulent drag reduction.
- High fidelity computational tools and advanced MDO optimization methods for integrated aerodynamic/structural fuselage design.
Main objectives:
Develop an integrated MDO design technology aimed at the low turbulent drag fuselage design. Develop guidelines for turbulent drag reduction in fuselage and blended wing/body aircraft. Propose new concepts and technologies for turbulent drag reduction in fuselages.
Conclusions:
The choice of a common objective on which the joint research efforts may converge, among all the possible alternatives, is linked to the requirement that, in addition to being of common interest, the said field was not already been explored in depth from one of the two partners, so as to be of strategic interest to both. From this point of view, European partners, and primarily Airbus, consider that is possible to work fruitfully in the field of turbulent drag reduction. In particular, the reduction of the resistance of the fuselage might be of common strategic interest. This objective can be achieved by working on multiple fronts:
- introduction of new types of configuration for the aircraft;
- development of active and passive devices to control the flow; and
- project of micro and nano-mechanical devices for drag reduction and control of separate flows.
The Chinese partners, however, consider that there is also a strong strategic interest for the development of technologies for laminar flow, either natural or controlled or else hybrid. The European partners, while recognizing the validity of this statement, consider, however, that collaboration can develop in a more concrete and effective action on issues related to turbulent flows.
2.3. KGT3 - Noise emission reduction
State-of-the-Art:
According to noise emission regulation towards future aircraft noise, for instance Europe's Vision for Aviation 'Flightpath 2050' sets the objective of a noise reduction by 65%, relative to the capabilities of typical new aircraft in the year 2000. Such an ambitious target requires further development in the control strategy, numerical tool for mechanism understanding and prediction with accuracy and effectiveness, as well as experiment methods for validating such strategy and tools.
It has become common understanding that the engines and airframe are the main contributors to the noise radiated outward and received by those on the ground or in the cabin. Therefore, in order to reduce the aircraft noise, both two aspects need to be targeted. The airframe noise by tackling both landing gears and high lift devices, which are the two main contributors to airframe noise of an aircraft at approach as well as the engine noise addressed through its fan component, which accounts for a large fraction of the engine contribution to far-field noise, all these identified sources reveal their common property as 'flow induced'. Therefore any effective reduction strategy towards these noise issues will have close links with fluid dynamics and aero-acoustics.
After the retirement of the supersonic airliner Concorde, the current aircraft in service are all flying in the high subsonic range. However, there is a clear need from the stakeholders to have faster transportation in long distances (like between Europe and China) which necessitate completely new aircraft design. On the other hand, to answer the concerns regarding air transportation, the next generation of aviation should demonstrate significant progress in environment and low emission target. With the already highly optimized configurations, it is not possible to reach significant steps forward.
In order to be able to judge new possible configurations, efficient technologies have to be developed to aid the design phase. On the other hand, the deep understanding of the physics behind noise generation can help to distinguish between able configurations and further refine the selected versions.
Over the past decade, a significant progress has been made, sustained by a number of European networks and projects, to reach a better understanding of the physical mechanisms through which noise is produced by high-lift devices, the under-carriage and the engine fan. Direct Computational Aero-acoustics (CAA) and hybrid approaches based on Computational Fluid Dynamics (CFD) and various forms of the acoustic analogy have largely contributed to a better modelling of the sources giving rise to acoustic waves. As a result, a fair accuracy is obtained nowadays in the prediction of the acoustic far-field noise emitted by some airframe and engine components, compared with experimental data gathered by means of sophisticated microphone arrays and processing techniques.
The European partners are collaborating in several European FP7 and Marie Currie projects related to aero-acoustics as VALIANT, IDIHOM, ANADE, IDEALVENT, ORINOCO, TEENI, DREAM, FLOCON. A workshop was organized by VKI in the frame of the famous Lecture Series, 'Advanced Methods and Tools for Reducing Environmental Impacts in Aeronautics Design for Aircraft and Aero-engines'. Besides several papers were presented by the partners in international conferences such as the yearly AIAA Aero-acoustic Conference, Inter-Noise, ICSV and the two-yearly organized ISMA Conference.
Topic: Noise control methodology research, numerical tooling and experimental validation development
Main objective:
To develop noise control methodologies and necessary numerical tool and experimental validation methods, aiming future noise criteria for aircraft noise. For a number of reasons further detailed in the following sections, these technologies require further developments to tackle airframe and fan applications and deliver their benefits:
- The physics of the mechanisms responsible for the flow alteration is still insufficiently understood. This lack of understanding prevents assessing quantitatively the scalability, costs and benefits of the control approaches, once implemented on the real aircraft.
- As a result, the physical modelling of the control technology in a CFD context is still immature, while such numerical simulations are necessary to carry on effective parametric studies and optimize the control within acceptable run-times and costs.
- Further development in conceptual design or methodology advancement will face requirement and actual desire on validated technology from the industry side. Therefore numerical tools, experimental techniques and new methodologies must be validated with each other and more over, with known knowledge and techniques.
A rational choice of the most suitable/efficient approach is significantly complicated in absence of any quantitative experimental or numerical assessment of the different control approaches. There is a crucial need for new reference experimental data and systematic comparative studies of different control strategies as applied to generic configurations reflecting physics of noise-generation by the noisiest elements of civil aircraft. That systematic work will:
- Contribute to document the costs and benefits of different control approaches, and
- Form a trusty experimental database for elaborating physically consistent numerical models.
A fundamental point of interest is the development of simplified, yet reliable, representations of the effects of control devices in a CFD context. Because of the intrinsic cost of the unsteady CFD simulations that are involved in CAA and hybrid approaches, having a simplified, macroscopic description of the control device is required in order to simulate the steady and transient behaviour of the controlled flow in an affordable way. This is a pre-requisite to the optimization and eventually implementation of the control techniques in the application field. Sound absorbing porous materials for use in aerospace applications must meet stringent yet well accepted requirements concerning, especially, weight and also fire resistance. For such applications, certain types of porous materials, with their inherent multi-functionality, can be used as a part of systems engineered to reduce unwanted noise at a low overall weight.
Although the works devoted to the impedance of materials including flow effects have been conducted since the 1970s, the mechanisms underlying the acoustic response of the medium in the presence of flow have not yet been fully examined. Furthermore, recent manufacturing techniques permit producing new layouts and structures, giving increased and extended absorption characteristics with zero weight penalty and minimal manufacturing complexity. New porous materials can also be arranged in locations that were not considered before.
Talking about the topic of environmental friendly, recent development of composite material from both natural fiber and polymer has reveal its potential in better acoustic property (e.g. absorption coefficient in broad frequency band because of its hollow nature) and after life disposal. Combination of material science, engineering and manufacture process will be the way to achieve success and more environmental friendly aircraft. An important goal is therefore set to be the characterization and modelling of innovative porous materials (including natural material) and layouts (e.g. engine nacelle liner and cabin isolation panel, etc) for the suppress noise source level and propagation.
As stated by the ACARE Group, the objectives reached through a strategic collaboration with China, Russia and India are meant to benefit to European citizens, the European aerospace industry and to promote efficient international arrangements.
Generally speaking, the capacity of the Chinese partners to mobilize an important contingent of skilled researchers within the available budget envelope offers a formidable leveraging effect to multiply the benefits of the research carried out in Europe. In the other direction, a collaboration could offer opportunities to the Chinese partners to have a privileged access to the European research practices, which will facilitate further cooperation in the future.
This cooperation will also be promoting an enhanced EU market attraction to one of the fastest growing economies in the world. In the current competitive context between the European aircraft manufacturer Airbus and the American manufacturer Boeing, fostering synergies between the European and Chinese research poles may be a key to securing a leading position in the race.
Outline of the approach and expected achievements: Europe and China have a unique combination of technical expertise and industry requirement to develop:
- Innovative noise control methodology via flow control (e.g. plasma actuator, turbulent mesh, etc) for airframe noise reduction;
- Further development on engine nacelle liner to archive better suppressing property in broader frequency band via new conceptual development and application of natural composite;
- Modelling of flow induced noise with high accuracy and effectiveness yet lower computational cost, via more advanced scheme, turbulent models and HPC support; and
- Experimental technique to validate conceptual design and numerical tool as mentioned above, also produce data base for future use.
Partners:
The work will be divided into numbers of packages concerning the main content and goal, technique domain and recent readiness, and interest by joint participants. With great effort from project GRAIN and previous projects, China has numbers of institutes with large scale acoustic and flow facilities that can support conceptual development and experimental validation technique development. This ensures the frontend and finalization of research process if the philosophy was set as 'conceptual design-numerical modelling-experimental validation'.
China also has solid team lead by mainly universities, with capability and expertise in development of physics model, numerical tool and optimization methods. This ensures the numerical modelling process in entire philosophy, as powerful jet effective kneel tool.
Industry from China, with their rapid business expansion and eager requirement to future greener technology will provide valuable validation opportunities on full scale, pushing technologies developed to higher readiness level.
2.4. KGT4 - Environmentally friendly materials and structures - green materials
State-of-the-art:
In the last 2 years since GRAIN started, significant progress has been achieved on the green materials, particularly the green composite materials in a cooperative way between the European and Chinese partners. Firstly, a Chinese national team has been established led by BIAM with the key players of NIMTE and Tongji University. The team meets 3-4 times each year to discuss and exchange information of the latest development on green materials and successfully co-organized three international workshops on bio-sourced materials for aerospace and ground transportation. They presented in the same time 8-10 papers at different international conferences on advanced material development. Today, the team is the leading research body with reputation in China for its R&D of green materials and the technology.
Secondly, the team with its consortium is successfully developing bio-sourced epoxy resins and bio-degradable polylactide plastics. The materials have been evaluated and demonstrate competitive advantages against the traditional one even they are now still at the trial product phase. Besides, they are also developing natural fiber composites based on the plant fibers rich in China. As tested and demonstrated, the composites exhibit promising properties which could meet the requirements for aircraft interior structures.
European partners have proved a complete expertise on innovative technologies such as smart materials, structural design and simulation in composite materials, out-of-autoclave processing technologies, process simulation and optimization, mechanical and acoustic characterization, ageing conditions effects, surface treatments on fibers, or life cycle assessment.
The deliverable 5.2 'Report on Emerging RTD Areas of KGT4' of GRAIN project shows a complete description of the technological contributions and related publications and research projects of both Chinese and European partners.
Topic: Advanced bio-sourced composite materials for aeronautical applications
Main objective:
To develop bio-sourced polymeric resins, reinforcing fibers and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components.
Short description of the benefits to both China and Europe:
Europe and China have a unique combination of technical expertise to develop bio-sourced composite materials, aeronautical structures and related manufacturing technologies beneficial to both aviation industries. There is also a synergy between the materials development in China and the aeronautical application development in Europe that can work together to provide a complete material-based solution with minimized risk in demonstration and future application.
European and Chinese partners see advantages on carrying this project through cooperation. Chinese partners stated knowledge and expertise on the greener materials technologies, including bio-sourced fibres, resins and core-material technologies for sandwich structures, material protection technologies (bio-based fire retardants, surface treatment and resin blending technologies...) and material characterization. European partners have high knowledge and expertise on development of aircraft interiors and structures, including design, simulation, prototype manufacturing, demonstration test and comfort engineering.
Therefore, an important sharing of knowledge and expertise will be produced between both European and Chinese partners. Industrial partners showed a high interest on this project as an important step to achieve future greener composite material aircraft interiors and structures. The targeted structures are tentatively considered to be large secondary structural components and interior components.
2.5. KGT5 - High performance computing for aeronautical applications - large scale high performance methodologies with advanced it tools
State-of-the-art:
In the area of High Performance Computing (HPC) a number of critical topics must be addressed to take full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications.
Among these topics are: programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi-core CPU-GPU), fault-tolerance, cloud computing and very large datasets management.
None of these have found satisfactory solutions so far, and they are the focus of many research projects around the world. The proposal stresses the importance of investing in these areas for the mutual benefit of application development and systems performance in aerospace engineering.
The following items are the outcome of KGT5 group proposing research areas of mutual interest, focusing on the HPC items and their application to the following subjects: Airframe flight physics including: drag reduction, noise reduction, HPC innovative architecture, numerical simulation.
Topic: Large scale high performance computing
The objectives are to define common collaboration topics leveraging the use of HPC environments in order to:
- gain competitive advantages;
- deploy simulations of increasingly complex phenomena with greater physics fidelity;
- foster industrial competitiveness through advanced HPC simulation-based engineering science tools
- promote new insights gained from advanced simulations that permit increasingly realistic dynamics for deeper understanding of flight physics in real and virtual environments; and
- emphasize topics suitable for collaborative projects funded by the EC in the aeronautics field.
Target applications - Application areas of critical importance are:
- Full flight envelope characterization;
- Understanding and predicting aerodynamic flow generated noise; and
- Accurately predict and quantify uncertainty in large-scale full-fledged virtual experiments.
The areas mentioned above need contributions on the following subjects:
- HPC frameworks co-design, including hardware, systems and applications characteristics;
- Rationale: uncertainty quantification, multi-scale from the start designs, fully predictive & accurate simulations;
- Fault-tolerant algorithms, quick runtime plausibility tests, uncertainty quantification, error aware, multi-core & many-core aware algorithms;
- Virtual labs & Numerical wind tunnels;
- Verification & validation that are even more crucial than in the past;
- Deployment of high-fidelity computations as calibration tools for reduced order simulations codes;
- Path from RANS to LES simulations plus robust optimization strategies & increased predictive capability, that are allowed by increased computing power;
- Robust design, e.g. aerodynamic noise reduction, combustion in aerospace turbines; and
- Fitting new problems scale with massively parallel computers.
These topics need the following HPC challenges to be addressed:
- System resilience;
- System (hardware, systems, applications) co-design;
- Mathematical modelling;
- Numerical algorithms;
- Algorithmic challenges: programming models + extremely robust I/O and storage systems;
- Robust, scalable effective implementations of MPI;
- Combination of existing and future parallel languages, needed for incremental progress;
- Multi-stage fault-tolerance: system, hardware, application codes;
- Multi-core/many-core programming environments + intra-chip multithreaded parallelism;
- Hybrid CPU-GPU programming environments; and
- Cloud computing environments: opportunities and drawbacks.
The KGT5 GRAIN partners deem necessary to foster collaborations on the abovementioned topics by continuous efforts that involve the interested teams from both China and Europe, with particular efforts to solve the challenges related to HPC applications deployment on the petascale and future exascale super-computers.
The outcome will be technical roadmaps and recommendations on the items selected and supported by experiments run by the teams involved. All of these items are clearly technology steps to be worked out in suitable collaborative projects funded by the EC.
3) Synthesis
The final report has been prepared with contributions of European and Chinese GRAIN partners. GRAIN is an EU-China Coordination and Support Action developed from October 2010 to December 2012 in Europe and China.
This bilateral EU-China project has brought together experts from Europe (16 industrial and scientific experts) and China (13 industrial and scientific) on 'Greening of the Aircraft' areas activities according to objectives of the ACARE Vision 2020 and Flight path 2050 vision for the Aircraft reports.
The European-Chinese consortium members have been split into five (5) Key Green Technologies (KGTs) areas according to their expertise: Emission reduction of NOx ( KGT1), CO2 reduction (KGT2), Noise reduction ( KGT3), Friendly environmental Materials ( KGT4) and HPC environments for large scale simulations (KGT6).
Two Open Workshops/Forums on the above topics took place in Beijing (2010) and Barcelona (2012) with presentation of KGTs activities and invited lectures of Non GRAIN experts from Europe and China. A Short Course organized by the Von Karman Institute, Brussels in 2011) provided deeper knowledge: State of the Art on 'Advanced methods and tools for reducing the environmental impact (NOx, CO2, Noise, Materials)'
The main outcomes of GRAIN in the different areas are the following:
1) KGT1: NOx is relevant to the problem of 'local air quality' and harmful and affects methane and ozone; formation of ice particles is not yet fully understood and has a greater impact on global warming than precursor contrails. Topics of mutual interest were: conditions under which ice crystals form and contrail models. Activities were focused on future strategies how to reduce the impact of contrails in the global climate change including the modelling emissions, the evolution of exhausts in the atmosphere using a chain of models and the development of low emission combustors.
2) KGT2: CO2 emissions reduction techniques were collected and prospected on:
a. integrated drag reduction techniques for an Ultra high aspect ratio aircraft (Laminar control techniques relatively important for future transport aircraft, as well as turbulent drag reduction by controlling the Reynold stresses ( MARS EU-China project) and reliability on transition.
b. Europe and China teams have shown a unique and complementary combination of technical expertise and industry requirements.
c. turbulent drag reduction for civil transport aircraft fuselage to reduce the drag of fuselages or blended wing/body aircraft (BWB) via passive and active devices and high fidelity computational tools and advanced MDO optimization methods. Integrated MDO design technology aimed at the low turbulent drag fuselage design.
New concepts and technologies for turbulent drag reduction in fuselages have been prospected with test cases of industrial interest for both Chinese and European partners. European industrial partners consider that is possible to work fruitfully in the field of turbulent drag reduction and Chinese partners, however, consider that there is also a strong strategic interest for the development of technologies for laminar flow.
3) KGT3: Noise Emission Reduction
Engines and airframe are the main contributors to the noise radiated outward and received by those on the ground or in the cabin: the airframe noise by tackling both landing gears and high lift devices and the engine noise addressed through its fan component. Effective noise reduction strategies have close links with fluid dynamics and aero-acoustics. A significant progress has been made, sustained by a number of European networks and projects, to reach a better understanding of the physical mechanisms through which noise is produced by high-lift devices, the under-carriage and the engine fan. CFD and various forms of the acoustic analogy have largely contributed to a better modelling of the sources giving rise to acoustic waves.
European partners are collaborating in several European FP7 and Marie Currie projects related to aero-acoustics as VALIANT, IDIHOM, ANADE, IDEALVENT, ORINOCO, TEENI, DREAM, FLOCON
Topics investigated during the development of GRAIN:
- developing noise control methodologies and necessary numerical tools and experimental validation methods, aiming future noise criteria for aircraft noise.
- passive or active flow control hence noise generated e.g. plasma actuation, turbulence screens engine noise control through advanced liner concept and using more acoustic effective yet environment friendly material to archive better cabin acoustics have shown their potential
The physical modelling of the control technology in a CFD context is still immature. There is a crucial need for new reference experimental data and systematic comparative studies of different control strategies as applied to generic configurations reflecting physics of noise-generation. Europe and China have a unique combination of technical expertise and industry requirement to develop innovative noise control methodology via flow control (e.g. plasma actuator, turbulent mesh, etc) for airframe noise reduction; modelling of flow induced noise with high accuracy and effectiveness yet lower computational cost, via more advanced scheme, turbulent models and HPC support, experimental techniques to validate conceptual design and numerical tools, produce data base for future use.
4) KGT4 - Environmentally Friendly Materials and Structures
Significant progress has been achieved on the green materials, particularly the green composite materials in a cooperative way between the European and Chinese partners (BIAM, NIMTE and Tongji University, 8-10 papers presented at different international conferences on advanced material development). KGT4 partners have shown a complete expertise on innovative technologies (smart materials, structural design and simulation in composite materials, out-of-autoclave processing technologies, process simulation and optimization, mechanical and acoustic characterization, ageing conditions effects, surface treatments on fibers, or life cycle assessment (LCA) .
Topics investigated: Advanced bio-sourced composite materials for aeronautical applications including the development of bio-sourced polymeric resins, reinforcing fibers and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components. Bio-sourced materials will meet or partially exceed the mechanical properties and reliabilities available from standard petroleum-based materials.
Preliminary research and development on natural fibre composites and bio-based polymers have shown that the specific mechanical properties of the bio-sourced materials can partially compete with the petroleum-based resins. A synergy between the materials development in China and the aeronautical application development in Europe can work together to provide a complete material-based solution with minimized risk in demonstration and future application. Industrial partners showed a high interest on this project as an important step to achieve future greener composite material aircraft interiors and structures.
Among future activities identified by KGT4 members : Natural fiber composite technologies, Advanced core technologies, Bio-based resins for structural application, Bio-degradable resins for structural applications, Ageing behaviour improvement technologies, Development of the novel hybrid fire retardants, Development of aircraft structures using green composites, Development of greener aircraft interiors, Greener manufacturing, Life Cycle Assessment (LCA)
5) KGT5 - High Performance Computing for Aeronautical Applications
This group investigated the full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications including programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi-core CPU-GPU), fault-tolerance, cloud computing and very large datasets management. Multidiscipline applications were focused on airframe flight physics including: drag reduction, noise reduction, HPC innovative architecture, numerical simulation.
Common collaboration topics leveraging the use of HPC environments:
a) deploying simulations of increasingly complex phenomena with greater physics fidelity
b) promote new insights gained from advanced simulations that permit increasingly realistic dynamics for deeper understanding of flight physics in real and virtual environments
The identified application areas of critical importance are:
a) full flight envelope characterization;
b) the understanding and predicting aerodynamic flow generated noise,
c) Accurately predict and quantify uncertainty in large-scale full-fledged virtual experiments
d) Virtual labs & Numerical wind tunnels
e) Deployment of high-fidelity computations as calibration tools for reduced order simulations codes
f) Path from RANS to LES simulations plus robust optimization strategies & increased predictive capability, that are allowed by increased computing power,
g) Robust design, e.g. aerodynamic noise reduction, combustion in aerospace turbines
Among the HPC challenges identified:
a) programming models + extremely robust I/O and storage systems
b) robust, scalable effective implementations of MPI
c) multi-core/many-core programming environments + intra-chip multithreaded parallelism
d) hybrid CPU-GPU programming environments
e) cloud computing environments
Particular efforts are needed to solve the challenges related to HPC applications implemented on the petascale and future exascale super-computers.-
4) Conclusions and further actions
The highly ambitious vision 'Flightpath 2050' demands a global and multidisciplinary effort for achieving the identified targets. Significant contributions for reaching these targets can be obtained by developing the corresponding greening technologies. In this context research efforts have been made until now in Europe and in China and significant know-how has been accumulated. The main objective is to identity the future research areas for greening technologies that are of mutual interest of aviation stakeholders from China and Europe and can be jointly pursued in the future.
Major ingredients of the future research areas (emissions, CO2, Noise, Friendly Environmental materials and HPC environments for large-scale simulations) for greener technologies that are of mutual interest of aviation stakeholders from China and Europe have been identified.
Chinese -European teams working on the above areas have integrated and complemented expertises during the development of GRAIN, either with e- sessions or meetings in Europe open workshops. Motivated by excellent mutual scientific and friendly human understanding these EU-China teams will continue to deepen collaboratively their knowledge in future research EU-China projects.
Strategic Guidelines for Future Technology Development
Based on the detailed stat-of the-art studies developed by each of the Key Green Technology group the following main four (4) technology streams are identified for future actions:
1) Airframe configuration oriented technologies;
2) Environment and engine technologies;
3) Material and structure technologies; and
4) Numerical simulation and wind tunnel testing enabling technologies.
Airframe configuration oriented technologies
Several technology actions are considered here oriented to reduce airframe drag (induced and viscous) and weight. These are:
1) Innovative configurations for high aspect ratio designs;
2) Turbulent drag reduction technologies; and
3) Distributed propulsion and related boundary layer ingestion technologies.
Environment and engine oriented technologies
Several technology actions can be considered here for more efficient low noise and NOx engine together with the necessary activities for ice crystal, contrails and other particles modelling. These are:
1) High/ultra-high by pass ratio engine technologies
- Engine architecture, materials for higher temperature combustor, development of low emission combustors
- Develop noise control methodologies and necessary numerical tool and experiments for validation methods, for engine noise.
2) Environmental aspects
- Understand the fundamental of contrail physics: science of initial formation of the contrail, the evolution of the linear contrail and the conditions in which a linear contrail evolves into a cirrus cloud
- Develop models that can be used to assess the impact of the global aircraft fleet on global warming.
- Develop new strategies for minimizing aviations total climate impact
- Modelling the emissions and evolution of exhausts in the atmosphere using a chain of models
Materials and structure technologies
The trend here is to develop bio-sourced polymeric resins, reinforcing fibres and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components.
Numerical simulation and wind tunnel testing technologies
- Advancement of flow diagnostic tools (PSP, TSP, 3-D TomoPIV etc) to assist code development and validation.
- For numerical simulation a number of critical topics must be addressed to take full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications. Among these topics are: programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi- core CPU-GPU), and very large datasets management.
- Physical modelling for separated unsteady flows.
Potential Impact:
Scientific prospects
The activities in the GRAIN CSA open a wide range of scientific and technological prospects for future cooperation between European and Chinese organizations in the development and validation of new green technologies for aeronautical applications. Access to state of the art information on RTD activities in China and in Europe on greener technologies opens many opportunities for the development of new and enhanced methods aiming to the emission reduction, noise reduction and green materials which will enable to reduce the environmental impact of aircrafts and air transport.
Technological aspects
The technological prospects will derive from the new modelling possibilities of experimental and computational advanced design of civil aircraft vehicles taking into consideration many multidisciplinary effects currently not strongly accounted for in practice and mainly related with environmental issues. The GRAIN Guidelines will define the strategic lines and methodologies (both, numerical modelling and experiments) to be developed in the near future for the reduction of environmental impact of air transport. These guidelines will bring flags and added values as a basis for setting up new RTD projects.
Contribution to EU policies
The GRAIN proposal will be co-funded on a symmetric basis by European Commission for European partners and by Chinese Authorities (MIIT) for Chinese partners as it is shown by an e-mail from AVIC, attached in Annex.
This project aims to enhance the open cooperation between Europe and China in the field of aeronautic research and engineering. Indeed this goal was achieved of the conclusions of the EU-China workshop in Aeronautics held in Beijing on April 15 2005, also confirmed on the latter AEROCHINA 2 project final meeting in Brussels in September 2009.
AEROCHINA 1 & 2 CSA projects have been a very good example of leverage successful networking projects that were coordinated by CIMNE with the participation of many of the GRAIN partners. The contribution of both AEROCHINA projects to EU policies has been demonstrated trough the production of different collaborative development topics that has been used for the definition of a FP7 Coordinated Call in 2010.
The specific scope of the GRAIN proposal also fits within several aspects of the European Union policies. Improvement of the design, analysis and validation tools will help to build safer and more competitive aircrafts with improved environmental features (fewer emissions. Indeed producing safer and cleaner airplanes is one of the targets to guarantee better protection of passengers. The enhancement of greener aircraft design, manufacturing and maintenance is one of the key aspects for a sustainable European aerospace industry meeting the challenges and demands of the air-transport sector for the next decades.
The objectives of the GRAIN proposal fit with the guidelines and recommendations proposed in the vision for 2020 EC report on European Aeronautics. The response to issues of public interest is a key element of the 2020 Vision Agenda including multidisciplinary problems such as noise reduction, emission reduction and safer air transport and affordability.
In summary, the joint activities of the GRAIN project will be of value for helping to achieve the goals of the research agenda in the European aeronautics sector in the next two decades. As clearly specified in the 2020 Vision report only 'an integrated research approach can provide the basis for satisfying societys need and ensuring European leadership in the global aerospace market by 2020'. Helping to build this integrated research scenario through a better cooperation between European and Chinese organizations in the solution of environmental issues in aeronautics is one of the main goals of the GRAIN proposal.
The successful development of the GRAIN project will open new opportunities for creating employment in a number of strategic lines. Thus, by having access to state of the art computational methods and software for a better design and production of aeronautic vehicles in a multidisciplinary environment, the need for skilled engineers will increase the demands for jobs. Similarly, new training and education programs will have to be implemented for developing the skills of practising and newly graduated aerospace engineers into the possibilities of the new methods for multidisciplinary design. This will also contribute to the preservation and creation of employment in Europe.
The interaction between partners from different organizations in Europe and China (aeronautics/aerospace industries, RTD centres, universities and international associations) will lead to an exchange of technical and policy ideas and personnel which will help towards making more attractive the work in these fields.
The GRAIN data will also find application in markets different from the aeronautic sectors that also need the computational multi physics transport technologies (i.e. turbo machinery, civil construction, naval architecture, automotive industrial forming processes, etc.). Transfer of the GRAIN greener multi-physics technology to these sectors through adequate disseminating actions (i.e. lecture series, road maps, workshops, conferences, publications, etc.) will help to create new attractive cooperative RTD scenarios and business opportunities for cooperation between different sectors and this will also contribute to the creation of new jobs.
Environment
The 2020 Vision aims to make European Aeronautics a global leader in the world market with safer, less noising and less polluting aircrafts. The GRAIN CSA activities and outputs will contribute towards achieving these goals by preserving the environment in a number of ways. First, one of the main goals is the improvement on the methods which enables the emission reduction. In addition, a better aerodynamic and acoustic design of aircrafts, plus the use of cutting-edge materials which will reduce the total weight of the aircraft will also be beneficial for reducing the emission of external and internal noise. The development of emission and noise reduction techniques is one of the goals of the 2020 vision report.
Likewise, a better understanding of flow turbulence and turbulence/chemistry interactions will contribute to a reduction of fuel consumption and pollution emissions. In addition, a better design of aircraft and structures (obtained by accounting for all the couplings and interactions of the participating physical phenomena) will ensure a longer durability of components and integrated aircraft vehicles. Finally the modelling of uncertainties in analysis and design software will contribute to reduce significantly margins which warranty the maintenance of performances and stability within real operations of aircraft. This will invariably contribute to extending the life cycle, thus, reducing the environmental impact of maintenance and replacement.
Quality of life, health and safety of the citizens
The objectives of the GRAIN proposal respond to a number of societal needs. Indeed, the design of safer, cleaner and quieter aircrafts has a direct impact on the quality of life and safety of citizens.
The GRAIN multidisciplinary data will be an essential contribution for developing new methods for the understanding of flow/turbulence and chemistry interactions, the better design of aircraft structures reducing noise emission, fuel consumption, fuel emissions and for extending the life of aircraft vehicles. All these aspects will have a very positive impact on the quality of life and health of citizens.
Indeed the design and production of aircraft structures with better endurance limits will contribute to reduce the technological risks involved in aircraft construction and operation. This will also have a very positive effect in the overall safety of aircrafts and, hence, on the safety of citizens.
GRAIN will confirm the hopes of proposers from new identified collaborative methods and tools for the design new civil and business aircraft in terms of performances, environmental problems and safety to issue a roadmap leading to a significant improvement (30% or more) over the existing range.
Project website:
http://www.cimne.com/grain
Technical Contact in CIMNE
Prof. Jacques Periaux, jperiaux@gmail.com
Prof. Gabriel Bugeda, bugeda@cimne.upc.edu
Greener Aeronautics International Network (GRAIN) is a 'Cooperation and Support Action' project which comes from the effort done in AEROCHINA and AEROCHINA 2 projects. AEROCHINA1&2 have been networking projects co-funded by FP7 and AVIC (China) and coordinated by CIMNE.
Background
The continuous increase of air passenger transport generates an increasing use of hydrocarbon fuel with excessive emission of CO2 and NOX (greenhouse gases and pollutants and noise). It is well known that commercial aircraft operations impact the atmosphere by the emissions of greenhouse gases and greenhouse gas precursors and also through the formation of contrails and cirrus clouds. The EC has published in 2000 the future of aeronautics in the ACARE Vision 2020 containing the ambitious goals on the environmental impact with 80% reduction in NOX emissions, 50% reduction in CO2 emissions per passenger kilometre, and the reduction of the noise in by 20dB (50% reduction on the perceived noise). To achieve the ACARE Vision 2020 goals green aeronautics technologies will play a more and more dominant role. GRAIN Supported Action, based on the same collaborative and win-win spirit introduced in former EU-China AEROCHINA 1 & 2 projects has provided inputs and roadmaps for the development of large scale simulation strategies for greener technologies to meet future requirements on emissions, fuel consumption and noise and green materials.
Objectives
The main objectives of GRAIN have been to identify and assess the future development of large scale simulation methods and tools needed for greener technologies reaching the Vision 2020 environmental goals. GRAIN has prepared the R&T development and exploitation with new large scale simulation tools used on distributed parallel environments to deeper understand and minimize the effects of aircraft/engine design on climate and noise impact.
The participating institutions have focused on future collaborative applied research concerning modelling, experiments, simulation, control and optimization for greener aircraft and engines technologies including:
- emissions reduction,
- drag reduction,
- noise reduction and
- green materials
An emphasis on multidiscipline approaches (aero acoustics, aero thermal, aero Engine etc.) for environmentally friendly aircraft have been under evaluation, implying the assessment of high - performance computing facilities that are now available and upcoming in both Europe and China. New developments have been investigated concerning innovative methodologies on robustness and uncertainty for greener aircraft applications, taking benefit from high performance computing environments that can include graphic processors (GPUs) and high end supercomputing centres.
Scientific prospects
The activities in the GRAIN CSA have opened a wide range of scientific and technological prospects for future cooperation between European and Chinese organizations in the development and validation of new green technologies for aeronautical applications. Access to state of the art information on RTD activities in China and in Europe on greener technologies has opened many opportunities for the development of new and enhanced methods aiming to the emission reduction, noise reduction and green materials which will enable to reduce the environmental impact of aircrafts and air transport.
Technological aspects
The technological prospects have derived from the new modelling possibilities of experimental and computational advanced design of civil aircraft vehicles taking into consideration many multidisciplinary effects currently not strongly accounted for in practice and mainly related with environmental issues. The GRAIN Guidelines define the strategic lines and methodologies (both, numerical modelling and experiments) to be developed in the near future for the reduction of environmental impact of air transport. These guidelines bring flags and added values as a basis for setting up new RTD projects.
The general strategic objectives of the project have been three fold:
1) To identify areas of mutual RTD interest;
2) To develop concepts of collaboration in those Key Green Technological areas between the European and Chinese partners;
3) To prepare specific RTD activities which are mature for joint proposal for FP7-FP8.
Scientific and technical outputs and achieved results
As described in the DoW, the outputs of the project have been:
1) A state of the art document for each of the Key Green Technological area; the state of the art documents have been released in Month 6.
2) A web-based GRAIN Communication System for storage and dissemination of the collected data relevant to computational methods and experimental tests for multidisciplinary applications in aeronautics. The website http://www.cimne.com/grain is working and fully operative from the very beginning of the project. It includes a public area and a private one. Within the private one, a Library has been enabled to upload and share relevant information and knowledge within the consortium.
3) Definition of future joint RTD work on critical Key Green Technological areas. Several reports, describing the most promising activities and fields have been generated.
Above outputs have been disseminated and exploited both internally and externally by the project partners. External exploitation has addressed mainly two target groups: the aeronautics industry and the scientific community. The dissemination actions have included the planned kick-off workshop and full workshop in China, the Course and the final Forum in Europe as well as presentations of the GRAIN outputs at specialized industrial meetings (such as the Aeronautic Days organized by the EC).
1) China-Europe Workshop: held in China in October 2010.
2) Short Course: held by VKI in Brussels in July 2011.
3) Forum: held by CIMNE in Barcelona in November 2012
Project Context and Objectives:
Objectives
AEROCHINA1 and 2 have been networking projects co-funded by the 7th Framework Program (FP7) and by the China Aviation Industry Corporation (AVIC). Both projects have been coordinated by CIMNE and many of the GRAIN partners have participated in them. These collaborative projects gathered experts on the two Europe (13) and China (17) sides to foster cooperation and debate future trends in the field of integrated multi physics modelling, computer simulations and code validation, experimental testing and design methods for the solution of multi physics problems of interest to the aeronautic sector. AEROCHINA 1 and 2 identified areas of mutual RTD interest and skills, and experiences of Chinese partners in the relevant technological areas of multi physics analysis, experimentation and design through a series of dissemination events including short course, workshops and technical and strategic round tables. The outcomes of these two projects provided specific and mature RTD activities and teams for FP7 EU-China Coordinated calls.
The main objectives of GRAIN are to identify and assess the future development of large scale simulation methods and tools needed for greener technologies reaching the Vision 2020 environmental goals. GRAIN will prepare the R&T development and exploitation with new large scale simulation tools used on distributed parallel environments to deeper understand and minimize the effects of aircraft/engine design on climate and noise impact.
This objective can be met by supporting joint Europe-China networking actions for defining the necessary technologies to improve green aircraft performance. High-performance and innovative methodologies and algorithms must also be designed to take full benefit of high-performance computer infra structures existing or quite soon available in Europe and China.
These high-performance computing environments are nowadays compatible with remote distributed and parallel computations and are based on large multi-core systems, including graphic processors (GPU) systems. Some of them are closely linked to aeronautical institutes.
The participating institutions will focus on future collaborative applied research concerning modelling, experiments, simulation, control and optimization for greener aircraft and engines technologies including: emissions reduction, drag reduction, noise reduction and green materials with an emphasis on multidiscipline approaches (aero acoustics, aero thermal, aero Engine, ) for environmentally friendly aircraft. These collaborations will be dedicated to 3-D configurations (take off, cruise, approach and landing) and these configurations will imply the use of high - performance computing facilities that are now available and upcoming in both Europe and China. New developments will be investigated concerning innovative methodologies on robustness and uncertainty for greener aircraft applications, taking benefit from high performance computing environments that can include graphic processors (GPUs) and high end supercomputing centres.
Project Results:
1. Introduction
GRAIN - Greener Aeronautics International Networking - represents an EU-China Support Action that was co-funded by the 7th Research Framework Programme of the EU and the Ministry of Industry and Information Technologies MIIT of the People's Republic of China. It has been designed to provide inputs and roadmaps for the development of strategies for greener technologies in aviation to meet future requirements on emissions, fuel consumption, noise, green materials and large scale simulation.
The main objectives of GRAIN were to identify and assess the future technological developments needed for greener technologies to help reaching the environmental goals of Europe's Vision for Aviation 'Flightpath 2050'. GRAIN aims to prepare RTD activities and their exploitation to deeper understand and to minimize the effects on climate and of noise impact by aircraft/engine design. This objective can be achieved with the help of supporting joint Europe-China networking actions for defining the necessary technologies to improve green aircraft performance.
The activities of the GRAIN network have been defined and organized around the Key Green Technological (KGT) groups, which were composed by experts of the GRAIN partners from Europe and China. This report summarises the main outcome of each of the project's technical area, draws some final conclusions and finally proposes technology strategic guidelines for future development.
2. KGTs summary and main outcomes
2.1. KGT1- Emission reduction technologies - NOX and contrail emissions reduction
State-of-the-Art
The emissions from the kerosene burning gas turbine engine include a mixture of the nitric oxide and nitrogen dioxide collectively known as NOX. NOX emissions are significant for two completely separate reasons. The first is relevant to the problem of 'local air quality' around airports and arises because NOX is harmful when it is breathed by humans. The second is relevant to the problem of global warming and is related to the emissions in cruise. NOX affects the balance of two important greenhouse gases, namely methane and ozone.
The phenomenon of contrail formation has been studied for over 70 years. During the day, their principal effect is to reflect sunlight back into space, i.e. a cooling effect. However, at night the predominant effect is to warm the atmosphere. The global average net effect of contrails is believed to be a small contribution to global warming. The conditions under which contrails may form are reasonably well understood. First the aircraft must fly through air that is supersaturated with respect to water. Whilst this is a necessary condition, it is not sufficient since the aero-thermodynamic characteristics of the engine exhaust must also exceed certain thresholds. Notwithstanding this, the initiation process itself, i.e. the formation of the ice particles, is still not fully understood. If air is also supersaturated with respect to ice contrails can persist for longer time and then have a much greater impact on global warming than the precursor contrails. If this is correct, contrail induced cirrus may be one of aviations largest contributions to global warming.
Description of the research topics of mutual interest for both European and Chinese sides
Topic 1: Definition of strategies to reduce the impact of contrails in the global climate change
1) Conditions under which ice crystals form:
For ambient temperatures below a certain threshold (Schmidt-Appleton criterion) contrails form by condensation of water vapour onto suitable nucleation sites such as soot particles emitted by an engine as the result of mixing between exhaust and ambient air. The initially linear contrail can spread in high-supersaturated ambient conditions and evolve into contrail cirrus that may be indistinguishable from natural cirrus.
2) Contrail models:
Modelling the formation and evolution of contrails requires accurate methods like three-dimensional large-eddy simulations to capture the unsteady features of the aircraft wake, and robust microphysical models to represent the non-linear effects of ice microphysics.
3) Contrail-to-cirrus transition and implication on global climate change:
Contrail-to-cirrus transition is an important component of contrail modelling since cirrus cloud can spread to such an extent that it can be 'detected' by global models. In order to insure consistency between models, contrail-cirrus parameterizations should be developed to insure the information coming from detailed contrail simulations is transferred properly to global models in a way similar to that when developing subgrid-scale model for LES.
4) Environmental impact of contrail avoidance (trade-off between contrail effects and CO2 effects):
From an operational point of view persistent contrails could be avoided by flying into sub-saturated regions. Since this could lead to an increase of fuel consumption, a trade-off has to be found between contrail effects and CO2 effects.
5) Estimation of the global extent of aviation induced cirrus and its climate impact:
Rationale: The recently emerging meteorologically based evidence suggests that contrails and particularly contrail induced cirrus cloud may well be the largest single contribution that aviation makes to the process of global warming and, hence, climate change. Up to now, it has been assumed that CO2 emissions are aviations most important contribution to global warming with the largest amount of research being directed towards reducing aviation based CO2. However, if the real issue is aviations net contribution to global warming in the short term, a new and different strategy may be needed to reduce aviations impact. Consequently, it is necessary to gain a much better understanding of contrail formation and the potential for contrails to evolve into persistent high altitude cirrus cloud.
Topic 2: Definition of strategies to reduce the impact of NOX in the global climate change
Short description:
Current physics based models are yielding good results and allow the generation of 'data' for use in design and in the formulation of empirical models. It appears to be possible to formulate reasonably accurate 'correlation' models. However, more work needs to be done on the LES computation so that they can better inform the formulation of physics-based combustor models. On another front, we need to develop technologies to further reduce emissions in the LTO cycle in order to improve airport capacity.
Main objectives:
- To develop computer models of NOX emissions from kerosene burning gas turbine engines.
- To develop technologies to further reduce emissions in the LTO cycle in order to improve airport capacity.
List of activities:
1) Modelling the emissions and evolution of exhausts in the atmosphere using a chain of models;
2) Development of low emission combustors; and
3) Transversal action: HPC and interaction with KGT5.
2.2. KGT2 - Drag reduction technologies - CO2 emissions reduction
State-of-the-Art
The ACARE 2020 ambitious vision on CO2 emissions requires a global effort, and on many different fronts, to be achieved. A significant contribution can come from technologies for reducing aerodynamic drag. In this field many research efforts have been made and significant know-how has been accumulated in Europe and in China. Objective of this short note is to underline common trends and research paths that can be jointly pursued by Chinese and European partners.
For the sake of completeness, the trends that have emerged from the study of the state of the art are listed here:
a) Turbulent drag reduction;
b) Laminar flow technology;
c) Multi-object and Multi-disciplinary robust optimization;
d) Flow control; and
e) High fidelity CFD tools.
Description of the research topics of mutual interest for both European and Chinese sides
Topic 1: Integrated Drag Reduction Techniques for an Ultra high aspect ratio aircraft
Short description:
Research on 'Integrated Drag Reduction Techniques for an Ultra high aspect ratio aircraft', focused on HLFC wing design and turbulent flow control, combined with open rotor engine development, including configure aerodynamic optimum, laminar wing design, high-lift devices design, HLFC tech, riblets (or other turbulent drag reduction) design, high accuracy and high efficient CFD research and application, etc.
Main objective:
To research integrated drag reduction techniques on Ultra high aspect ratio aircraft, and also develop necessary numerical & experimental validation methods, aiming 2020 green aviation goal.
Outline of the approach and expected achievements:
Europe and China have a unique combination of technical expertise and industry requirement to develop, by following approaches:
- Attract technical experts to join this work. With great effort from project GRAIN, MARS and previous projects, China has fundamental team interested in this project.
- The wing layout parameter Optimum design, by developing efficient tools.
- Shock control by bump design, mainly by developing CFD design process.
- Research on riblets (multi-scale) or dimples design and simulation for turbulent drag reduction.
- HLFC wing and natural laminar v-tail to evaluate the drag reduction, by developing accurate CFD methodology.
- Introducing techniques developed in MARS on turbulent flow control.
- Limited wind tunnel tests to validate the drag reduction results and CFD design also produce data base for future use.
Then we can achieve the design methodology, develop better design process and tools, and get to know the integrated drag reduction effects. In the end we can form technique store for civil aviation further and greener development.
2) Topic 2: Turbulent drag reduction for civil transport aircraft fuselage
Short description:
The research work will focus on an integrated approach, simultaneously considering all the available and feasible technologies, to reduce the drag of fuselages or blended wing/body aircraft. The problem will be faced following a multidisciplinary approach that will allow studying it in all possible aspects and implications:
- New architectural and structural concepts and their implication on aerodynamic design.
- Passive and active devices for turbulent drag reduction.
- High fidelity computational tools and advanced MDO optimization methods for integrated aerodynamic/structural fuselage design.
Main objectives:
Develop an integrated MDO design technology aimed at the low turbulent drag fuselage design. Develop guidelines for turbulent drag reduction in fuselage and blended wing/body aircraft. Propose new concepts and technologies for turbulent drag reduction in fuselages.
Conclusions:
The choice of a common objective on which the joint research efforts may converge, among all the possible alternatives, is linked to the requirement that, in addition to being of common interest, the said field was not already been explored in depth from one of the two partners, so as to be of strategic interest to both. From this point of view, European partners, and primarily Airbus, consider that is possible to work fruitfully in the field of turbulent drag reduction. In particular, the reduction of the resistance of the fuselage might be of common strategic interest. This objective can be achieved by working on multiple fronts:
- introduction of new types of configuration for the aircraft;
- development of active and passive devices to control the flow; and
- project of micro and nano-mechanical devices for drag reduction and control of separate flows.
The Chinese partners, however, consider that there is also a strong strategic interest for the development of technologies for laminar flow, either natural or controlled or else hybrid. The European partners, while recognizing the validity of this statement, consider, however, that collaboration can develop in a more concrete and effective action on issues related to turbulent flows.
2.3. KGT3 - Noise emission reduction
State-of-the-Art:
According to noise emission regulation towards future aircraft noise, for instance Europe's Vision for Aviation 'Flightpath 2050' sets the objective of a noise reduction by 65%, relative to the capabilities of typical new aircraft in the year 2000. Such an ambitious target requires further development in the control strategy, numerical tool for mechanism understanding and prediction with accuracy and effectiveness, as well as experiment methods for validating such strategy and tools.
It has become common understanding that the engines and airframe are the main contributors to the noise radiated outward and received by those on the ground or in the cabin. Therefore, in order to reduce the aircraft noise, both two aspects need to be targeted. The airframe noise by tackling both landing gears and high lift devices, which are the two main contributors to airframe noise of an aircraft at approach as well as the engine noise addressed through its fan component, which accounts for a large fraction of the engine contribution to far-field noise, all these identified sources reveal their common property as 'flow induced'. Therefore any effective reduction strategy towards these noise issues will have close links with fluid dynamics and aero-acoustics.
After the retirement of the supersonic airliner Concorde, the current aircraft in service are all flying in the high subsonic range. However, there is a clear need from the stakeholders to have faster transportation in long distances (like between Europe and China) which necessitate completely new aircraft design. On the other hand, to answer the concerns regarding air transportation, the next generation of aviation should demonstrate significant progress in environment and low emission target. With the already highly optimized configurations, it is not possible to reach significant steps forward.
In order to be able to judge new possible configurations, efficient technologies have to be developed to aid the design phase. On the other hand, the deep understanding of the physics behind noise generation can help to distinguish between able configurations and further refine the selected versions.
Over the past decade, a significant progress has been made, sustained by a number of European networks and projects, to reach a better understanding of the physical mechanisms through which noise is produced by high-lift devices, the under-carriage and the engine fan. Direct Computational Aero-acoustics (CAA) and hybrid approaches based on Computational Fluid Dynamics (CFD) and various forms of the acoustic analogy have largely contributed to a better modelling of the sources giving rise to acoustic waves. As a result, a fair accuracy is obtained nowadays in the prediction of the acoustic far-field noise emitted by some airframe and engine components, compared with experimental data gathered by means of sophisticated microphone arrays and processing techniques.
The European partners are collaborating in several European FP7 and Marie Currie projects related to aero-acoustics as VALIANT, IDIHOM, ANADE, IDEALVENT, ORINOCO, TEENI, DREAM, FLOCON. A workshop was organized by VKI in the frame of the famous Lecture Series, 'Advanced Methods and Tools for Reducing Environmental Impacts in Aeronautics Design for Aircraft and Aero-engines'. Besides several papers were presented by the partners in international conferences such as the yearly AIAA Aero-acoustic Conference, Inter-Noise, ICSV and the two-yearly organized ISMA Conference.
Topic: Noise control methodology research, numerical tooling and experimental validation development
Main objective:
To develop noise control methodologies and necessary numerical tool and experimental validation methods, aiming future noise criteria for aircraft noise. For a number of reasons further detailed in the following sections, these technologies require further developments to tackle airframe and fan applications and deliver their benefits:
- The physics of the mechanisms responsible for the flow alteration is still insufficiently understood. This lack of understanding prevents assessing quantitatively the scalability, costs and benefits of the control approaches, once implemented on the real aircraft.
- As a result, the physical modelling of the control technology in a CFD context is still immature, while such numerical simulations are necessary to carry on effective parametric studies and optimize the control within acceptable run-times and costs.
- Further development in conceptual design or methodology advancement will face requirement and actual desire on validated technology from the industry side. Therefore numerical tools, experimental techniques and new methodologies must be validated with each other and more over, with known knowledge and techniques.
A rational choice of the most suitable/efficient approach is significantly complicated in absence of any quantitative experimental or numerical assessment of the different control approaches. There is a crucial need for new reference experimental data and systematic comparative studies of different control strategies as applied to generic configurations reflecting physics of noise-generation by the noisiest elements of civil aircraft. That systematic work will:
- Contribute to document the costs and benefits of different control approaches, and
- Form a trusty experimental database for elaborating physically consistent numerical models.
A fundamental point of interest is the development of simplified, yet reliable, representations of the effects of control devices in a CFD context. Because of the intrinsic cost of the unsteady CFD simulations that are involved in CAA and hybrid approaches, having a simplified, macroscopic description of the control device is required in order to simulate the steady and transient behaviour of the controlled flow in an affordable way. This is a pre-requisite to the optimization and eventually implementation of the control techniques in the application field. Sound absorbing porous materials for use in aerospace applications must meet stringent yet well accepted requirements concerning, especially, weight and also fire resistance. For such applications, certain types of porous materials, with their inherent multi-functionality, can be used as a part of systems engineered to reduce unwanted noise at a low overall weight.
Although the works devoted to the impedance of materials including flow effects have been conducted since the 1970s, the mechanisms underlying the acoustic response of the medium in the presence of flow have not yet been fully examined. Furthermore, recent manufacturing techniques permit producing new layouts and structures, giving increased and extended absorption characteristics with zero weight penalty and minimal manufacturing complexity. New porous materials can also be arranged in locations that were not considered before.
Talking about the topic of environmental friendly, recent development of composite material from both natural fiber and polymer has reveal its potential in better acoustic property (e.g. absorption coefficient in broad frequency band because of its hollow nature) and after life disposal. Combination of material science, engineering and manufacture process will be the way to achieve success and more environmental friendly aircraft. An important goal is therefore set to be the characterization and modelling of innovative porous materials (including natural material) and layouts (e.g. engine nacelle liner and cabin isolation panel, etc) for the suppress noise source level and propagation.
As stated by the ACARE Group, the objectives reached through a strategic collaboration with China, Russia and India are meant to benefit to European citizens, the European aerospace industry and to promote efficient international arrangements.
Generally speaking, the capacity of the Chinese partners to mobilize an important contingent of skilled researchers within the available budget envelope offers a formidable leveraging effect to multiply the benefits of the research carried out in Europe. In the other direction, a collaboration could offer opportunities to the Chinese partners to have a privileged access to the European research practices, which will facilitate further cooperation in the future.
This cooperation will also be promoting an enhanced EU market attraction to one of the fastest growing economies in the world. In the current competitive context between the European aircraft manufacturer Airbus and the American manufacturer Boeing, fostering synergies between the European and Chinese research poles may be a key to securing a leading position in the race.
Outline of the approach and expected achievements: Europe and China have a unique combination of technical expertise and industry requirement to develop:
- Innovative noise control methodology via flow control (e.g. plasma actuator, turbulent mesh, etc) for airframe noise reduction;
- Further development on engine nacelle liner to archive better suppressing property in broader frequency band via new conceptual development and application of natural composite;
- Modelling of flow induced noise with high accuracy and effectiveness yet lower computational cost, via more advanced scheme, turbulent models and HPC support; and
- Experimental technique to validate conceptual design and numerical tool as mentioned above, also produce data base for future use.
Partners:
The work will be divided into numbers of packages concerning the main content and goal, technique domain and recent readiness, and interest by joint participants. With great effort from project GRAIN and previous projects, China has numbers of institutes with large scale acoustic and flow facilities that can support conceptual development and experimental validation technique development. This ensures the frontend and finalization of research process if the philosophy was set as 'conceptual design-numerical modelling-experimental validation'.
China also has solid team lead by mainly universities, with capability and expertise in development of physics model, numerical tool and optimization methods. This ensures the numerical modelling process in entire philosophy, as powerful jet effective kneel tool.
Industry from China, with their rapid business expansion and eager requirement to future greener technology will provide valuable validation opportunities on full scale, pushing technologies developed to higher readiness level.
2.4. KGT4 - Environmentally friendly materials and structures - green materials
State-of-the-art:
In the last 2 years since GRAIN started, significant progress has been achieved on the green materials, particularly the green composite materials in a cooperative way between the European and Chinese partners. Firstly, a Chinese national team has been established led by BIAM with the key players of NIMTE and Tongji University. The team meets 3-4 times each year to discuss and exchange information of the latest development on green materials and successfully co-organized three international workshops on bio-sourced materials for aerospace and ground transportation. They presented in the same time 8-10 papers at different international conferences on advanced material development. Today, the team is the leading research body with reputation in China for its R&D of green materials and the technology.
Secondly, the team with its consortium is successfully developing bio-sourced epoxy resins and bio-degradable polylactide plastics. The materials have been evaluated and demonstrate competitive advantages against the traditional one even they are now still at the trial product phase. Besides, they are also developing natural fiber composites based on the plant fibers rich in China. As tested and demonstrated, the composites exhibit promising properties which could meet the requirements for aircraft interior structures.
European partners have proved a complete expertise on innovative technologies such as smart materials, structural design and simulation in composite materials, out-of-autoclave processing technologies, process simulation and optimization, mechanical and acoustic characterization, ageing conditions effects, surface treatments on fibers, or life cycle assessment.
The deliverable 5.2 'Report on Emerging RTD Areas of KGT4' of GRAIN project shows a complete description of the technological contributions and related publications and research projects of both Chinese and European partners.
Topic: Advanced bio-sourced composite materials for aeronautical applications
Main objective:
To develop bio-sourced polymeric resins, reinforcing fibers and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components.
Short description of the benefits to both China and Europe:
Europe and China have a unique combination of technical expertise to develop bio-sourced composite materials, aeronautical structures and related manufacturing technologies beneficial to both aviation industries. There is also a synergy between the materials development in China and the aeronautical application development in Europe that can work together to provide a complete material-based solution with minimized risk in demonstration and future application.
European and Chinese partners see advantages on carrying this project through cooperation. Chinese partners stated knowledge and expertise on the greener materials technologies, including bio-sourced fibres, resins and core-material technologies for sandwich structures, material protection technologies (bio-based fire retardants, surface treatment and resin blending technologies...) and material characterization. European partners have high knowledge and expertise on development of aircraft interiors and structures, including design, simulation, prototype manufacturing, demonstration test and comfort engineering.
Therefore, an important sharing of knowledge and expertise will be produced between both European and Chinese partners. Industrial partners showed a high interest on this project as an important step to achieve future greener composite material aircraft interiors and structures. The targeted structures are tentatively considered to be large secondary structural components and interior components.
2.5. KGT5 - High performance computing for aeronautical applications - large scale high performance methodologies with advanced it tools
State-of-the-art:
In the area of High Performance Computing (HPC) a number of critical topics must be addressed to take full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications.
Among these topics are: programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi-core CPU-GPU), fault-tolerance, cloud computing and very large datasets management.
None of these have found satisfactory solutions so far, and they are the focus of many research projects around the world. The proposal stresses the importance of investing in these areas for the mutual benefit of application development and systems performance in aerospace engineering.
The following items are the outcome of KGT5 group proposing research areas of mutual interest, focusing on the HPC items and their application to the following subjects: Airframe flight physics including: drag reduction, noise reduction, HPC innovative architecture, numerical simulation.
Topic: Large scale high performance computing
The objectives are to define common collaboration topics leveraging the use of HPC environments in order to:
- gain competitive advantages;
- deploy simulations of increasingly complex phenomena with greater physics fidelity;
- foster industrial competitiveness through advanced HPC simulation-based engineering science tools
- promote new insights gained from advanced simulations that permit increasingly realistic dynamics for deeper understanding of flight physics in real and virtual environments; and
- emphasize topics suitable for collaborative projects funded by the EC in the aeronautics field.
Target applications - Application areas of critical importance are:
- Full flight envelope characterization;
- Understanding and predicting aerodynamic flow generated noise; and
- Accurately predict and quantify uncertainty in large-scale full-fledged virtual experiments.
The areas mentioned above need contributions on the following subjects:
- HPC frameworks co-design, including hardware, systems and applications characteristics;
- Rationale: uncertainty quantification, multi-scale from the start designs, fully predictive & accurate simulations;
- Fault-tolerant algorithms, quick runtime plausibility tests, uncertainty quantification, error aware, multi-core & many-core aware algorithms;
- Virtual labs & Numerical wind tunnels;
- Verification & validation that are even more crucial than in the past;
- Deployment of high-fidelity computations as calibration tools for reduced order simulations codes;
- Path from RANS to LES simulations plus robust optimization strategies & increased predictive capability, that are allowed by increased computing power;
- Robust design, e.g. aerodynamic noise reduction, combustion in aerospace turbines; and
- Fitting new problems scale with massively parallel computers.
These topics need the following HPC challenges to be addressed:
- System resilience;
- System (hardware, systems, applications) co-design;
- Mathematical modelling;
- Numerical algorithms;
- Algorithmic challenges: programming models + extremely robust I/O and storage systems;
- Robust, scalable effective implementations of MPI;
- Combination of existing and future parallel languages, needed for incremental progress;
- Multi-stage fault-tolerance: system, hardware, application codes;
- Multi-core/many-core programming environments + intra-chip multithreaded parallelism;
- Hybrid CPU-GPU programming environments; and
- Cloud computing environments: opportunities and drawbacks.
The KGT5 GRAIN partners deem necessary to foster collaborations on the abovementioned topics by continuous efforts that involve the interested teams from both China and Europe, with particular efforts to solve the challenges related to HPC applications deployment on the petascale and future exascale super-computers.
The outcome will be technical roadmaps and recommendations on the items selected and supported by experiments run by the teams involved. All of these items are clearly technology steps to be worked out in suitable collaborative projects funded by the EC.
3) Synthesis
The final report has been prepared with contributions of European and Chinese GRAIN partners. GRAIN is an EU-China Coordination and Support Action developed from October 2010 to December 2012 in Europe and China.
This bilateral EU-China project has brought together experts from Europe (16 industrial and scientific experts) and China (13 industrial and scientific) on 'Greening of the Aircraft' areas activities according to objectives of the ACARE Vision 2020 and Flight path 2050 vision for the Aircraft reports.
The European-Chinese consortium members have been split into five (5) Key Green Technologies (KGTs) areas according to their expertise: Emission reduction of NOx ( KGT1), CO2 reduction (KGT2), Noise reduction ( KGT3), Friendly environmental Materials ( KGT4) and HPC environments for large scale simulations (KGT6).
Two Open Workshops/Forums on the above topics took place in Beijing (2010) and Barcelona (2012) with presentation of KGTs activities and invited lectures of Non GRAIN experts from Europe and China. A Short Course organized by the Von Karman Institute, Brussels in 2011) provided deeper knowledge: State of the Art on 'Advanced methods and tools for reducing the environmental impact (NOx, CO2, Noise, Materials)'
The main outcomes of GRAIN in the different areas are the following:
1) KGT1: NOx is relevant to the problem of 'local air quality' and harmful and affects methane and ozone; formation of ice particles is not yet fully understood and has a greater impact on global warming than precursor contrails. Topics of mutual interest were: conditions under which ice crystals form and contrail models. Activities were focused on future strategies how to reduce the impact of contrails in the global climate change including the modelling emissions, the evolution of exhausts in the atmosphere using a chain of models and the development of low emission combustors.
2) KGT2: CO2 emissions reduction techniques were collected and prospected on:
a. integrated drag reduction techniques for an Ultra high aspect ratio aircraft (Laminar control techniques relatively important for future transport aircraft, as well as turbulent drag reduction by controlling the Reynold stresses ( MARS EU-China project) and reliability on transition.
b. Europe and China teams have shown a unique and complementary combination of technical expertise and industry requirements.
c. turbulent drag reduction for civil transport aircraft fuselage to reduce the drag of fuselages or blended wing/body aircraft (BWB) via passive and active devices and high fidelity computational tools and advanced MDO optimization methods. Integrated MDO design technology aimed at the low turbulent drag fuselage design.
New concepts and technologies for turbulent drag reduction in fuselages have been prospected with test cases of industrial interest for both Chinese and European partners. European industrial partners consider that is possible to work fruitfully in the field of turbulent drag reduction and Chinese partners, however, consider that there is also a strong strategic interest for the development of technologies for laminar flow.
3) KGT3: Noise Emission Reduction
Engines and airframe are the main contributors to the noise radiated outward and received by those on the ground or in the cabin: the airframe noise by tackling both landing gears and high lift devices and the engine noise addressed through its fan component. Effective noise reduction strategies have close links with fluid dynamics and aero-acoustics. A significant progress has been made, sustained by a number of European networks and projects, to reach a better understanding of the physical mechanisms through which noise is produced by high-lift devices, the under-carriage and the engine fan. CFD and various forms of the acoustic analogy have largely contributed to a better modelling of the sources giving rise to acoustic waves.
European partners are collaborating in several European FP7 and Marie Currie projects related to aero-acoustics as VALIANT, IDIHOM, ANADE, IDEALVENT, ORINOCO, TEENI, DREAM, FLOCON
Topics investigated during the development of GRAIN:
- developing noise control methodologies and necessary numerical tools and experimental validation methods, aiming future noise criteria for aircraft noise.
- passive or active flow control hence noise generated e.g. plasma actuation, turbulence screens engine noise control through advanced liner concept and using more acoustic effective yet environment friendly material to archive better cabin acoustics have shown their potential
The physical modelling of the control technology in a CFD context is still immature. There is a crucial need for new reference experimental data and systematic comparative studies of different control strategies as applied to generic configurations reflecting physics of noise-generation. Europe and China have a unique combination of technical expertise and industry requirement to develop innovative noise control methodology via flow control (e.g. plasma actuator, turbulent mesh, etc) for airframe noise reduction; modelling of flow induced noise with high accuracy and effectiveness yet lower computational cost, via more advanced scheme, turbulent models and HPC support, experimental techniques to validate conceptual design and numerical tools, produce data base for future use.
4) KGT4 - Environmentally Friendly Materials and Structures
Significant progress has been achieved on the green materials, particularly the green composite materials in a cooperative way between the European and Chinese partners (BIAM, NIMTE and Tongji University, 8-10 papers presented at different international conferences on advanced material development). KGT4 partners have shown a complete expertise on innovative technologies (smart materials, structural design and simulation in composite materials, out-of-autoclave processing technologies, process simulation and optimization, mechanical and acoustic characterization, ageing conditions effects, surface treatments on fibers, or life cycle assessment (LCA) .
Topics investigated: Advanced bio-sourced composite materials for aeronautical applications including the development of bio-sourced polymeric resins, reinforcing fibers and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components. Bio-sourced materials will meet or partially exceed the mechanical properties and reliabilities available from standard petroleum-based materials.
Preliminary research and development on natural fibre composites and bio-based polymers have shown that the specific mechanical properties of the bio-sourced materials can partially compete with the petroleum-based resins. A synergy between the materials development in China and the aeronautical application development in Europe can work together to provide a complete material-based solution with minimized risk in demonstration and future application. Industrial partners showed a high interest on this project as an important step to achieve future greener composite material aircraft interiors and structures.
Among future activities identified by KGT4 members : Natural fiber composite technologies, Advanced core technologies, Bio-based resins for structural application, Bio-degradable resins for structural applications, Ageing behaviour improvement technologies, Development of the novel hybrid fire retardants, Development of aircraft structures using green composites, Development of greener aircraft interiors, Greener manufacturing, Life Cycle Assessment (LCA)
5) KGT5 - High Performance Computing for Aeronautical Applications
This group investigated the full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications including programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi-core CPU-GPU), fault-tolerance, cloud computing and very large datasets management. Multidiscipline applications were focused on airframe flight physics including: drag reduction, noise reduction, HPC innovative architecture, numerical simulation.
Common collaboration topics leveraging the use of HPC environments:
a) deploying simulations of increasingly complex phenomena with greater physics fidelity
b) promote new insights gained from advanced simulations that permit increasingly realistic dynamics for deeper understanding of flight physics in real and virtual environments
The identified application areas of critical importance are:
a) full flight envelope characterization;
b) the understanding and predicting aerodynamic flow generated noise,
c) Accurately predict and quantify uncertainty in large-scale full-fledged virtual experiments
d) Virtual labs & Numerical wind tunnels
e) Deployment of high-fidelity computations as calibration tools for reduced order simulations codes
f) Path from RANS to LES simulations plus robust optimization strategies & increased predictive capability, that are allowed by increased computing power,
g) Robust design, e.g. aerodynamic noise reduction, combustion in aerospace turbines
Among the HPC challenges identified:
a) programming models + extremely robust I/O and storage systems
b) robust, scalable effective implementations of MPI
c) multi-core/many-core programming environments + intra-chip multithreaded parallelism
d) hybrid CPU-GPU programming environments
e) cloud computing environments
Particular efforts are needed to solve the challenges related to HPC applications implemented on the petascale and future exascale super-computers.-
4) Conclusions and further actions
The highly ambitious vision 'Flightpath 2050' demands a global and multidisciplinary effort for achieving the identified targets. Significant contributions for reaching these targets can be obtained by developing the corresponding greening technologies. In this context research efforts have been made until now in Europe and in China and significant know-how has been accumulated. The main objective is to identity the future research areas for greening technologies that are of mutual interest of aviation stakeholders from China and Europe and can be jointly pursued in the future.
Major ingredients of the future research areas (emissions, CO2, Noise, Friendly Environmental materials and HPC environments for large-scale simulations) for greener technologies that are of mutual interest of aviation stakeholders from China and Europe have been identified.
Chinese -European teams working on the above areas have integrated and complemented expertises during the development of GRAIN, either with e- sessions or meetings in Europe open workshops. Motivated by excellent mutual scientific and friendly human understanding these EU-China teams will continue to deepen collaboratively their knowledge in future research EU-China projects.
Strategic Guidelines for Future Technology Development
Based on the detailed stat-of the-art studies developed by each of the Key Green Technology group the following main four (4) technology streams are identified for future actions:
1) Airframe configuration oriented technologies;
2) Environment and engine technologies;
3) Material and structure technologies; and
4) Numerical simulation and wind tunnel testing enabling technologies.
Airframe configuration oriented technologies
Several technology actions are considered here oriented to reduce airframe drag (induced and viscous) and weight. These are:
1) Innovative configurations for high aspect ratio designs;
2) Turbulent drag reduction technologies; and
3) Distributed propulsion and related boundary layer ingestion technologies.
Environment and engine oriented technologies
Several technology actions can be considered here for more efficient low noise and NOx engine together with the necessary activities for ice crystal, contrails and other particles modelling. These are:
1) High/ultra-high by pass ratio engine technologies
- Engine architecture, materials for higher temperature combustor, development of low emission combustors
- Develop noise control methodologies and necessary numerical tool and experiments for validation methods, for engine noise.
2) Environmental aspects
- Understand the fundamental of contrail physics: science of initial formation of the contrail, the evolution of the linear contrail and the conditions in which a linear contrail evolves into a cirrus cloud
- Develop models that can be used to assess the impact of the global aircraft fleet on global warming.
- Develop new strategies for minimizing aviations total climate impact
- Modelling the emissions and evolution of exhausts in the atmosphere using a chain of models
Materials and structure technologies
The trend here is to develop bio-sourced polymeric resins, reinforcing fibres and honeycomb papers for design and manufacturing of aeronautical composite materials as well as aircraft secondary structures and interior components.
Numerical simulation and wind tunnel testing technologies
- Advancement of flow diagnostic tools (PSP, TSP, 3-D TomoPIV etc) to assist code development and validation.
- For numerical simulation a number of critical topics must be addressed to take full benefit of the rising petascale and future exascale super-computers by large-scale multi-discipline applications. Among these topics are: programming environments, models for multi-discipline and multi-scale problems, I/O performance, hybrid architectures and distributed frameworks (multi- core CPU-GPU), and very large datasets management.
- Physical modelling for separated unsteady flows.
Potential Impact:
Scientific prospects
The activities in the GRAIN CSA open a wide range of scientific and technological prospects for future cooperation between European and Chinese organizations in the development and validation of new green technologies for aeronautical applications. Access to state of the art information on RTD activities in China and in Europe on greener technologies opens many opportunities for the development of new and enhanced methods aiming to the emission reduction, noise reduction and green materials which will enable to reduce the environmental impact of aircrafts and air transport.
Technological aspects
The technological prospects will derive from the new modelling possibilities of experimental and computational advanced design of civil aircraft vehicles taking into consideration many multidisciplinary effects currently not strongly accounted for in practice and mainly related with environmental issues. The GRAIN Guidelines will define the strategic lines and methodologies (both, numerical modelling and experiments) to be developed in the near future for the reduction of environmental impact of air transport. These guidelines will bring flags and added values as a basis for setting up new RTD projects.
Contribution to EU policies
The GRAIN proposal will be co-funded on a symmetric basis by European Commission for European partners and by Chinese Authorities (MIIT) for Chinese partners as it is shown by an e-mail from AVIC, attached in Annex.
This project aims to enhance the open cooperation between Europe and China in the field of aeronautic research and engineering. Indeed this goal was achieved of the conclusions of the EU-China workshop in Aeronautics held in Beijing on April 15 2005, also confirmed on the latter AEROCHINA 2 project final meeting in Brussels in September 2009.
AEROCHINA 1 & 2 CSA projects have been a very good example of leverage successful networking projects that were coordinated by CIMNE with the participation of many of the GRAIN partners. The contribution of both AEROCHINA projects to EU policies has been demonstrated trough the production of different collaborative development topics that has been used for the definition of a FP7 Coordinated Call in 2010.
The specific scope of the GRAIN proposal also fits within several aspects of the European Union policies. Improvement of the design, analysis and validation tools will help to build safer and more competitive aircrafts with improved environmental features (fewer emissions. Indeed producing safer and cleaner airplanes is one of the targets to guarantee better protection of passengers. The enhancement of greener aircraft design, manufacturing and maintenance is one of the key aspects for a sustainable European aerospace industry meeting the challenges and demands of the air-transport sector for the next decades.
The objectives of the GRAIN proposal fit with the guidelines and recommendations proposed in the vision for 2020 EC report on European Aeronautics. The response to issues of public interest is a key element of the 2020 Vision Agenda including multidisciplinary problems such as noise reduction, emission reduction and safer air transport and affordability.
In summary, the joint activities of the GRAIN project will be of value for helping to achieve the goals of the research agenda in the European aeronautics sector in the next two decades. As clearly specified in the 2020 Vision report only 'an integrated research approach can provide the basis for satisfying societys need and ensuring European leadership in the global aerospace market by 2020'. Helping to build this integrated research scenario through a better cooperation between European and Chinese organizations in the solution of environmental issues in aeronautics is one of the main goals of the GRAIN proposal.
The successful development of the GRAIN project will open new opportunities for creating employment in a number of strategic lines. Thus, by having access to state of the art computational methods and software for a better design and production of aeronautic vehicles in a multidisciplinary environment, the need for skilled engineers will increase the demands for jobs. Similarly, new training and education programs will have to be implemented for developing the skills of practising and newly graduated aerospace engineers into the possibilities of the new methods for multidisciplinary design. This will also contribute to the preservation and creation of employment in Europe.
The interaction between partners from different organizations in Europe and China (aeronautics/aerospace industries, RTD centres, universities and international associations) will lead to an exchange of technical and policy ideas and personnel which will help towards making more attractive the work in these fields.
The GRAIN data will also find application in markets different from the aeronautic sectors that also need the computational multi physics transport technologies (i.e. turbo machinery, civil construction, naval architecture, automotive industrial forming processes, etc.). Transfer of the GRAIN greener multi-physics technology to these sectors through adequate disseminating actions (i.e. lecture series, road maps, workshops, conferences, publications, etc.) will help to create new attractive cooperative RTD scenarios and business opportunities for cooperation between different sectors and this will also contribute to the creation of new jobs.
Environment
The 2020 Vision aims to make European Aeronautics a global leader in the world market with safer, less noising and less polluting aircrafts. The GRAIN CSA activities and outputs will contribute towards achieving these goals by preserving the environment in a number of ways. First, one of the main goals is the improvement on the methods which enables the emission reduction. In addition, a better aerodynamic and acoustic design of aircrafts, plus the use of cutting-edge materials which will reduce the total weight of the aircraft will also be beneficial for reducing the emission of external and internal noise. The development of emission and noise reduction techniques is one of the goals of the 2020 vision report.
Likewise, a better understanding of flow turbulence and turbulence/chemistry interactions will contribute to a reduction of fuel consumption and pollution emissions. In addition, a better design of aircraft and structures (obtained by accounting for all the couplings and interactions of the participating physical phenomena) will ensure a longer durability of components and integrated aircraft vehicles. Finally the modelling of uncertainties in analysis and design software will contribute to reduce significantly margins which warranty the maintenance of performances and stability within real operations of aircraft. This will invariably contribute to extending the life cycle, thus, reducing the environmental impact of maintenance and replacement.
Quality of life, health and safety of the citizens
The objectives of the GRAIN proposal respond to a number of societal needs. Indeed, the design of safer, cleaner and quieter aircrafts has a direct impact on the quality of life and safety of citizens.
The GRAIN multidisciplinary data will be an essential contribution for developing new methods for the understanding of flow/turbulence and chemistry interactions, the better design of aircraft structures reducing noise emission, fuel consumption, fuel emissions and for extending the life of aircraft vehicles. All these aspects will have a very positive impact on the quality of life and health of citizens.
Indeed the design and production of aircraft structures with better endurance limits will contribute to reduce the technological risks involved in aircraft construction and operation. This will also have a very positive effect in the overall safety of aircrafts and, hence, on the safety of citizens.
GRAIN will confirm the hopes of proposers from new identified collaborative methods and tools for the design new civil and business aircraft in terms of performances, environmental problems and safety to issue a roadmap leading to a significant improvement (30% or more) over the existing range.
Project website:
http://www.cimne.com/grain
Technical Contact in CIMNE
Prof. Jacques Periaux, jperiaux@gmail.com
Prof. Gabriel Bugeda, bugeda@cimne.upc.edu