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EFficient FAn

Final Report Summary - EFFAN (EFficient FAn)

Executive Summary:
On an electrical ECS pack, outside air is used to remove heat from the cooled system. The outside air flow is generated on ground thanks to a vacuum device. The present subject deals with electrical fan solution used as vacuum device for ram air flow generation. The challenge of optimizing such a component for this application is double.
First, from aerodynamic point of view, the fan shall be capable to generate pressure drop whatever the flow without surge issues. Indeed, the ram air fan is used to suck main air flow through ECS pack main heat exchanger for cabin cooling and in the meantime to suck small amount of flow through ECS pack electrical motor stator for cooling. Due to ECS control logics, the fan shall be also capable to ensure ECS motor stator cooling without any flow from main heat exchanger. In this case it shall provide the same pressure rise with a very limited flow.
Then, the fan is installed downstream of the ECS main heat exchanger. Therefore, high temperature air can enter the fan and specific concept shall be implemented for fan integration to enable fan mechanical and electrical subpart cooling.
Finally, technology and solution selected to comply with these last constraints shall minimize impact on performance efficiency and component reliability and availability so as to achieve global ECS objectives.
Considering these objectives, a new fan concept has been selected from available bibliographic and consortium expertise, and designed using the consortium skills in deep fundamental fluid mechanics and heat transfer knowledge (Universitat Politècnica de Catalunya- UPC ), advanced CFD tools and aerodynamic know-how (Termo Fluids - TF) and engineering capacities of a fan manufacturer (LMB SAS).
After a careful selection of anti-surge technologies based on state of the art carried out within the first project period, some predesigns have been numerically tested and aerodynamically analyzed (WP2). A final modeling of the ram-air fan and the consequent prototype has been designed, constructed and successfully tested at both flow range conditions (WP3). The numerical results and the experimental data have assured that final proposed solution avoid surge problem under both flow conditions initially expected.
In a similar manner, a thermal analysis of the selected electric motor coupled with the fan designed has been thermally analyzed. The thermal design has been numerically modeled and experimentally tested under high temperature conditions in a climatic chamber. The fan thermal validation has allowed to numerically check the temperature level at the actual conditions indicated by the Topic Manager in the initial project requirements.
In conclusion, an adequate efficient fan design has been obtained to cover at the same time, both high and low flow rate working conditions and high inlet air temperatures. Thus, LMB has now this new efficient fan design, TF has improved its in-house CFD numerical tool capable to predict the surge effect under numerical simulation of fans, while UPC has developed a detailed thermal model capable to analyze thermal effects in electric motor driven fan configurations. Finally, LTS has acquired the know-how and the technological readiness to drive the ram-air flow with a wide flow spectrum fan, thus covering the initial objective of cooling the ECS main heat exchanger or alternatively the ECS electrical motor stator.

Project Context and Objectives:
The conventional aircrafts engines, not only produce thrust to propel the aircraft, but also deliver electrical, pneumatic and hydraulic secondary power. The main secondary power and extra fuel consumer is the environmental control system (ECS), which is the responsible of providing a comfortable close environment for a given payload (people, goods and living matter) by keeping temperature, pressure and humidity within the required limits. ECS can reach the 75% of non-propulsive power on cruise.
With the aim of reducing the direct operating costs in the aircraft sector by means of decreasing maintenance costs and minimizing fuel consumption the adoption of all electric ECS has been considered as an alternative to the conventional bleed driven ECS. In an all- electric ECS the air that is used to cool the payload is air taken directly from outside, instead of bleeding it from the compressor (as in a conventional ECS system). Moreover, the ECS pack is electrically driven, what introduces the necessity of cooling such electrical motor. Boeing adopted the all-electric ECS in the B787 aircraft, being the first commercial aircraft using this technology.
When aircraft is on ground a vacuum device is needed for ram air flow generation. According to Topic Description the challenge of optimizing this fan for this application is double. First, from aerodynamic point of view, the fan shall be capable to generate pressure drop whatever the flow without surge issues. Indeed, the ram air fan is used to suck main air flow through ECS pack main heat exchanger for cabin cooling and in the meantime to suck small amount of flow through ECS pack electrical motor stator for cooling. Due to ECS control logics, the fan shall be also capable to ensure ECS motor stator cooling without any flow from main heat exchanger. In this case it shall provide the same pressure rise with a very limited flow.
In the present project a smart combination of numerical and experimental tools has been used for the design of a ram-air fan solution in order avoid or suppress stall and surge problems at low flow conditions. A similar approach has been employed to obtain an adequate solution for the ram-air fan electrical motor cooling at high inlet air temperatures.
After having an overview to the project main objectives within the framework of the more electric aircraft, the specific objectives for the whole period of the project have been:
WP1 Project management.
Control the tasks related to the technical coordination of the project, as well as the administrative and financial management within the consortium. Fulfillment of the reporting obligations towards EC and ITD members. Cover activities regarding the dissemination, exploitation and IPR management.
WP2 Selection of a technology for the solution of fan surge at low flow conditions.
On P1, Task 2.1 has provided a complete bibliographic study with proposal of the most promising technologies to solve the surge design problem, indicated on Deliverable 2.6. On P2, Task 2.2 a pre-design based on aerodynamic concepts and numerical simulation cases have been carried out and are detailed on Deliverable D2.7.
WP3 Fan surge technical solution.
This WP has been fully developed within P2. This WP has been mainly oriented to the validation of the proposed aerodynamic solution by means of numerical simulations and laboratory test on a prototype. Task 3.1 is conceived for numerical simulation at different levels in order to refine the ram-air fan predesign and to confirm the new design ability to suppress the fan surge problem, (reported in Deliverable D3.8) while Task 3.2 has been focused on prototype manufacturing, described in Deliverable D3.9. Finally Task 3.3 has devoted on experimental test and validation comparisons, as it is explained in D3.10.
WP4 Fan thermal management.
Based on analysis and development of a solution enabling thermal management of the fan in hot air condition, Task 4.1 is devoted to the thermal analysis of the problem by a bibliographic search and identification of innovative ideas, finishing with the selection of the best concept. Deliverable 4.11 presents the bibliographic search, while D4.12 presents the selected solution/technology and the available software tools. This task started on P1 and has finished on P2.
During P2, Task 4.2 has been devoted to the detailed analysis of the actual fan thermal management concept to have a detailed and deep analysis. In a first phase, the preliminary design was based on a mixed flow fan (described in D4.13) but finally due to space and efficiency reasons, the design has been changed to an axial one (described in D4.14). During Task 4.3 the final solution has been tested not only to assure the thermal solution, but also to provide a full heat transfer physics understanding (details in D4.15).

Project Results:
EFFAN project was initially expected to be developed during a period of 18 months, staring on February 2014. After the first 3 months of the projects, and due to the unfortunate situation of Baltogar company partner bankruptcy, there was a stop on project work since May 2014 until May 2015 (12 months) looking for Baltogar partner replace, who finally was found with LMB company. After EFFAN amendment approval, the project was expected to restart on May 2015. However, REA validation of LMB company and some bureaucratic aspects obliges to finally restart the project on September 2015 (4 months later than was initially expected). A final amendment was needed to enlarge the second period of the project that finally started on September 2015 to end on September 2016 (both months included).
Thus, the final real period of EFFAN working project has been a first period (P1) from February 2014 to April 2014 (3 months) and a second period (P2) from September 2015 to September 2016 (12 months) a total period of 15 months within a period of 32 months.
A first period was reported in a Periodic Report P1 of 3 months February 2014 to April 2014, with UPC, TF and Baltogar as project partners. While a second period has been reported in a Periodic Report P2 of 12 months September 2015 to September 2016 (with a gap period of 16 months from May 2014 to May 2015 without partner replace, another gap period of 4 months from May 2015 to September 2016 due to bureaucratic problems and one amendment of two months extension from July 2016 to September 2016).
The Periodic Report P1 was mainly covering: mainly TASK 2.1 of State of the art on anti-surge technologies and a first part of TASK 4.1 of Fan thermal analysis. Within this P1, a deliverable D2.6 of anti-surge technologies and a D4.11 of bibliographic search of motor cooling technologies and high air temperature fan solutions were carried out.
The Period Report P2 has covered: TASK 2.2 on Predesign of several aerodynamic concepts, detailed within deliverable D2.7 of low flow range fan technologies description and selection; TASK 3.1 for the modeling of the ram fan air at low flow conditions within deliverable D3.8 of prototype fan design report, TASK 3.2 of the fan prototype (D3.9) and TASK 3.3 of fan test results and validation report (D3.10). TASK 4.1 and TASK 4.2 of fan thermal analysis and design were carried out and reported within D4.12 of fan thermal management solution, D4.13 preliminary design, D4.14 fan thermal solution, while TASK 4.3 finished with a numerical and experimental comparison of test results of TASK 3.3 together with numerical comparisons within D4.15 of thermal test performance validation.
The milestones of the project have been accomplished according the objectives initially planned:
MS4 a fan surge solution has been numerically obtained.
MS5 a fan prototype to avoid the surge problem has been designed; MS6 a fan prototype according the previous design has been constructed; MS7 the fan prototype has been tested for both high and low mass flow rates assuring the surge problem is avoided, thanks to anti-stall solution proposed, designed and proved.
MS8 a fan cooling solution is implemented based on LMB models; MS9 the actual design has been tested within the same prototype; MS10 a numerical simulation tool has predict how the actual design works, MS11 the fan prototype has been tested and validated according the simulation predictions.
A PDF document is attached with 25 pages including Figures and Tables that explains in detail the S&T summary description provided.

Potential Impact:
The EFFAN project has succeeded in its main target, the design and performance validation of a new fan to cover the specific necessities that appeared with the more electric aircraft ECS design. The developed fan covers the expected wide airflow range without stall/surge issues, lowering the noise comparing to a standard fan, as having much less flow instabilities. Moreover, the efficiency of the fan is not affected by the integrated anti-stall device. On the other hand, the electric motor that drives the fan has a design capable to withstand the high air inlet temperatures required by the Topic Manager, by means of high temperature components, avoiding the introduction of complex cooling systems, alternative cooling airflow means, etc.
The success in covering the project requirements means that the project can really have an impact on the final new electric-ECS designs, providing a reliable (no instabilities, withstanding high temperatures without adding complexities) and efficient (same fan efficiency, one single fan to cover two very different tasks) component to cover such a critical task (cooling of air cycle machine, cooling of electronic devices, etc.).
Once seen the specific impact of the new fan at ECS design level, let us analyse the impact from a more general perspective. Thanks to its impact on the aircraft implementation of the electric ECS, the EFFAN project will have a high contribution to the European competitiveness with a potential for a reduction of energy consumption and environmental pollution while developing a new ram-air fan to be integrated in the ECS system with large possibilities of industrial and sector-wide applications.
The effect of aircraft emissions on the environment is complex and not fully understood. In absolute terms, it is clear that aviation will have a significant effect on climate change, greater than that suggested by the industry’s CO2 emissions alone. Worldwide air passenger traffic is forecast to grow by 4 to 5% per annum. This growth needs to be met whilst minimizing its negative impact on the environment. Air travel in 2050 will need to look very different than that of today. For the mitigation of the negative environmental effects, the target for 2050 is to employ technologies and procedures for reducing a 75% the CO2 emissions per passenger kilometre, and a 90% of the nitrogen oxide (NOx) emissions. To achieve such a goal, a large number of solutions and approaches must be utilized. As it is well known, the impact of increasing fuel prices is fostering an additional effort in the aircraft industry in order to reduce the weight of the airplanes and to improve the efficiency of the main engines and the auxiliary equipment as well. Despite the continuous improvement of turbofan and turboprop engines efficiency, the rapid growth of air travel in recent years contributes to an increase in total fuel consumption. In the European Union, greenhouse gas emissions from aviation increased by 87% between 1990 and 2006. Today, aviation contributes to approximately 2% of the total man made CO2. There are various factors that contribute to the release of GHG form aviation including frequency of travel, type of fuel, aircraft design, among others.
When focusing on the environment, the main targets for the year 2020 as defined in the Strategic Research Agenda (SRA) for aeronautics in Europe –the SRA of the Advisory Council for Aeronautics Research in Europe (ACARE), the European Technology Platform for aeronautics- are the following:
• 50% reduction in CO2 emissions per passenger kilometre (i.e. 50% reduction in fuel consumption in the new 2020 aircraft compared to 2000)
• 80% reduction in NOx emissions
• 50% reduction of perceived aircraft noise.
The project appears to be in line with the environmental targets of the SRA of ACARE. On the other hand, the Clean SKY SGO initiative aims to meet the increasing social demand to reduce fuel consumption, emissions and noise through the adoption of a new approach when designing systems. More specifically, SGO environmental objective consists in the reduction of NOX and CO2 emissions (between a 5 and 9% of reduction) through an improved energy management and systems weight reduction.
While this project does not directly tackle all these issues, it is fully in line with the strategic objective of both the SRA of ACARE and the SGO initiatives, as it will firmly contribute to the reduction of emissions, contributing to the European Competitiveness. In fact, the project has acoomplished with the objective to develop a new ram-air fan integrated in the ECS system, which has a high degree of importance to improve the energy efficiency of the system as a whole. Two main aspects have been identified regarding energy efficiency of the fan. The first one refers to the improvement of the fan at low-speed conditions where fan surge has been eliminated. Any reduction of these instabilities would have a clear impact on the fan efficiency at those conditions. The advanced and detailed analysis of the fan fluid-dynamic and turbulence behaviour would also introduce efficiency improvements in the rest of flow conditions where the fan is expected to work. The second aspect to be addressed during the project that has an impact on energy efficiency of the fan is related with the thermal management of the corresponding electrical motor. Apart of assuring the thermal control at the high temperature conditions, the proposed improvement of the cooling process by the detailed study carried out can also reduce the motor core temperature, which has a direct impact on its energy efficiency. Published works indicate an achievable improvement in efficiency of around 1.5% [Yoon et al., 2002]. The conclusions on this electric motor would have obviously an impact on the rest of electric motors that the all-electrical aircraft design integrates in the system.
In relation to the environmental pollution, as previously mentioned, the in-flight civil aircraft is estimated to contribute to global CO2 emissions at around 2%. However, non-CO2 contaminant effects may increase the total impact for high-altitude flights near or in the stratosphere. The Intergovernmental Panel on Climate Change (IPCC) has estimated that aircrafts are responsible for around 3.5% of climate change of anthropogenic origin (including both CO2 and non-CO2 effects). The IPCC estimates are that aviation’s contribution could grow from 5% to 15% of the total contribution by 2050 if action is not taken to reduce these emissions.
From a general CleanSky point of view, it is interesting to highlight that the fact that the main engines could work in a more stable manner in the all-electrical aircraft would probably derive in an optimisation of the combustion processes and therefore in the reduction of NOx and other contaminants emission levels. Considering previous statements, it is clear that any measure that can contribute to an improvement in the energy efficiency of the aircraft components would derive in a reduction in the CO2 emissions level. Then, related specifically to current project, the ram-air fan integrated in the ECS system has an importance in order to improve the energy efficiency of the system as a whole. Two main aspects have been obtained regarding energy efficiency of the fan: i) the improvement of the performance by surge-condition mitigation; ii) the assess of motor performance by actual expected temperature conditions.
Apart from efficiency/emissions aspects, there is another important issue related to pollution that should be analysed: noise. The Clean SKY SGO initiative objective in terms of noise consists in its reduction between -2 to –5 dBA (in phase of approach/landing) and -2 to -3dB (in phase of take-off/climb). The project is in line with these objectives as the reduction/mitigation of the surge effect has an impact in this sense, as it permits avoiding conditions with higher pressure/velocity non-uniformities and less instability that generate noise. CFD work on the fan blades around surge problems is also detecting noise sources and developing ways intended for its reduction. The project contributes to the European transport policy which is in line with the Euro 2020 initiative in working towards “resource efficient Europe”. This is achieved by facilitating economic progress, enhancing competitiveness and offering high quality mobility while using resources more efficiently. The project has certainly enhanced European competitiveness and facilitate economic progress as the innovative ram-air fan, developed in the project, has a high degree of importance to improve the energy efficiency of the system as a whole. Europe is home to approximately 448 airlines and 701 commercial airports which in 2010 supported 606 million passengers allowing the free movement of people and goods across borders. The European Air Transport sector has an annual turnover of more than € 95 billion and employs over half a million people directly with another 2.6 million indirect jobs. Research and development helps develop Europe’s competitive advantage - on average almost 7 billion euros are reinvested every year in civil aeronautics R&D. The European Vision for Aeronautics and Air Transport in 2020 set targets to facilitates needs of society, while maintaining European global leadership in aeronautics especially against the US market. Competition to provide the products and services to meet that growth is also intensifying. This competition comes not just from traditional rivals, such as the US, but increasingly from strong challengers from Brazil, Canada, China, India and Russia.
With the new innovative ram-air fan developed while improving the whole system energy efficiency and reducing CO2 emissions, the project can highly contribute to the RTD European targets for strengthening the European competitiveness in the Aeronautics sector. Therefore, the project’s results will have an important number of economic contributions The synergies created during the project, and the obtained fan design, have an important economic potential impact as enhancing the competitiveness of the Topic Manager (having an electric ECS with a single ram-air fan to cover very different cooling necessities), and of fan manufacturer LMB (developed a ram-air fan with outstanding capabilities in terms of stability and high temperature operation).
Since ram air fan are not included in the ECS baseline configuration for large aircraft, the project results will have major impact on the regional aircraft market. Regional aviation plays a very important role in Air Transport System. Regional fleet (9000 aircraft) accounts for 37% of world fleet. About 42% of the total departures are to attribute to Regional air transport while about 26%of the total flown hours are to attribute to Regional air transport. Regional carriers typically operate aircraft, such as regional jets and turboprops, with fewer than 120 seats, on short to medium-haul routes. Regional airlines mission is focused on operate aircraft to provide passenger air service to places/cities/communities without sufficient demand to attract mainline service. The regional aircraft market continues to be a key growth sector of the airline industry. Taking into consideration traffic developed by regional aircraft (capacity ranging in the 30-120 seat segment), in the last year more than 660000 million ASK (Available Seat Kilometre) were offered worldwide. Only in Europe regional carriers were able to offer more than 120000 million ASK to passengers interested short-time intra-continental connections with average distance of 320NM (about 600 km). Slight less than 200mln people in the last year flew on regional aircraft within European network. Regional traffic is expected to triplicate in the next 20 years. It is forecasted about 9300 new regional aircraft (both turboprop and jet) will be delivered worldwide in the next 20 years for a value of about €280 Billion (EC 2012), avg. €14Billions per year. Therefore, with a turnover of 110 billion euro, the European Regional Aviation market offer a huge potential for the strategic impact and market up-take of the project results.
In addition, this project has a great potential in extending the conclusions or improvements achieved in the design of aircraft fans to other applications where fans are being used. It is clear that this equipment is broadly used in a great quantity of applications: ventilation, air-conditioning, refrigeration, process industry, automotive industry, etc. It is expected that know-how generated under the severe and exigent conditions found in aircraft operation could be implemented in other applications. For instance, the reduction of surge problems and related noise will be for sure crucial in low-noise applications such as domestic air-conditioning using variable speed fans. On the other hand, any improvement in the design of the cooling system of the electrical motor would have an impact not only in the fan industry, but also to a much wider market as electrical motors are used in many other applications (electric vehicles, pumps, industrial machines, automation equipment, etc.).
Finally, the project will have significant secondary impacts through positive interactions with other programmes of work within the areas of aeronautics. Due to the initial partners’ situation, the project extension and the extended deadlines, it has not been possible to have results until the end. At current stage, when we have finally a successful fan design and simulation tools, the partners will be able it to establish relations and synergies outside of project consortium. In a similar way, different proposals of conferences, papers and fairs are expected in the next few months after the end of the project.
Dissemination and exploitation of the results
The dissemination of the results of the project is an important action once the intellectual property has been protected, in order to reach the widest possible impact to facilitate the take-up of the new technology. Dissemination has tried to be promoted at all levels, in order to spread, in accordance with IPR restrictions, the main innovative aspects which evolve during the development of the project. However, and due to all problems carried out (Baltogar bankrupty, the different extended period of time needed, and the impossibility to have some results to be disseminated until the end of the project with the prototype tested), has not allowed to have a lot of dissemination activities and only one conference paper from UPC and TF has been developed during this period and mainly focused on numerical aspects.
A Dissemination Plan has been developed. The purpose of the Dissemination Plan was to provide a formal planning document for using and disseminating knowledge throughout the project. The plan has tried to facilitate the common understanding of the aims of the dissemination activities, and assure the dissemination does not interfere with the IPR management but serve it. However, as it has been explained dissemination purposes has been postponed until now, where different conferences, papers and fairs are planned for the next few months.
The website has been created at the beginning of the project. In fact, it is assumed that the results will not only be interesting to the scientific community but also to a great number of SMEs and public aeronautic actors. The dedicated website has not produced an extensive record of all publications and communications originated on the course of the project due to the problems explained above. However,. a public area containing general information on the project, useful links to the EC services, etc., has been continuously updated with the public results obtained, deliverables, news for communication of events. No workshops and conferences related to the project have been possible, although contacts to allow the website visitors to have a direct link to the Consortium has been available.
On a scientific level, the dissemination activities are now ready to be carried out through publications in specialized journal of aeronautics/aerospace and thermal engineering related journals – for example, AIAA Journal, Computer&Fluids, Journal of Fluid Mechanics, ASME Journal of Turbomachinery, IEEE Transactions on Industrial Electronics, IEEE Transactions on Energy Conversion, Applied Thermal Engineering, Heat Transfer Engineering, etc.
The project will address only publications that reach a wide spectrum both of the scientific and technical community. The results of the project are now ready to be presented at different events (workshops, technical conferences, fairs and exhibitions) organized by the
consortium and in other potentially interesting events that could be planned by interested organizations. In particular, the consortium has already planned to attend and present partial project results to the following events: Aerodays, Paris Air Show, Toulouse Air Show, including IEEE Aerospace Conference, Farnborough International Air Show, etc.
On a second level, wider dissemination will be achieved via a more general strategy for attaining a broad coverage of the project to a wide range of European aeronautic public and private actors. This strategy includes the following activities:
- The diffusion of knowledge in cooperation with European organisations, such as the Advisory Council for Aeronautics Research in Europe (ACARE), the European Technology Platform for aeronautics and the Aerospace and Defence Industry Association for Europe (ASD Europe). Through the websites and annual meetings of these organizations, the present project can have a direct link with their related scientific community, public aeronautics actors, industry, and affiliations. In general, any useful contacts and coordination/networking with national programs, industrial associations and related consortia within and outside Europe will be pursued in the aeronautics sector.
- Direct mail to targeted organisations and groups, based on target groups selected from relevant organizations for the use and spreading of the research results, as the existing aeronautic clusters.
Exploitation of the project results will be conducted by identification and protection of generated IPR, market needs assessment and communication with the stakeholders. In this case, each one of the partners in the consortium has made a significant effort in order to define as detailed as possible their exploitation interests and possibilities. For the results obtained, ownership, protection and use will be considered in detail. So, the basic IPR framework agreed by the partners considers: i) a final ram fan air prototype to be exploited by LMB and an updated numerical simulation tool for aerodynamic analysis to be exploited by TF. The numerical analysis tool for the thermal management is also exploitable opportunity for UPC:
At this point and with the exploitation opportunities of the project results finished, the partners are ready to analyse and validate the primary and secondary market potential, and structure a market penetration & development plan accordingly. Cooperation with regulatory bodies and third party sales and distribution licensees in the aeronautics markets can also used. This process has already begun through the concept development and pre-project market validation work carried out by the consortium within its existing customer bases. The final “Plan for the use and dissemination of the foreground” has been prepared in the last trimester of the project not including patent applications due to patents are not necessary, but with considering the use of the results considering:
• The knowledge in the field of aeronautics;
• Evaluation of possible industrial outcome for the research results obtained during this project;
• Estimation of the economic impact of the technologies and processes developed under the project;
• Observation of market trends and positioning of project results;
• Market analysis (actual market needs and size in Europe).

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