CORDIS - Forschungsergebnisse der EU

Contribution to optimisation of heavy helicopter engine installation design

Final Report Summary - HEAVYCOPTER (Contribution to optimisation of heavy helicopter engine installation design)

Executive Summary:

The HEAVYcOPTer project is aimed at improving the engine integration of a heavy helicopter, namely the AW101, by using advanced numerical optimization methodologies. In particular, engine intake and exhaust systems were considered as components to be optimized. The intake performance was ameliorated by reducing the total pressure losses and the inlet flow distortion at the engine interface at two relevant flight conditions, i.e. hover and forward flight. Reduction in the backpressure was instead considered as the main goal of the exhaust optimization, together with a proper balance of hot and cold flows for guaranteeing appropriate cooling of the engine bay. In addition, some further aerodynamic characteristics of the engine installation, like for instance potential tailboom heating, potential re-ingestion of hot gases in ground idle conditions, and effect of rotor inflow in some representative flight conditions were taken into account. To this purpose, an in-house multi-objective evolutionary algorithm was used coupled with both commercial and open-source CFD solvers. The final results confirmed the achievements of substantial improvements in engine installation performance.

Project Context and Objectives:
The HEAVYcOPTer project is a Call for Proposal (CfP) in the framework of the CleanSky JTI, which in turn is the most ambitious aeronautical research program ever launched in Europe, essentially devoted to the identification and implementation of some breakthrough technologies aimed at improving the environmental friendliness of both fixed-wing and rotary-wing aircrafts, both in terms of noise emissions and fuel consumption.
In the Clean Sky (CS) framework, a dedicated section is devoted to rotorcraft (both helicopters and tilt-rotors), which is called Green RotorCraft (GRC). The GRC is organized in six tasks: specifically, GRC2 regards the design optimization and active flow control of both airframe and non-lifting dynamic systems for drag reduction.
The HEAVYcOPTer project refers to CS GRC2 and is aimed at implementing and applying an innovative design methodology to be used for efficient optimization targeted to engine installation improvement in a heavy helicopter, namely the AW101. To this purpose, an in-house multi-objective evolutionary algorithm coupled with commercial CFD solvers was used. In particular, effective aerodynamic design of intake and exhaust is essential for engine installation optimization and requires the accomplishment of multiple, and often conflicting, objectives in presence of multiple and multi-criteria constraints.
In the present case, the intake geometry was to be designed for maximum pressure recovery while minimizing the total pressure losses and flow distortions at Aerodynamic Interface Plane (AIP) with the engine. Several constraints were to be accounted for, i.e. the overall size and dimensions of the engine, minimum thickness issues related to construction, size and shape of the by-pass duct for particle separation, etc.
Regarding the exhaust, a shape optimization was carried out on the discharge duct with regard to its isentropic efficiency and swirl removal effectiveness by taking into account the dimensional constraints dictated by the engine exhaust. Moreover, an additional objective consisted in minimizing engine backpressure, since this is fundamental for maintaining the engine performance at the required optimum level. In addition, hot and cold fluxes were properly balanced with the aim of guaranteeing a sufficient engine bay cooling. Finally, prevention of tail boom heating, as well as avoidance of hot gas re-ingestion in sideward wind conditions were taken into account as functional constraints.

The objectives of the project were:
i) to set up a comprehensive and fully automatic optimal design tool, integrating the software suitable for engine installation analysis and an in-house multi-objective optimization algorithm already developed by the University of Padova;
ii) to apply such tool for the efficiency improvement of engine installation components based on the boundary conditions given by the manufacturer, in order to achieve a significant reduction in the engine installation losses.

The above mentioned objectives were achieved by means of a dedicated programming and simulation activity, where the software tools available at the leading industry premises for the design and analysis of engine installation performance will be interfaced together and with the optimization tool proposed by the UNIPD-HIT09-MDA Consortium. The result was a robust procedure where only the initial geometry importation and parameterization were carried out off-line, while meshing, geometrical/grid manipulation, as well as CFD analyses will form an automatic loop. The optimization tool, which is capable of efficiently handling complex multi-objective problems, was applied to review the basic intake and exhaust design, with the aim of minimizing any detrimental effects on both drag and engine installation, through both a reliable intake and exhaust shaping and an analysis and control of flow distortion, total pressure losses and flow separation. Finally, the optimized engine installation geometry was checked for compliance with feasibility constraints in order to accomplish industrial needs for prototyping and testing.

Project Results:
See Attached pdf document.

Potential Impact:
The HEAVYcOPTer project is expected to result in a series of environmental benefits: in fact, a better engine installation will ultimately lead to an increase in the engine global efficiency and hence in reducing fuel consumption for the required levels of thrust. On the other hand, if a global reduction in the required thrust level is to be achieved as a result of the overall GRC project – by virtue of a possible aircraft drag reduction - the HEAVYcOPTer project will result in even more evident fuel savings. Actual quantification of benefits in terms of fuel saving has not yet been carried out being out of the scope of the project but it will be estimated within GRC2. In addition, the final optimized components will be tested either in wind tunnel or in flight in the framework of GRC2, in order to verify the predicted margins of improvement.
The expected impacts can be seen as twofold: the first is product-specific, therefore "technical" and the second is more general and we shall refer to it as “social". In fact, both can have a deeper influence on the European competitiveness.
From the technical point of view, the development of a multi-objective optimization platform will have a positive impact on the reduction of the time-to-market for helicopter and aircraft industries, which will be able to develop aircraft components faster, better and cheaper, as per a reduction in the wind tunnel costs which will decrease the industrial development costs. Moreover, when optimized components will be implemented and industrialized, this will lead to more efficient vehicles having a reduced drag, which will have also a positive impact on the fuel consumption, an aspect which can be seen in direct connection to the "eco-design" concept. Referring to helicopter, a step toward a wider diffusion of such kind of aircrafts is foreseen with the help of the present work. Actually, the development of more efficient and affordable helicopters is seen as one of the strategic plans for a decongestion in the air traffic.
All the participants in the Green Rotorcraft Consortium will benefit from HEAVYcOPTer, as the compiled version of the optimization toolbox will be available to each partner. The generality of the approach implemented will make it possible for aircraft industries to use the toolbox according to the specific objective functions of interest. In fact, the provision of best optimization approaches directly strengthens the competitiveness of the European aircraft industry, which is in alignment with the objectives of THEME 7 "Transportation" of the FP7.
Regarding the "social" impact, a much wider view is envisaged. The alignment of the proposal objectives is directly in accordance with “greener” pan-European transport systems for the benefit of all citizens and society and climate policy, which are declared as main drivers of the THEME 7 according to the actual work program.
Moreover, a social impact in terms of improved knowledge is expected: specifically, due to the academic nature of one of the participants, one major dissemination opportunity was given by publications. In particular, a series of scientific and promotional papers, web sites, seminars and University lessons have been carried out during the project and will be implemented after the project closure as well. The HEAVYcOPTer project has potential innovation impacts on the actual state of the art: both scientific journals and international conferences have been used to explain the novelties and the wide applicability of the proposed research, even in a non-aeronautical field. At the same time, this publication activity, especially conferences, has been a way of exploitation, in that other helicopter or fixed-wing aircraft manufacturers could take advantage of the adopted approach and use it directly or derive analogous methodologies.
Moreover, the project achievements and knowledge have been transferred to the education of the new generation of aerospace engineers. This has enabled students to actively participate in upstream research activities and has given them the opportunity to perform applied research in cooperation with the elite of the European aeronautics industry. In addition, this has had a positive impact on recruitment of young PhD students and researchers involved in the development of advanced design methodologies for more efficient helicopter and aerial vehicles. Finally, a special effort has been made to support young scientists and engineers for their training and in order to attract their interest in the topic and in flight physics in general, by holding workshops with external scientists and students.
The dissemination strategy has been intended to optimize dissemination of project knowledge to organizations that may be interested in the technological results and in the further development and/or applications of the main project achievements. To this purpose, favorable conditions will be created to facilitate exploitation even after the end of project. Specifically, with the project completion, the following main outputs are made available for further exploitation:
- Best practice approach for reliable helicopter engine installation simulations using advanced numerical high-fidelity tools;
- Advanced high-fidelity, multi-objective optimization procedures for enhancing helicopter efficiency;
- Fundamental knowledge on the design process of the engine installation system components;
- Final assessment of the overall engine installation performance.
As already mentioned, one of the proposal main strengths was that the whole optimization chain was released to the GRC Consortium at the end of the Project, following the typical rules of open source software, thus allowing end-users to access and exploit the developed tool in their research or work for free. This approach ensures that the beneficiary of the EC funding will not be limited solely to the leading industry, but the whole GRC Consortium will be able to exploit its achievements.
The delivered optimization chain includes the optimization platform in a compiled version, i.e. the GDEA optimizer, all the interfaces with Hypermesh®, TGrid® and Fluent®, along with the pertinent theoretical and user’s guides as well as a tutorial on how to use it.
Since the Topic is targeted at improving efficiency of aircraft components, the user groups of the results may consist mainly of the industrial companies and research institutions of this sector. Through the final assessment phase of the project, an effective design process and the potential of multi-objective aerodynamic optimization can be exploited by GRC Consortium partners. This ensures the dissemination and exploitation of the achievements to the European aircraft industry and research community.

List of Websites:
Participating members
HIT09 S.r.l. IT
MDA S.r.l. IT

Coordinator contact details:
Ernesto Benini
Via Venezia, no.1
35131 Padova, Italy
+39 (0)49 8276767

Technical Leader contact details:
Rita Ponza
Galleria Storione, no.8
35100 Padova, Italy
+39 (0)333 2900558