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Design, Simulation and Flight Reynolds-Number Testing for Advanced High-Lift Solutions

Tags: Air

State of the Art - Background

Laminar wings offer a significant potential for advancing aerodynamic performance and thus improving the environmental acceptance of future aircraft. While offering a large fuel saving potential, laminar wings for large transport aircraft still suffer from incompatible high-lift leading edge systems. Natural laminar flow (NLF) technology poses new design constraints and adds further design parameters to the design space. Hence, the design space of a NLF high-lift system must be wider compared to the design space of a high-lift system for a transport aircraft with turbulent wings. Exploring a wider design space calls for automated optimisation algorithms for which, however, code developers often lack the specific knowledge.

In the industrial design process of high-lift systems, the wind tunnels play a very important role as they allow a reliable analysis of the design variations with respect to aircraft performance. Pressurised cryogenic wind tunnels are able to simulate almost any flight condition so these tunnels are very important in minimising the uncertainties. An improvement in the testing efficiency, by applying simultaneously different state-of-the-art measurement techniques under cryogenic conditions, provides the potential to decrease the development costs within the industrial design process.


DeSiReH supports the realisation of Vision 2020 by improving the aerodynamics of the high-lift system. This will be achieved by considering the numerical design methodology and the measurement techniques for cryogenic conditions for an advanced laminar high-lift wing design to be performed in DeSiReH. This will facilitate an improved industrial design process in terms of product quality, efficiency and reduced development costs with respect to the high-lift systems.

DeSiReH addresses the following quantified objectives:

- reducing the industrial aircraft development costs by 5% through less and more efficient wind tunnel testing;

- decreasing the time-to-market by 4% by improving the aerodynamic design turn-around time;

- improving the industrial high-lift design process efficiency by 15%;

- designing a compatible high-lift system enabling the NLF-potential of reducing aircraft drag by 5%.

Description of Work

Existing and validated high-fidelity numerical tools will be developed for an efficient high-lift design and optimisation process chain, which is able to explore the design space of a typical multi-objective optimisation problem.

These strategies and tools are applied to the aerodynamic design of a high-lift system for the NLF wing. The key objective of the design activity is to achieve the required high-lift performance in take-off and landing whilst facing the constraint to maintain NLF at cruise to the best possible extent. The matured methods are benchmarked against the aerodynamic high-lift design by applying today's industrial design approach. This benchmark is an important activity for the targeted qualification of the high-fidelity optimisation process and strategies for industrial implementation.

A further important work package focuses on the improvement of the experimental measurement technique for cryogenic testing. The objectives here are to enhance the measurement accuracy of the results and to generate the capability to apply different important techniques (e.g. transition measurement and deformation measurement) in parallel, and to analyse the influence of the model surface quality on the high-lift performance. These techniques are finally applied in the ETW at high Reynolds numbers on the HARLS model equipped with the high-lift system.

Expected Results

DeSiReH intends to provide an efficient, high-fidelity numerical design process which will be applied for designing and testing a high-lift design system for a laminar-flow wing. The design will be tested in the ETW in a close joint action between the numerical and experimental specialists. The latter will use the enhanced testing strategies and technologies also prepared in DeSiReH. The results will be ready and available for being integrated into the Smart Fixed-wing Aircraft part of the Joint Technology Initiative 'Clean Sky'. The results will also be promoted by an intensive dissemination within respective papers and workshops, for instance in the KATnet II Coordinating Action.

The results include, but are not limited to:

- an optimised laminar wing high-lift system;

- an improved high-lift design methodology in an industrial context and evaluation of the aerodynamic high-lift system solutions;

- advanced experimental measurement techniques at cryogenic conditions;

- quantification of the environmental and economical benefit in relation to the ACARE targets.

DeSIRell 2009-2012