Within the European High-Lift projects I and II, extensive experimental and numerical investigations on the aerodynamics of high-lift configurations have been carried out. The studies are conducted using the KH3Y windtunnel model DLR F11, which is representative of a wide-body commercial aircraft. A step-by-step complexity increase up to a complete high-lift configuration, including pylon, nacelle, and nacelle strake, is carried out to identify and separate the lift and drag behavior for the components of the high-lift system and their Reynolds number dependency. The wind-tunnel data have been gathered in the European Transonic Wind Tunnel in Cologne in three different test campaigns. To include the complete analysis of the stall behavior for the different configurations of a complex three-dimensional tapered high-lift wing with nacelles extends the scope of a single paper. Therefore, the focus of the present contribution is laid on the detailed analysis of Reynolds number scaling effects with respect to lift curves and drag polars. The combined variation of the dynamic pressure and the total temperature in the European Transonic Wind Tunnel allows covering a Reynolds number range from Re 1:5 10 6 up to deep cryogenic conditions with Re 25 10 6. The final comparison of the four configurations reveals that the sequence of maximum lift values is maintained for the lowest and highest Reynolds number, although the increments between the configurations differ. The strongest increase in maximum lift is observed up to Re 5 10 6. In the intermediate range, 5 10 6 < Re < 15 10 6 , a highly nonlinear behavior of the maximum-lift values is observed, which requires further investigation.
The European Transonic Windtunnel (ETW) is a pressurised cryogenic facility suitable to achieve flight conditions for cruise and high lift configurations of aircraft models. Becoming involved in the design process of new aircrafts or providing high quality data for the validation of CFD codes requires the availability of qualified measurement techniques for flow field analysis and model surface diagnostics. Over the past decade ETW has developed special instrumentation and installations, together with optical methods for flow visualization or model deformation measurements in order to fulfil the requirements of high Reynolds number aerodynamic testing. This paper gives an overview on the relevant optical tools operated under severe test conditions and presents new techniques under development. Gained experiences are addressed and achievements and maturity are documented.
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