Reynolds-Number Scaling Effects on the EUROPEAN High Lift Configurations

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 mil. up to deep cryogenic conditions with Re = 25 mil.. 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 mil.. In the intermediate range, 5 mil. < Re < 15 mil, a highly nonlinear behavior of the maximum-lift values is observed, which requires further investigation