Experimental investigation of Mach- and Reynolds-number dependencies of the stall behavior of 2-element and 3-element high-lift wing sections

Experimental investigations have been carried out with the two-dimensional DLR-F15 high-lift wing section model in DNW-KKK cryogenic wind tunnel in order to differentiate between the influence of Mach- and Reynolds number on the stall behavior. Due to the cryogenic environment Mach- and Reynolds number have been varied independently between M = 0.1 - 0.25 and Re = 1.4 x 106 - 15.6 x 106. The investigation covers 2-element and 3-element configurations at various slat and flap settings and two different slat shapes. Focus of the investigation is to identify conditions of turbulent leading edge stall, shock related lift limitations and flap separations and their influence on achievable maximum lift coefficient