Experimental and numerical investigation on delta-wing post-stall flow control

Abstract

The flow around delta wings is dominated by a leading-edge vortex system, which induces increased near wall velocities above the wing hence producing high suction peaks. These are responsible for the lift needed at high angle of attack aircraft maneuvering. In the flight regime beyond stall the flow separating from the leading-edge encounters a very steep adverse pressure gradient and consequently doesn’t roll up into a vortex-like structure. Rather, encloses a massive dead-water region over the entire wing. With unsteady jet blowing at the leading edge additional momentum is created leading to a reattachment of the flow at the wing surface thus increasing the lift significantly. The investigated flow control method can be applied for extending the flight envelope, enhancing maneuvering capability and flight stability. This flow manipulation technique is investigated on a generic half wing model at a very high angle of attack (α = 45°). The investigations comprise wind tunnel testing, using force measurements and stereoscopic particle image velocimetry, and complementary scale resolving numerical simulations, for a detailed analysis of the unsteady phenomena.