Trailing edge flap flow control for dynamic stall

Results of a series of dynamic stall tests in a wind tunnel of an aerofoil fitted with a pitching, trailing edge flap are presented. Phase angle, amplitude, motion profile and duration of the flap wereinvestigated to assess the potential of the flap of mitigating the adverse effects of dynamic stall. The tests were a continuation of the investigations by Feszty et al. (2004) using a computational fluid dynamics method, and the results broadly confirm their conclusions. The results presented in this paper also confirm the observations from experimental work Gerontakos and Lee (2006) and Lee and Gerrontakos (2007) at lower Reynolds number in dynamic stall by strong suction being generated over the aerofoil lower surface, and it is the modification to the lower surface shape by the flap that creates this effect. The dynamic stall vortex acts to enhance the lower surface suction, and careful flap phasing and flap motion profile shaping can make the control more effective