Effect of the trailing edge flap on dynamic stall performance of helicopter rotor airfoil

Impact of the trailing edge flap parameters on the characteristics of dynamic stall is investigated for the smart rotor. The model is established for the dynamic stall of the rotor blade with the trailing edge flap. The overhang and the gap between the trailing edge flap and the blade are considered. Through the method of computational fluid dynamics (CFD), the effects of the gap size and the location of flap hinge have been studied, and the effect of flap deflection, flap duration, and flap start time has also been calculated. The result shows that the flap control can effectively improve the flow condition under dynamic stall conditions and delay dynamic stall. The optimization design of the flap actuation is that the amplitude of flap deflection is designated to 25°, whereas the flap duration azimuth angle is chosen from 240° to 360°. There are overhang and gap between the trailing edge flap and rotor blade. It is indicated that the overhang reduces the control effect of trailing edge flap. The gap also affects the control effect, but its length (≤2%) has little effect on the result.