Numerical Investigation of Dynamic Stall Control by a Nose-Drooping Device

摘要

Various technologies have been proposed recently to influence the flow on a helicopter rotor blade during dynamic stall:rnlocal suction/blowing on the airfoil upper surface utilizing the synthetic jet concept, leading edge flaps (slats) to completelyrnavoid separation, dynamic deformation of the airfoil section (active camber), deformation of a small part of thernairfoil leading edge (dynamically deforming leading edge, DDLE-concept) and dynamically drooping of the airfoil leadingrnedge (Nose-Drooping concept). The latter has been investigated numerically and found to be very efficient with respectrnto favorably control dynamic stall. In contrast to other procedures the Nose-Drooping concept has the advantage tornbe applicable on the rotating blade, i.e. the droop is only active when necessary, i.e. on parts of the retreating side. On thernadvancing side the airfoil has its original shape which may be designed to be shock free within the design point.rnPresent numerical results show the efficiency of the Nose-Droop concept with respect to dynamic stall control.rnExperimental investigations on blade sections with actively drooping the leading edge are in preparation.