Experimental study of drag-reduction devices on a flatback airfoil

Various trailing-edge drag-reduction devices, including a new flap device, were examined experimentally on a flatback airfoil in a wind tunnel. The tests concerned a 30% thick airfoil with 10.6% thick trailing edge. Pressure, hot wire, and stereo particle image velocimetry measurements were performed at a chord Reynolds number of 1.5e6. Results show that the best-performing devices decrease drag, increase the vortex shedding frequency, and reduce flow variation downstream of the wing trailing edge. The best-performing device was a combination of the flap with an offset cavity plate. Further investigation is required for the optimization of the new device to examine its effects on noise reduction, load mitigation, and control