Numerical and Experimental Investigation on Dynamic Stall Vortex

The flow physics of dynamic stall vortex on a thin airfoil is probed by wind tunnel testing and computational analysis. The two-dimensional wind tunnel testing with unsteady pressure measurement reveals the creation and development of the leading edge and the trailing edge dynamic vortices. Also conducted in the test is the smoke wire technique together with the high speed video recording, which visualizes the detailed spatial and timewise mechanism of the dynamic vortices. The key feature of the leading edge vortex is that the airfoil pitching motion creates strong suction field near the leading edge to supply rotational energy to the leading edge vortex before it eventually convects downstream. The similar process is observed for the trailing edge vortex in downstroke motion. The numerical simulation with the discrete vortex method displays the vortex motion consistent with the experimental visualization, and the calculated streamline well correlates with the test result.