Flow Visualization of Wakes of Airfoils having Blunt Trailing Edge in a Shock Tube

Abstract

The vortex shedding and near wake flows of blunt trailing edge NACA 0012 airfoils and flat plates having rectangular trailing edge cavities are observed in Mach 0.6 Shock tube flow with a Schlieren system.
While the sharp trailing edge generates only one discrete vortex, strong many discrete vortices are generated from blunt trairing edges. On the other hand dull and weak vortices can be seemed for the segmented blunt trailing edge.Circular cylindrical waves are formed due to the generation of discrete vortices.
For blunt trailing edge airfoils with angle of attack vortices are shedded from the portion near the lower corner of the trailing edge, and their mean rear stagnation points seem to be near here.It can be thought that this is a reason why blunt trailing edge airfoils have higher lift.