Flow visualization studies of the Mach number effects on the dynamic stall of an oscillating airfoil

Compressibility effects on dynamic stall of a NACA 0012 airfoil undergoing sinusoidal oscillatory motion were studied using a stroboscopic schlieren system. Schlieren pictures and some quantitative data derived from the are presented and show the influence of freestream Mach number and reduced frequency on the dynamic stall vortex