Numerical Investigation of Perpendicular Blade-Vortex-Interaction on a Pitching Airfoil in Light Dynamic Stall

Computational Fluid Dynamics was used to investigate the effects of perpendicular blade vortex interactions on the aerodynamic performance of an oscillating airfoil. In particular, the test case studied was a stream-wise vortex impacting on the leading edge of a NACA 23012 airfoil oscillating in light dynamic stall regime, representing a typical condition of the retreating blade of a helicopter in forward flight. The results of time-accurate simulations were validated by comparison with particle image velocimetry surveys. The analysis of the numerical results enabled to achieve a detailed insight about the overall effects on the interacting flow field and on aerodynamic loads acting on the oscillating airfoil due to the vortex interaction. Indeed, the comparison with the clean airfoil case shows a severe loss of performance produced by vortex interaction during downstroke motion of the airfoil, as the vortex impact triggers the local stall of the blade section.