Oscillating aerofoil and perpendicular vortex interaction

An experimental activity was conducted to investigate the aerodynamic effects of a stream-wise vortex impacting on a NACA 23012 oscillating aerofoil. The experimental setup allowed to study the effects of the blade pitching motion in the interaction with the vortex. The impacting vortex was statistically qualified by means of a three-dimensional hot-wire anemometry, taking into account also the vortex wandering phenomenon. The flow developed on the aerofoil was investigated through particle image velocimetry surveys carried out on different measurement planes along span-wise direction. The experimental study investigated both the light and the deep dynamic stall, representing typical helicopter flight conditions. In particular, in the tested light dynamic stall condition, the phase averaged velocity fields showed that in downstroke, the vortex impact triggers the flow separation on the aerofoil upper surface. Therefore, the vortex interaction can introduce detrimental effects on the blade performance. Moreover, the influence of the target aerofoil oscillating motion on the vortex trajectory was investigated.

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