Experimental Investigation of Perpendicular Vortex Interaction by Stereo Particle Image Velocimetry

The aerodynamic effect of a stream-wise vortex impacting on an oscillating airfoil was experimentally studied in the present work by means of a stereo particle image velocimetry. The experimental rig had enabled the study of the aerodynamic effects induced by the vortex during the blade pitching motion. In particular, the resultant effect of the impacting vortex and airfoil oscillation was highlighted comparing a light dynamic stall regime with equivalent steady conditions. A stereoscopic particle image velocimetry technique was applied to a measurement volume close to the airfoil upper surface. The analysis and comparison of the different test cases allows to prove that, under certain conditions, the vortex impact could trigger the stall of the local blade section, indicating that detrimental effects on the blade performance can be introduced by perpendicular vortex interactions.