The Structure of a Three Dimensional Tip Vortex at High Reynolds Numbers

The tip vortex structure of a three dimensional hydrofoil at high Reynolds number was measured experimentally in both the 48-in (1.22- m) diameter water tunnel and the 48-in (1.22-m) wind tunnel at the Applied Research Laboratory, Penn State. The flow on and near the hydrofoil was measured using a number of flow visualization techniques, laser velocimetry (tip boundary layers) and pressure taps. The downstream tip vortex was measured with a three-component laser velocimeter at a number of streamwise positions with a detailed planar mapping of the flow in the region of cavitation inception. The effect of Reynolds number and applied tip roughness on the downstream tip vortex was investigated. In addition, the importance of the unsteady pressure fluctuations in the core on cavitation inception is discussed.