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 in both facilities using a number of flow visualization techniques and laser velocimetry. The downstream tip vortex was measured with a three-component laser velocimeter at a number of streamwise positions. A detailed planar mapping of the flow in the water tunnel was completed near the region of cavitation inception. The effect of roughness on the downstream tip vortex was investigated. In this paper, these measurements are presented with discussion relative to the occurrence of cavitation.