Observations on the Development of a Tip Vortex on a Rectangular Hydrofoil

Abstract

The present paper describes a flow visualization study that focuses the development of a tip vortex on a rectangular NACA-66 hydrofoil. The experiments have been performed in a towing tank. Illumination with a thin laser sheet together with distribution of dye have been utilized as a means of observation. The results demonstrate the growth of the vortex along the chord, the increase in its dimensions with increasing incidence angle and decreasing Reynolds number. They also show that the center of the vortex moves inward towards the root with increasing incidence angle, increasing chordwise location, and decreasing velocity. Empirical relations for these trends have been computed. The observations also demonstrate that the flow around the tip is dominated by muliple vortex structures that include the primary vortex, a counter rotating structure, shear layer eddies, and several other secondary vortices.