Cavity Formation and Associated Drag in a Supercavitating Flow Over Wedges in a Boundary Layer

Abstract

Supercavitating flow over wedges (half-wedges) attached to a solid boundary can be simulated by air injection in the wake of the wedges. Information on cavity formation behind single wedges in a boundary layer, specifically, cavity length, air demand, and pressure distribution inside and outside the cavity as a function of wedge characteristics (height and angle), stream velocity, and blockage effect was obtained by experiment. Drag on such single artificially supercavitating wedges was measured. Experiments were carried out in a conduit of rectangular cross section with the wedges attached to the bottom. The ultimate purpose of the investigation was to examine whether a cavity generated on a flat plate has a skin friction reducing effect and how such a cavity can be generated most efficiently by a wedge without introducing important supplementary drag.