Forces on a body of revolution in a vortex flow field

Abstract

The development of mathematical models of marine vehicle manoeuvring has had a long history. To help quantify different and diverse theories a series of experiments have been proposed. The purpose of these experiments was to determine the out-of-plane forces on an underwater vehicle due to vortex shedding. This paper describes experiments conducted in a Circulating Water Channel to measure pressure and vorticity values at stations along a body of revolution. The-model was a 1 metre long body of revolution, diameter 0.125 metres with a detachable NACA 0020 appendage. A computer controlled transverse rig positioned a Freestone probe which was used to measure vorticity. A Scanivalve was used to acquire data at thirty-six pressure tappings at each station. Experiment runs were conducted under various conditions. All runs were with the body stationary, and the speed of flow maintained at 2.5 metres/second. The angle of yaw of the body was varied over a range from 0 degrees to 17.5 degrees both with and without an appendage. Appendage angles were varied from 0 degrees to 20 degrees whilst keeping the body at a constant yaw angle of zero degrees. Vorticity measurements were integrated to give circulation values for the vortices that were shed from the appendage and the body. Experiment results are compared with potential theory.