Far field wake velocity measurements with hot film probes

Abstract

An investigation into the feasibility of measuring wake velocity profiles in a towing tank using hot film probes has been conducted. Results show that such a system is feasible, but care must be taken to minimize calibration errors due to the small velocity differences being measured. Included are calibration data and plots of wake profiles behind a sphere measured at the U.S. Naval Academy's Hydromechanics Laboratory and the MIT Ship Model Towing Tank. These plots show the effect of the presence of a free surface on the development of turbulent wake. Data collected using the hot film system can be used as an input to analytic wake algorithms, compared to wake prediction or visualization techniques