Measurement of Pressure, Added Mass and Damping Coefficients for a Destroyer Model using the Marine Dynamic Test Facility

The Marine Dynamic Test Facility (MDTF) is a five degree-of-freedom forced oscillation test apparatus being purchased jointly by the Canadian Department of National Defence (DND) and the National Research Council of Canada (NRC). When completed, it will be installed in the towing tank of the Institute for Marine Dynamics (IMD) in St. John's, Newfoundland. The apparatus is designed to perform complex experiments with surface ships, submarines, underwater vehicles, etc. by putting them through pre-defined arbitrary trajectories, measuring the reaction forces and extracting the hydrodynamic characteristics of the vehicles from the measured data. There are also other novel applications which this apparatus could be put to. Currently IMD has a pilot version of the MDTF, with only dynamic heave and pitch, and variable yaw offset, capabilities. The pilot rig was used in a recent experiment to oscillate a destroyer model in pure heave and pure pitch modes in calm water. One purpose was to measure the added mass and damping coefficients. As well, the model was instrumented with 19 pressure transducers to measure the radiation pressure on the model hull as function of oscillation frequency, amplitude and forward speed. These data are vital for the proper validation of numerical codes, particularly since good experimental data on radiation load and pressure are relatively rare. This paper outlines the main features of the experimental technique, describes the data analysis procedures and presents results that show the validity of the approach. The huge amount of data gathered are still in the process of being analyzed and only some representative results are presented.