Mixed-Flow Waterjet (MxWJ) Model 5662-1: Initial Study of Yaw Effects on Waterjet Powering and Transom Depth Effects on Waterjet Priming

This report is a partial documentation a series of model-scale experiments conducted 5/07-6/07, on Mixed-Flow Waterjet (MxwJ) Model 5662-1, a waterjet propelled variant of the Joint High Speed Sealift (JHSS) hull platform. This document contains data and evaluations from initial investigations into the following two waterjet topic areas: (1) The effects of model yaw angles on waterjet powering. Model-scale rotor force measurements of thrust and torque at angles of yaw up to 3 degrees showed little variation compared to the equivalent forces measured at zero yaw angle. Model drag and side forces, as expected, showed substantial increases as yaw angle was increased. (2) The effects of variations in model transom depth, and by extension the submergence of the waterjet pump inlet, on the priming of the waterjets. Visual observations as to the state of fluid flow through the waterjets indicated that the initial waterjet design criterion of retaining 50% of the rotor submerged was conservative, and could be relaxed somewhat for future designs.