3-D LDV Mapping of the Flow About a Waterjet-Powered Hull in a Tow Tank

Abstract

A three-velocity-component Laser Doppler Velocimetry (LDV) system has been developed at the David Taylor Model Basin (DTMB) for use in obtaining the flow field around tow-tank surface ship models. The system configuration and operation is described and a detailed analysis of the uncertainty associated with the system measurements is presented. Results of measurements on a waterjet-powered destroyer hull are presented. On this hull, velocity fields are shown ahead of the inlet, inside the inlet, and at the exit of the jet. Pitot tube measurements are combined with the velocity measurements at the propulsor exit to obtain the static pressure field. It is shown how these measurements are used to obtain mass-flow and flow distortion coefficients so that the pro­pulsive performance may be evaluated.