A test rig for the investigation of ship propeller/rudder interactions

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Description/Abstract

This report details the design and installation of a wind tunnel rig for the investigation of ship propeller and rudder interactions. The overall rig is designed for use in either of the two low-speed wind tunnels at the University of Southampton. The rig consists of two separate units which allow model ship rudders and propellers to be either tested independently or as a whole. The independence of the two units allows parametric studies to be made of rudder/propeller interactions while at the same time providing a facility for testing the freestream characteristics of both rudders and propellers.

The rudder rig incorporates a six-component strain gauge dynamometer to measure forces and moments. Both semi-balanced skeg and all-movable rudders can be tested. The rudder models are pressure tapped to give spanwise and chordwise pressure distributions.

The model propeller is driven from a 30 kW A.C. synchronous electric motor via a belt drive. The propeller support assembly is mounted to a tubular steel framework beneath the wind tunnel working section. The distance of the propeller axis of rotation from the wind-tunnel floor can be varied between 600 and 900mm. An in-line strain gauge dynamometer is used to measure the propeller torque and thrust. A variable-frequency electric motor-controller allows the propeller revolutions to be varied between 50 and 3000 RPM. The rig is designed to take a range of propellers with diameters between 700 and 1000mm. For the first application a four-bladed propeller with a diameter of 800mm was used.