Advanced measurements of rim-driven tunnel thrusters --The Wageningen TT-series JIP--
Tunnel thrusters generate a side force on the hull of a ship to enable maneuvering, mooring, crabbing and/or dynamic positioning. In addition to conventional thrusters with a shaft and gearbox, propellers with blades fitted to and driven by electro-magnetic forces applied at the rim of the thruster tunnel (so-called rim-driven propellers) can be applied. However, for rim-driven tunnel thrusters limited or no systematic data on side force performance is available, and no cavitation behavior, pressure fluctuations, noise and vibrations has ever been observed or measured in a systematic way. The objective of the Joint Industry Project (JIP) on the Wageningen Tunnel Thruster series (TT-series) is to design a tunnel thruster propeller series of both conventional and rim driven types with reduced noise and vibration excitation, without compromising side force performance. This paper focuses on instrumentation and measurement techniques used in the test campaign with rim-drive tunnel thrusters, with special emphasis on the noise measurements.This test campaign was carried out in the scope of the exploration phase of the project. In this phase several ideas for propeller design improvements were tested, as well as the performance of the measurement systems.