Experimental investigation into the impact of slipstream wash of a podded propulsor on the marine environment

Abstract

The paper presents the results of an experimental investigation into the velocity field of a podded propulsor carried out by laser Doppler anemometry and the use of this information for assessing the potential impact of a podded propulsor slipstream, in terms of wash velocity, on the marine environment. The investigation was carried out in the Emerson cavitation tunnel of Newcastle University with the roll-on roll-off passenger ship or ferry (ROPAX) hull model as part of the project entitled ‘optimal design and implementation of azimuthing pods for the safe and efficient propulsion of ships’ sponsored by the EU Fifth Framework Programme initiative. Comprehensive velocity field measurements were made in open water, behind the simulated wake of the ROPAX hull and in the bollard pull condition. The mean velocity distributions in the axial and radial directions were calculated from the measured velocity fields to evaluate the potential impact of the slipstream wash of a podded propulsor on the environment. For comparison purposes, some results from similar measurements made with a conventional shafted propeller are also included. The experimental results have revealed that the most significant impact of the propeller slipstream wash on the environment could occur when a ship departs from a port.

Keywords

wash velocity podded propulsor environment laser Doppler anemometry

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