The twin screw diesel powered propulsion train of a 5,000 ton vessel has been discretized as a combined lumped parameter and continuous mass mechanical system comprising 73 distinct sections. The axial and torsional vibratory responses have been determined from the receptance characteristics of the complete rotor/bearing/propeller system, and the coupling of the torsional and axial modes introduced by the propeller action has been investigated via perturbation methods. The spatial distribution of pressure pulsations at the propeller plane was subsequently employed to estimate the radiated sound power field treating the propeller as a rigid piston constituting an assemblage of monopole sources. The results obtained by the model show encouraging agreement with available underwater acoustic measurements at the frequencies of interest.
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