Computation of hull-pressure fluctuations due to non-cavitating propellers

This paper describes a new coupling procedure of two boundary element methods aimed at computing propellerinduced hull-pressure fluctuations. The first method computes the incompressible potential flow of a propeller operating in a ship wake field. The second method computes the propeller-radiated pressures by replacing the incompressible-flow solution on the rotating propeller blades by a set of rings of stationary sources. This source system is used as input in an acoustic scattering analysis of the wetted ship hull and undisturbed free surface based on the Kirchhoff-Helmholtz integral equation. Thus, hull pressures are obtained in the frequency domain on the basis of a time-domain source description.
Computed hull pressures for non-cavitating conditions are presented for a container vessel that was successively fitted with two different propellers, one being a six-bladed propeller designed for the vessel, the other a two-bladed propeller. Comparisons are made with scale-model tests performed in a towing tank. For the two-bladed propeller, the computed results are in good agreement with the experimental results. The six-bladed propeller shows somewhat larger variations in correlation.