Investigation on RANS prediction of propeller induced pressure pulses and sheet-tip cavitation interactions in behind hull condition

Abstract

This paper investigates the numerical prediction of cavitation and hull pressure pulses induced by a marine propeller operating in behind-hull conditions of a container vessel in model scale. Simulations are performed using commercial package Star-CCM+ and opensource package OpenFOAM using RANS approach and predictions are compared with experimental measurements. A mesh dependency study with respect to wake prediction is also presented. Operating conditions scaled to two different Reynolds numbers with the same propulsion characteristics and cavitation number are considered to study scaling effect. Simulations using tip refined mesh are performed and compared with using base mesh to study the tip vortex generation, tip vortex cavitation, its interaction with sheet cavity and induced pressure pulses. The influence of time step length is also investigated.Star-CCM+ and OpenFOAM predict consistent results. The predicted cavitation patterns agree well compared to experimental measurements as well as pressure pulse levels up to 3~4 times blade passing frequency (BPF) especially for the predictions with tip refined mesh. The sheet cavitation is the major contribution to 1st and 2nd order BPF pressure pulses and its closure has significant contributions to higher-order pressure pulses. Deduced pressure pulses by tip vortex cavitation (TVC) are significant ranging from 3rd order to 10th order of BPFs. The TVC induced pressure pulses are related to its violent bursting behavior which is influenced by the closure of the sheet cavity.