An Improved Tip Vortex Cavitation Model for Propeller-Rudder Interaction

The paper starts with the computational modelling of the tip vortex cavitation in uniform flow conditions with an isolated propeller in detail and provides experimental validation. It then moves onto further modelling to include the effect of non-uniform flow and the presence of a rudder placed in the propeller slipstream. The propeller-rudder arrangement of the Newcastle University research vessel, The Princess Royal, and associated experimental data were used for Experimental Fluid Dynamics (EFD) analysis to validate the modelling. The cavitation simulations were conducted using commercial CFD software, Star CCM+. A new meshing technique, which utilizes a Mesh Adaptive Refinement approach for Cavitation Simulations (MARCS), recently developed by the authors, has been applied successfully to simulate the tip vortex cavitation, particularly to trace its extension up to the rudder in the propeller slipstream. The comparison of the CFD and EFD methods for the isolated propeller in cavitation tunnel conditions showed very good agreement in terms of the thrust and torque coefficients of the propeller as well as the sheet and tip vortex cavitation patterns observed. The cavitation simulations have been extended for the same propeller by using the new mesh refinement approach to include the effect of the hull wake and the presence of the rudder. Although the latter simulations fall short of the EFD results and hence they are still under development, the paper presents the developments and results so far to achieve the ultimate aim of this study, i.e. computational modelling of cavitating tip vortices of a propeller interacting with a rudder.