Investigation of cavitation influence on propeller-rudder-hull interaction

Student thesis: Doctoral Thesis

Abstract

Computational modelling of tip vortex cavitation of a ship propeller has its challenges particularly to extend the cavitating tip vortex trajectories in the propeller's slipstream for investigating their influence on the propeller-rudder-hull interaction. Although the prediction of sheet cavitation on the propeller blade surfaces has been tackled successfully by many researchers, the research to extend the prediction model for the tip vortex cavitation from all propeller blades simultaneously and throughout the rudder is rather scarce. This PhD study, therefore, aims to contribute in this area of research to investigate the cavitation influence on propeller-rudder-hull interaction, especially due to the tip vortex cavitation, by using a commercial Computational Fluid Dynamics (CFD) code.To achieve the above aim, an investigation on the propeller-rudder-hull system is conducted in steps; first by modelling the propeller performance and cavitation in CFD for the isolated propeller case, and next to continue with the propeller-rudder system and finally by modelling the propeller-rudder-hull combination case to represent the ship system. The CFD modelling for these cases are conducted using the commercial CFD software STAR-CCM+ and validated by the available Experimental Fluid Dynamics (EFD) data for three benchmark propellers including the Potsdam Propeller Test Case (PPTC) VP1304, INSEAN E779A model propeller and The Princess Royal research vessel model propeller which are all tested in different experimental facilities.The cavitation model used in the commercial software is the Schnerr-Sauer model based on the Rayleigh-Plesset equation. This model together with the new meshing technique called MARCS, which is developed by the Author as an advanced Mesh Adaption Refinement procedure for Cavitation Simulations, is applied successfully to simulate the cavitating tip vortices from all blades simultaneously in the propeller's slipstream beside other cavitation types. The cavitation simulations are conducted to test and validate the MARCS procedure to include the presence of the rudder and to study the interaction between the propeller and rudder including the effect of the hull wake in the model scale.The simulation results are validated for two different types of propeller-rudder arrangements involving a typical container ship propeller-rudder arrangement and The Princess Royal propeller-rudder arrangement with an inclined shaft and flat rudder section tested in the Emerson Cavitation Tunnel.Further cavitation simulations with the commercial code using the MARCS procedure are also conducted for the scaled full-model of The Princess Royal research vessel to simulate the model tests conducted in the depressurised large circulating water channel of CNR-INSEAN and to validate the simulation results with the EFD measurements available from this facility. Finally, the same computational tool and procedure are used for the cavitation simulations of The Princess Royal in full-scale, and the simulation results are compared with the cavitation observation images available from sea-trials with this vessel.In spite of various shortcomings, which can be further improved, implementation of the new meshing procedure developed has proven that using a state-of-the-art commercial CFD code can be a practical and attractive analysis tool to investigate the influence of cavitation on propeller-rudder-hull interaction in the model and full-scale with confidence. Furthermore, it is feasible, and may be more attractive, to simulate the propeller cavitation directly in full-scale in order to save the additional time, effort and expense required for model tests. Due respect is given to the invaluable contributions made by the EFD in the validation stage of the CFD methods.
Date of Award1 Oct 2018
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorMehmet Atlar (Supervisor) & Erkan Oterkus (Supervisor)

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