Numerical investigation on propeller cavitation performance with erosion risk under ship hull wake and oblique flow condition

In this work, the cavitation erosion risks of PC456 propeller blades surface in a ship-propeller-rudder system under different cavitation numbers are explored. SST k-ω turbulence model and Schnerr-Sauer cavitation model are adopted for the hydrodynamic and cavitation performance simulations of the propeller in the hull wake and oblique flow. Meanwhile, the sliding mesh model is used to simulate the propeller rotation motion. Firstly, the calculation reliability of hydrodynamic performance and cavitation performance is analysed, and the predicted unsteady cavitation patterns are basically consistent with the experimental results. Based on the verified calculation model, the propeller cavitation performance with its erosion risks in the ship-propeller-rudder system is predicted. The results show that under open-water conditions, the propeller cavitation of each blade is basically the same due to the uniform inflow. Compared with the open-water propeller, this time-varying cavitation produces a large number of pressure fluctuations at the cavity collapse. The unstable cavitation increases the erosion risk of the blade area covered by cavitation. The cavitation erosion risk is inversely related to the cavitation coverage area. Then, the flow direction is changed to ±20°, and the impact of the oblique flow on propeller cavitation erosion risks is observed. The results indicate that the sheet cavitation has an erosion effect on the propeller at where the cavitation collapses. When the propeller works in the stern wake and oblique flow, the inlet flow becomes uneven and the cavitation changes periodically, which will gradually increase the propeller cavitation erosion risk. This research work has a certain reference significance for the propeller cavitation control and erosion protection.