Study on Unsteady Cavitating Flow Simulation around Marine Propeller using a RANS CFD code

Reduction of greenhouse gas (CO2 etc) emission is an important issue to address global warming. In recent ship design, it is essential to improve propulsive performance and fuel oil consumption, and the demand for high-efficiency propeller is growing rapidly. The authors have been investigating the possibility of the application of CFD to the propeller performance evaluation and optimization. In these previous papers[1,2], the authors presented CFD simulation of non-cavitating and cavitating flow around a marine propeller using a commercial CFD code. A good agreement with the experiment was confirmed for the non-cavitating flow. Various validations were also carried out for the cavitating flow, and the followings were described. First, we confirmed that the cavity shape in a uniform flow was qualitatively well estimated, but the difference between two propellers, of which the blade sections were somewhat different, were not reproduced. Secondary, the cavity shape in the non-uniform flow was also qualitatively well estimated, but the resulting pressure fluctuation was not validated. In this paper, the systematic experiment was carried out using two marine propellers, which dimensions were very similar, to study the above issues, and simulation was carried out for the same cases. In the uniform cavitating flow simulation, the difference of cavity shape around these propellers was reproduced, and the quantitative validation of the fluid force such as thrust and torque was done. In the nonuniform cavitating flow simulation, the comparison of the cavity shape with the experiment and the quantitative validation of the fluctuating pressure on the wall of the cavitation tunnel were done.