9 th International Conference on Hydrodynamics October 11-15, 2010 Shanghai, China 705 2010, 22(5), supplement :747-752 DOI: 10.1016/S1001-6058(10)60025-X Numerical investigation of unsteady cavitating turbulent flow around a full scale marine propeller Bin Ji 1 , Xian-wu Luo 1* , Yu-lin Wu 1 , Shu-hong Liu 1 , Hong-yuan Xu 1 , Akira Oshima 2 1、State Key Laboratory of Hydroscience and Engineering, Tsinghua University Beijing, China 2、Ship and Ocean Engineering Laboratory, Mitsubishi Heavy Industries Nagasaki, Japan * E-mail: luoxw@tsinghua.edu.cn ABSTRACT: This paper treats the unsteady cavitating turbulent flow around a full scale marine propeller operated in non-uniform ship wake. The RANS method combined with k-ω SST turbulence model and the mass transfer cavitation model was applied for the flow simulation. It is noted that both the propeller performance and the unsteady features of cavitating turbulent flow around the propeller predicted by the numerical calculation agreed well with the experimental data. Due to the non-uniform wake inflow and gravity effect, there occurred periodical procedure for cavity development such as cavitation inception, growth, shrinking, etc near the blade tip for the propeller. The study also indicated that there was considerably large pressure fluctuation near the propeller during the operation. The 1st order frequency of pressure fluctuation predicted by numerical simulation equaled the rotating frequency of propeller blades. Both amplitude and frequency agreed with the experimental results fairly well. KEY WORDS: Unsteady cavitation; non-uniform wake; pressure fluctuation; full scale marine propeller 1 INTRODUCTION Cavitation may bring about a number of problems for marine propellers. The cavitating tip vortex collapse as well as the inception and shedding of sheet cavitation can cause great noise and pressure fluctuation around the ship propeller. The cavitation can also result in severe erosion to propeller blades and devices in the slipstream of the propeller such as rudders, etc. In practice, a marine propeller usually operates in a non-uniform wake field after the ship body, where the velocity and direction of the flow upstream of the propeller vary during the rotation. In fact, it is important and necessary to consider both the cavitation phenomena and the inhomogeneous inflow for the flow analysis of the marine propellers [1, 2] . Being operated in the unsteady ship wake flow, which may cause the repeating occurrence and disappearance of cavitation, marine propellers are apt to be exposed to serious vibration and erosion. Till now, most of the numerical simulations focus on the open water characteristics as well as the non-cavitating flow around the propellers in non-uniform wake [3-5] . Recently, it is believed that numerical simulation based on RANS method is effective for evaluating the vibration and erosion risks of the propellers in the unsteady ship wake flow [6-10] . In this paper, the unsteady features of cavitating turbulent flow around a full scale marine propeller were analyzed. The propeller is a typical highly skewed propeller of the training ship “SEIUN- MARU”, whose experimental data [11-13] have been frequently used by many researchers. The cavitation simulation in the wake flow field was conducted by applying a mass transfer cavitation model suitable for hydraulic machines [14] . Based on the numerical results, the propeller performance and cavitation inducing pressure fluctuation were also discussed. 2 NUMERICAL SIMULATION MODELS Based on the assumption that the water and vapor form a kind of uniform mixture in the turbulent cavitating flow, Reynolds-Averaged Navier-Stokes equations described as Eqs. 1-2 can be used. ( ) 0 m m j j u t x ρ ρ ∂ ∂ + = ∂ ∂ (1)