Numerical simulation of tip clearance impact on a pumpjet propulsor

Numerical simulation based on the Reynolds Averaged NaviereStokes (RANS) Computational Fluid Dynamics (CFD) method had been carried out with the commercial code ANSYS CFX. The structured grid and SST k-ω turbulence model had been adopted. The impact of noncondensable gas (NCG) on cavitation performance had been introduced into the Schnerr and Sauer cavitation model. The numerical investigation of cavitating flow of marine propeller E779A was carried out with different advance ratios and cavitation numbers to verify the numerical simulation method. Tip clearance effects on the performance of pumpjet propulsor had been investigated. Results showed that the structure and characteristics of the tip leakage vortex and the efficiency of the propulsor dropped more sharply with the increase of the tip clearance size. Furthermore, the numerical simulation of tip clearance cavitation of pumpjet propulsor had been presented with different rotational speed and tip clearance size. The mechanism of tip clearance cavitation causing a further loss of the efficiency had been studied. The influence of rotational speed and tip clearance size on tip clearance cavitation had been investigated.