Effect of Tip Clearance on the Cavitation Performance of High-Speed Pump-Jet Propeller

Abstract

To investigate the impact of tip clearance variation on the cavitation performance of a high-speed pump-jet propeller, Fluent software was employed for simulation calculations. The study utilized the RNG k-ε turbulence model and ZGB cavitation, conducting three-dimensional numerical simulations under both steady and transient conditions. A pump-jet propeller with a rated speed of 20,000 r/min was used to set three kinds of clearance for simulation, and the simulation proved to be reliable by comparison with the experiment. Initially, the analysis examined the effect of tip clearance on cavitation characteristics and cavitation volume under steady-state conditions, while also studying the distribution patterns of cavitation. Subsequently, the radial force and pressure pulsation of the jet propeller are analyzed by FFT processing, aiming at the influence of tip clearance on the structural strength of the pump-jet propeller. Under the design conditions, the smaller tip clearance shows better performance, while the larger tip clearance shows stronger anti-cavitation ability than the smaller clearance. In addition, the greater the tip clearance, the greater the radial force and pressure pulsation, which will adversely affect the pump-jet structure. The research results provide some references for further research on the effect of high-speed pump-jet propeller structures on performance.

Pressure Pulsation Characteristics of a Self-Priming Pump under Typical Operating Conditions

“…Thus, the RNG k-ε two-square equation model was chosen to close the Reynolds mean equation for the calculation of nonconstant turbulence. The RNG k-ε model was obtained by improving the standard k-ε model using the prevailing time-averaged strain rate to increase the effect of the average strain rate [25]. The turbulence generation and turbulent kinetic energy dissipation equations in this model are the same as in the standard k-ε model, with only the constant term modified.…”