喷水推进器转速波动工况下瞬态特性研究

In order to analyze the transient characteristics of the water-jet propulsion under the condition of rotating speed fluctuation, the hexahedral structured grid was used to divide the internal flow field of waterjet propulsion. Numerical simulation was carried out for water-jet propulsion whose rotating speed was fluctuating according to sine function based on RANS equation, SST k-ω turbulence model and Zwart cavitation model. The accuracy of numerical calculation method was verified by comparing the numerical results of water-jet pump with the experimental data, and the numerical results agreed well with the experimental data. The results show that in the process of rotating speed fluctuation, the head has a good followability along with the rotating speed change, and the flow rate completely lags behind the rotating speed change. At the same rotating speed, there are obvious differences between the acceleration process and deceleration process. In the deceleration process, the pressure in the inlet duct is lower, and the cavitation area at the leading edge of the blade is larger. Moreover, quasi-steady flow field cannot describe the characteristics of the transient flow field accurately. The change of the dimensionless cavity area lags behind the change of the rotating speed. When the instantaneous rotating speed is higher than the design rotating speed, the dimensionless cavity area increases rapidly and the maximum value can reach 8.02%. When the instantaneous rotating speed is lower than the design rotating speed, the dimensionless cavity area is less than 1% and the anti-cavitation performance is great.