低比转速离心泵叶轮径向力特性研究

Research on Radial Force of Low Specific Speed Centrifugal Pump Impeller

为了研究高速离心泵在不同工况条件下叶轮的径向力变化规律,基于Rayleigh-plesset空化模型,采用RNG k-ε湍流模型对三维Navier-Stokes方程进行封闭,对纯水工况及空化工况下离心泵叶轮所受到的径向力进行数值分析。结果表明:离心泵叶轮在纯水工况及空化工况下,离心泵叶轮所受到的瞬态径向合力均呈现出较强的规律性,一个周期内波峰及波谷数与叶轮叶片数一致;空化工况下离心泵叶轮的瞬态径向力轨迹比纯水工况下瞬态径向力紊乱,空化的发生对于离心泵叶轮径向力有不利影响;在纯水及空化条件下,离心泵叶轮所受到的径向力均在4倍叶频处最大,8倍叶频次之,且随着空化程度的加深,叶轮吸力面低压区在逐渐增加,离心泵叶轮受到的径向力脉动幅值也逐渐增加。研究为进一步优化高速离心泵在空化工况下的水力性能提供依据。

In order to study the variation of radial force on the impeller of high-speed centrifugal pump under different operation conditions,the three-dimensional Navier-Stokes equations are closed by RNG k-εturbulence model based on Rayleigh-plesset cavitation model,and the radial forces on the impeller of centrifugal pump under pure water and cavitation conditions are analyzed respectively.The results show that,(a)the transient radial resultant forces on the impeller of centrifugal pump in pure water and cavitation conditions present a strong regularity,and the number of peaks and troughs in one cycle is consistent with the number of impeller blades;(b)the transient radial force track of the impeller in cavitation condition is more disturbed than that in pure water condition,and the cavitation has a negative effect on the radial force;and(c)under pure water and cavitation conditions,the radial force on the impeller is the largest at 4 times blade frequency,followed by 8 times blade frequency,and with the deepening of cavitation,the low pressure area of impeller suction surface is gradually increased and the radial force pulsation amplitude of centrifugal pump impeller is also increased.