三种空化模型在离心泵空化流计算中的应用评价

Applicative evaluation of three cavitating models on cavitating flow calculation in centrifugal pump

为寻求一种更好的数值计算方法来模拟离心泵空化流,该文比较了Zwart-Gerber-Belamri模型、Kunz模型和Schnerr-Sauer模型在离心泵空化流模拟中的适用性。在3个不同的流量系数(φ=0.082、0.102、0.122)下,将每个模型的数值计算结果与试验结果进行对比,发现设计流量系数和小流量系数下Kunz模型的模拟结果与试验值最为吻合,大流量系数下Zwart-Gerber-Belamri模型的模拟结果更接近试验值。分析了φ=0.102时Kunz模型得到的空化流场,发现随着空化数的减小,空泡首先在叶片吸力面进口边附近产生,然后沿叶片吸力面向出口方向和叶片压力面扩展;叶轮流道总压系数的下降主要发生在上游断面,空化的发展对下游断面的影响很小;空化对叶片表面载荷分布影响较大。

To find a better numerical method to simulate the cavitating flows in the centrifugal pumps, the influences of three widespread cavitation models （Zwart-Gerber-Belamri model, Kunz model and Schnerr-Sauer model） were verified on the numerical predictions of the centrifugal pump performances. The simulations were executed with three different flow coefficients, from 0.082 to 0.122. Subsequently, the numerical results obtained by different cavitation models were compared to the measured values, respectively. The prediction accuracy of Kunz model were higher than the other two cavitation models with the design flow coefficient and the small flow coefficient, and the simulation results under the Zwart-Gerber-Belamri model with the large flow coefficient was close to the experimental data. In addition, the cavitating flows of the centrifugal pump obtained by Kunz model with ~0=0.102 was analyzed, and the bubbles generated at the suction side of blade near the leading edge at first and then expanded to the outlet of impeller with the decreasing of cavitation number; the decreasing total pressure coefficient occurred in the upstream of the impeller passage principally, while the downstream approximately remains unaffected with the development of cavitation; the load on the blade was greatly affected by cavitation.