附着空化流动下离心泵水力性能数值预测

Numerical Prediction of Hydrodynamic Performance of Centrifugal Pump under Attached Cavitating Flows

采用改进的空化模型和算法,同时耦合黏性Reynolds-Averaged Navier-Stokes方程求解技术,对空化流动条件下离心泵的水力性能进行了数值预测研究.采用具有试验数据的拱形头部圆柱体空化绕流考核了所提出的空化模型和算法的准确性和可靠性.采用数值方法研究了不同流量系数下离心泵水力性能与空化系数之间的关系,预测了空化系数对离心泵叶轮表面附着空化气泡形状的影响.数值结果表明,在相同的流量系数下,存在着临界空化系数,在临界空化系数时离心泵的水力性能突然下降,空化系数越小,离心泵叶轮表面的附着空化空腔越大,同时造成水力性能下降的越快.研究结果证明了所提出的空化模型和算法能够应用于水力流体机械空化流动时的性能预测.

The hydrodynamic performance of a centrifugal pump under a cavitating flow condition was predicted using the improved cavitation model and a viscous Reynolds-averaged Navier-Stokes solver. Numerical simulation of the flow field across an ogive headform/cylinder body was performed to confirm the accuracy and reliability of the presented methodology. The relation between the hydrodynamic performance and cavitation number of the centrifugal pump was investigated at two different flow coefficients. The influence of the cavitation number on the attached cavity shape of an impeller was predicted. The numerical results show that a critical cavitation number exists for a given flow rate. The rapid drop in head coefficient at the critical cavitation number was captured at two different flow coefficients. A lower cavitation number leads to a larger cavity shape and a more rapid drop in head coefficient of a centrifugal pump. The results also show the feasibility of the present cavitation model and algorithms for numerical prediction of a centrifugal pump under cavitation flow condition.