摘要
空化余量是泵非常重要的性能指标之一,目前主要依靠试验来确定。如何在离心泵设计过程中较为准确地预测出必须的空化余量对优化设计和提高运行稳定性等方面十分重要。针对离心泵运行过程中发生空化时的流动特点,基于Rayleigh-Plesset方程来描述空泡生长和溃灭过程的空泡动力学模型,采用混合空化两相流模型和三维全流道两相流流动数值模拟技术,探索通过数值试验来预测空化余量的方法。对一低比转速离心泵进行全流道空化流数值模拟,通过改变NPSHa来模拟试验工况,数值模拟预测出各模拟试验工况下的扬程、叶片表面压力分布、叶片表面空化发生区域以及流道内空泡体积率分布,从而预测该泵的NPSHr,其预测结果与试验值的误差小于10%。
NPSHr is one of the most important performance of a pump, which is mainly derived from hydraulic model tests. How to accurately predict a pump＇ s NPSHr is a great challenge to optimize design and enhance operating stability. Based on cavitating flow feature inside a centrifugal pump, bubble growth and implosion are calculated from the Rayleigh - Plesset equation which describes the dynamic behavior of spherical bubble, filled with vapor and gas, as a function of the local pressure. A numerical simulation of two - phase flow with a homogenous mixture of gas and liquid inside a centrifugal pump was employed to explore the methodology of predicting NPSHr with numerical test approach. A numerical simulation for cavitating flow inside a low specified speed centrifugal pump was con- ducted in whole passage. The numerical test was carried out for the centrifugal pump at different operating conditions by varying NPSHa, which is similar to hydraulic tests, NPSHr for this pump can be predicted from the head - drop curves which were computed by numerical simulation. Meanwhile, the pressure distribution on blades surfaces, districts where cavitation occurred, and vapor vol- ume fraction inside the flow passage of a pump could be used to investigate the eavitating flows and helpful to determine NPSHr value. It showed that the predicted result agreed with the measured results by hydraulic tests and the maximum error was within 10%.
出处
《西华大学学报（自然科学版）》
CAS
2013年第2期29-32,共4页
Journal of Xihua University:Natural Science Edition
基金
"流体及动力机械"省部共建教育部重点实验室(SBZDPY-11-7)
四川省教育厅成果转化培育项目(11ZZ002)
关键词
离心泵
空化流
两相流
数值模拟
性能预测
centrifugal pump
cavitating flow
two - phase flow
numerical simulation
performance prediction
