摘要
以一台比转数为84.5的离心泵为研究对象,应用CFD软件对该泵作液力透平时的内部流场进行数值模拟,建立相对坐标系下的连续方程和时均Navier-Stokes方程,采用标准k-ε湍流模型和SIMPLEC算法分别对泵工况和液力透平工况进行数值模拟,得到2种工况下在不同流量时的径向力.通过对比泵工况下径向力的数值计算值和Stepanoff公式计算值,发现两者径向力大小比较吻合,表明数值模拟建立的径向力计算模型是正确的.数值模拟结果表明:液力透平工况时的最高效率比泵工况时的最高效率低约5.4%;在相同流量下透平工况时径向力普遍小于泵工况时的径向力;透平工况时径向力的大小随流量的增大而增大;当流量小于设计流量的1.1倍时,随着流量的增大,液力透平工况时径向力的方向和隔舌的夹角从146°减小到125°,但当流量大于设计流量的1.1倍时,其与隔舌的夹角随流量的增大而增大,在1.4倍的设计流量时其夹角达到144°.通过计算和实例表明在透平工况下运行时,泵轴强度仍然满足使用要求.
The internal flow field in a centrifugal pump with specific speed of 84. 5 was numerically simulated by using CFD method when it was operated as a pump and run reversely as a hydro-turbine. The Reynolds time-averaged Navier-Stokes equations,standard k-ε two-equation turbulence model and SIMPLEC method were adopted in the simulations. The radial thrust was calculated under different flow conditions in that both modes. It was confirmed that the radial thrusts predicted in pump mode is in good agreement with those estimated by means of the Stepanoff empirical correlation,suggesting the flow models adopted are correct and reasonable. It was shown that the best efficiency in turbine mode is lower than the pump mode by about 5. 4% and the radial thrust in the turbine mode is always smaller than the pump mode at the same flow rate. In the turbine mode,the radial thrust rises with increasing flow rate. The angle of radial thrust vector measured from the volute tongue is reduced to 125° from 146° as flow rate increase up to 1. 1 times the design flow rate in the turbine mode. When flow rate is higher than 1. 1 times the design flow rate,however,the angle is increased with increasing flow rate. As a result,the angle is as large as 144° at 1. 4 times the design flow rate. The results suggest that the strength of the pump shaft is strong enough and still can meet the requirement of operation in the turbine mode.
出处
《排灌机械工程学报》
EI
北大核心
2014年第1期12-16,共5页
Journal of Drainage and Irrigation Machinery Engineering
基金
"十二五"国家科技支撑计划项目(2012BAA08B05)
国家自然科学基金资助项目(51169010)
关键词
离心泵
液力透平
径向力
数值模拟
强度校核
centrifugal pump
hydraulic turbine
radial force
numerical simulation
strength check
