混流式水泵水轮机密封间隙流动分析

Analysis of sealing clearance flow of mixed-flow pump-turbine

基于N-S方程和RNGk-ε湍流模型,利用CFD软件CFX对含减压管和转轮上冠密封间隙的某水电站原型水泵水轮机进行三维定常全流道数值模拟.分别对上冠密封间隙值为1.5、3.0、4.5 mm时,出力为60%、70%、80%、90%、100%额定出力工况下的原型水轮机进行全流道数值计算,探讨不同转轮上冠密封间隙值对混流式水泵水轮机转轮上冠密封间隙腔、顶盖与上冠间的压力腔流场的影响;分析上冠密封间隙值的大小对机组稳定性的影响.结果表明:在出力相同的工况下,顶盖下压力腔中平均压力随上冠密封间隙值增大而增大;在不同出力工况下,压力腔中平均压力随间隙值变化的程度不同,随着出力的增加变化的程度会增大,而轴向力也会随着密封间隙的增大发生变化.

Based on Navier-Stokes equation with RNG k-ε numerical simulation of three-dimensional stationary flow turbulence mode and using software CFX, the in whole flow passage of the prototype pumpturbine in a hydraulic power station with sealing clearance between its relief pipes and runner crown is conducted and the numerical calculation of whole flow passage of prototype turbine with crown＇s sealing clearance value of 1.5 mm,3 mm and 4. 5 mm is performed, respectively, under operational condition of 60%, 70%, 80%, 90M, and 100% rated output. The influence of sealing clearance value of runner crown on the flow in the crown sealing clearance chamber and the pressure chamber between head cover and crown of mixed-flow pump-turbine is then explored. The result shows that under the same output condition, the average pressure in the pressure chamber below the head cover will increase with crown sealing clearance. Under the different output condition, its changing degree with the sealing clearance will be different that, with the increase of the output, its changing degree may increase and the axial hydraulic thrust may also vary with the increase of sealing clearance.