水泵水轮机泵工况空化特性与转轮受力分析

Analysis of Cavitation Performance and Force on Runner of Pump-turbine in Pump Mode

为研究水泵水轮机在水泵工况运行时的空化特性及转轮受力情况,以某一抽水蓄能电站水泵水轮机模型为研究对象,基于Zwart空化模型和SST k-ω湍流模型,进行不同空化数下全流道三维非定常数值模拟和分析,并与实验结果进行对比验证,探讨了转轮及活动导叶中间流面的湍动能分布、叶片上的气泡体积分布和载荷分布,并定量分析了转轮受力情况。结果表明:数值分析结果成功捕获了空化的具体发展过程;随着进口总压的降低,转轮出口的湍动能逐渐增加,空泡首先在叶片吸力面靠近前缘处产生,然后沿流线向出口方向和叶片压力面扩展;由于动静干涉及蜗壳形状的不对称性,转轮径向力变化的周期性和对称性逐步被破坏,揭示了低空化数下水泵水轮机在水泵工况运行时性能变差的主要原因。

In order to obtain the cavitation performance and force on runner of pump-turbine in pump mode,the model pump-turbine in a pumped storage power station was selected as the study object. Based on SST k-ω turbulence model and Zwart cavitation model,the numerical simulation was carried out for fully-three-dimensional unsteady flow field with different cavitation coefficients and compared with the experiment results. Turbulent kinetic energy distribution on the middle stream surface of runner and guide vanes,the vapor volume and loading distribution on blades was discussed,and then force on runner was quantitatively analyzed. Results showed that the numerical analysis results can be used to capture development of the cavitation; with the decrease of the total pressure in draft inlet,the turbulent kinetic energy was increased gradually in outlet of the runner and decreased gradually in outlet of guide vanes,vapors generated at suction side of blade near the leading edge at first and then extended to the exit of runner and pressure side of blade; due to rotor-stator interaction about runner and guide vanes and asymmetry of the volute＇s shape,periodicity and symmetry of variation of radial force on the runner was gradually destroyed. The research findings can reveal the cause of operation became worse for pumpturbine in pump mode.