导叶不同开度下水泵水轮机内流特性分析

为研究预开导叶不同开度下的内流特性,以某抽水蓄能电站水泵水轮机模型为研究对象,基于SST k-ω湍流模型,进行预开导叶不同开度下全流道三维非定常数值模拟和分析,并与试验结果进行对比验证.探讨活动导叶与转轮之间,以及转轮内的旋涡分布情况,定量分析了转轮受力情况和尾水管压力脉动.结果表明:在同步导叶开度一定的情况下,随着预开导叶个数的增加,其过流部件的流量将会增大,且存在于活动导叶和转轮区域的高速水环也会被破坏,形成紊乱的旋涡.从转轮区域看,在叶片的液道内形成不同的涡结构,其分布的不均匀性将直接影响转轮的受力情况.随着预开导叶个数的增加,这种情况将更为明显,转轮径向力的幅值逐渐增大.进一步分析尾水管压力脉动发现,尾水管压力脉动幅值也随着预开导叶个数的增加而增大,从而导致机组振动加剧、运行不稳定.

Analysis of internal flow characteristics of pump-turbine under different openings of misaligned guide vanes

In order to obtain the internal flow characteristics of misaligned guide vanes under different openings,a model of pump-turbine in a turbine storage power station was taken as the research object.Based on SST k-ωturbulence model,the numerical simulation was carried out for full three-dimensional unsteady flow field under different openings of guide vanes and compared with the experiment results.The vortex structure between the guide vanes and the runner and inside the runner was discussed,and the force on runner and the pressure fluctuation in draft tube were quantitatively analyzed.The results show that the flow rate of the over current component will increase when the number of pre-opening guide vanes increases,and the high-speed water ring existing in the guide vane and runner area will be destroyed,forming a disordered turbulence.From the perspective of the runner area,different vortex structures are formed in the fluid passage of the blade.The distribution of these vortex structures is uneven,which directly affects the force of the runner.This situation is more obvious when the number of pre-opening guide vanes increases.As the number of pre-opening guide vanes increases,the amplitude of the radial force of the runner gradually increases.Further analysis of the pressure fluctuation of the draft tube shows that the change of the pressure fluctuation of the draft tube is also the same.As the number of pre-opening guide vanes increases,the increase of the pulsation causes the vibration of the unit to intensify,resulting in unstable operation of the unit.