水泵水轮机导叶开启瞬态过程数值分析

Numerical analysis of transient process of guide vane opening of pump-turbine

基于滑移网格和动态网格相结合的思想,实现水泵水轮机二维模型在转轮区转速增大和活动导叶开启共同作用下引起的瞬变流场的数值模拟,得到速度、压强随时间的瞬态变化规律,探讨水泵水轮机导叶开启过程的流场特性;对预开一对导叶下的启动过程进行模拟,分析导叶区域的内部流场瞬态演化过程.结果表明:导叶开启过程中叶片对导叶区域的干涉作用由强变弱,速度分布的均匀性和周向对称性逐渐提高;设置预开一对导叶后,破坏了初始阶段流动的对称性,导致流动的不稳定性增强,活动导叶与转轮之间的压强波动幅度增大,对机组运行的稳定性有一定影响.

Based on the idea of combination of sliding mesh with dynamic mesh,the numerical simulation of the transient flow field in the two-dimensional model of pump-turbine is implemented in the case of impeller speed rising and guide vane opening so that the pattern of transient variation of velocity and pressure with time will be acquired and the flow field characteristics during the opening of the guide vanes will be explored.Besides,the start-up process is also simulated in the case of pre-opening apair of guide vanes and the evolution process of the flow field around guide vanes is analyzed.The results show that the interference of the impeller blades with the guide vanes area during the guide vane opening will change from strong to weak and the uniformity and the circumferential symmetry of velocity distribution will be improved gradually.The setting of guide vane pre-opening pair will deteriorate the flow symmetry at the initial stage,leading to the enhancement of the flow instability and the increase of the amplitude of the pressure fluctuation.It will have a certain effect on the stability of the unit operation.