大型轴流泵反向发电压力脉动及流固耦合

Pressure fluctuation and fluid-solid coupling in reverse power generation of large axial flow pump

为研究南水北调东线某泵站机组反向发电的稳定性,对流道进行了全数值模拟,以研究反向发电工况的压力脉动及应力分布规律.在导叶进口、转轮进口和出口3个截面设置监测点.计算结果表明,轴流泵在反向发电工况下,转轮进口及出口处监测点的压力脉动时域图呈现周期性变化规律.压力脉动频率受转轮转频影响,集中在低频.转轮进口处中部及边缘处水流压力脉动明显,最大压力脉动发生在转轮出口处的中部水流,压力脉动幅值是转轮出口边缘处的近3倍,是转轮进口处中间及边缘的近2倍.叶轮出口处,压力脉动从轮毂到轮缘逐渐增大.研究结果表明,叶片总形变主要分布在叶片进水侧,其形变沿轮毂到轮缘方向逐渐增大;应力主要集中在叶片压力面与吸力面的根部,最大等效应力出现在叶片吸力面的叶轮根处.最大等效应力值在叶片材料安全范围内,对转轮运转机组寿命及破坏不构成影响.

In order to study the stability of the reverse power generation of a pumping station unit in the East Route of the South to North Water Diversion Project, the full numerical simulation of the flow channel was carried out to study the pressure fluctuation and stress distribution in the reverse power generation. Monitoring points in three sections of guide vane inlet, runner inlet and outlet were set up. The results show that the time domain diagram of pressure fluctuation at the inlet and outlet of the axial flow pump shows periodic variation under the reverse power generating condition. The frequency of pressure fluctuation is influenced by the frequency of runner and concentrated at low frequency. The flow pressure fluctuating in the middle and edge of the runner inlet is obvious. The maximum pressure fluctuation occurs at the middle of the runner outlet. The amplitude of the pressure fluctuation is nearly 3 times the outlet edge of the runner, and it is nearly 2 times the middle and edge of runner inlet. At the impeller outlet, the pressure fluctuation increases from hub to rim. The results of fluid-solid coupling show that the total deformation of the blade is mainly distributed in the inlet side of the blade, and the deformation increases gradually along the wheel hub to the wheel edge, and the stress mainly concentrates on the blade pressure surface and the root of the suction surface, and the maximum equi-valent stress appears at the impeller root of the suction surface of the blade. The maximum equivalent stress value does not affect the life and damage of the runner unit in the safety range of blade material.