大石峡水电站进水口水击压力模型试验研究

Study on model experiment for water-hammer pressure at intake of Dashixia Hydropower Station

本文通过1∶21.05大石峡水电站发电引水系统水工模型,针对不同叠梁门高度取水,采用时间变态方法模拟单台机组和三台机组增甩负荷工况时,对叠梁门体及引水流道的水击压力进行测量分析。试验结果表明,(1)机组甩荷工况,叠梁门体及引水流道的水击压力符合从下游往上游、从底部往水面传播过程中逐渐衰减的规律;(2)机组增荷工况,各测点压力相对于开机前的静水压力产生一个较大的相对负压,并上下波动,波动历时较甩荷工况明显缩短,经历约20s后逐渐稳定在时均动水压力值附近。

Through the experiment with a 1∶21.05 hydraulic model of the diversion system for power generation of Dashixia Hydropower Station,the water-hammer pressures on both the body of the stop-log-gate and the diversion flow passage under the operation conditions of the load increase and load rejection of single hydropower unit and three hydropower units simulated with the method of time-scale distortion are measured and analyzed for intaking water from stop-log-gate at different heights.The experiment results show that(1)under the operation condition of load rejection of the hydropower unit,the water-hammer pressures on both the body of the stop-log-gate and the diversion flow passage conform with the laws of the gradual attentions of the pressure during the downstream to upstream and the bottom to surface propagations;(2)under the operation condition of load increase of the hydropower unit,the pressure at each measuring point produces a larger negative pressure relative to the hydrostatic pressure before the startup of the unit and fluctuates with an obvious shortened fluctuating duration if compared with that under the operation condition of load rejection,which is to be gradually stabilized around the time-averaged hydrodynamic pressure after about 20 s.