水力过渡过程中坝后式水电站流道压力空间分布特性

Spatial distribution characteristics of pressure in flow passage of hydropower station behind dam during hydraulic transient process

为了保证水电站运行安全,有效控制水力过渡过程中坝后式水电站流道压力变化,必须明确水力过渡过程中流道的三维压力分布特性。为此,以三峡右岸水电站这一典型的坝后式水电站为研究对象,对水力过渡过程中流道三维空间压力分布特性进行研究。结果显示,当导叶采用三段折线式关闭规律在额定工况下甩全部负荷时,水电站流道不同区域的压力瞬变规律具有不同的特征,同一过水断面上不同位置瞬时压力差值较大,特别在活动导叶外缘断面、转轮出口断面及尾水管肘管段出口断面,其同一时刻最大压力和最小压力的最大差值达393.207%。研究结果表明,对引水道短、断面面积大的水电站,采用三维数值模拟较传统一维特征线法更能反映水力过渡过程中流道的压力瞬变特性,为水电站的安全运行提供更好的保障。

By taking Three Gorges Right Bank Hydropower Station——a typical hydropower station behind dam as the study object,the 3-D spatial pressure distribution characteristics of the flow passage during hydraulic transient process is studied herein.The study result shows that when three-stage fold-line closure law is adopted for guide vane of the hydraulic turbine to fully reject load under the rated operation condition,the pressure transient laws in different regions of the flow passage of hydropower station have different characteristics,that is to say,the values of the instantaneous pressure differences at different positions of a same cross-section of flow are larger,especially at the cross-section of the outer edge of the movable guide vane,the cross-section of the runner outlet and the cross-section of the draft tube elbow,for which the maximum difference value between the maximum pressure and the minimum pressure at a same moment is up to 393.207%.The study result shows that for the hydropower station with short diversion channel and large area of cross-section,the 3-D numerical simulation can more accurately reflect the pressure transient characteristics of the flow passage during the hydraulic transient process if compared with the conventional method of one-dimensional method of characteristics(MOC),and then can provide a better guarantee for the safety of the operation of the hydropower station.