溪洛渡水电站巨型混流式水轮机水力开发

针对溪洛渡水电站机组具有水头高、变幅大和单机容量为770 MW的巨型混流式水轮机水力开发的特殊问题展开研究.从水力稳定性控制的角度,讨论了水轮机水力开发条件,论证了额定转速、单位流量、单位转速、设计水头等4项关键水力参数和导叶相对高度、进出口转轮直径之比等2项关键几何参数的选择原则与匹配关系.并通过研究对比不同水力初设方案,分析不同设计参数可能引发的水力稳定性问题,结果表明:在巨型混流式机组的设计过程中应该选择较低的水力参数进行设计.研究结果显示,通过提高设计水头的水力优化措施既使得转轮叶片进水边背面初生空化远离了水轮机的运行范围,又改善了水轮机高水头部分负荷运行区转轮内的流道旋涡特性.最后根据模型验收试验证明了所采用的水力设计方法具有实际工程应用价值.

Hydraulic design of giant-scale Francis turbine in Xiluodu hydropower plant

According to high water head, large head variation and 770 MW unit capacity, a study of hydraulic design of the giant Francis turbine units in the Xiluodu hydropower plant was carried out. From the view of hydraulic stability control, the hydraulic design condition was discussed. The selecting principle and matching relationship of four key hydraulic parameters including rated speed, unit discharge, unit speed, design head as well as two important geometric parameters covering guide vane relative height and diameter ratio of the runner inlet and outlet, were demonstrated. The possible stability problems induced by different hydraulic design parameters were analyzed by comparing different preliminary design schemes, and the viewpoint of selecting low hydraulic design parameters in developing giant Francis turbine was emphasized. The results show that increasing design head can improve the vortex flow characteristics in the runner channel at the high head part load operating region, and can make the incipient cavitation at the suction surface of the blade inlet side far away from the operation region of the hydraulic turbine. Finally, it has been proved that the hydraulic design adopted has practical engineering values by the model acceptance test.