竖井式抽水蓄能电站进/出水口的水力特征

采用小孔扩散方式所建立的轴对称二维切片模型和二维轴对称数值模型,对抽水工况的出流特性和尾流的水流摆向进行了研究.试验与数值模拟结果显示,抽水工况下出流可视作射流,水流摆向与水位有一定关系,高水位时摆向河床,低水位时摆向水面;三维模型对比试验显示,抽水工况下采用防涡板结构时的进/出水口水头损失系数可达0.61,而无防涡梁、阶梯防涡梁和水平防涡梁等3种结构的水头损失系数范围为0.44~0.48;发电工况下水头损失系数均接近0.40.试验结果显示,竖向扩散段的扩散角小于9°时能保证配水均匀.采用2~3倍发电流量观察发电工况时漩涡的形成,试验显示漩涡的变化特征随水位发生变化：高水位时在进/出水口顶盖上部形成单一的漩涡;当水位降低到一定程度后,大环流转化为若干个漩涡,漩涡数量与导流墩数量相同.两个进/出水口同时运行时,环流之间相互干扰,可能形成一顺一逆环流.

Study on hydraulic characteristics of vertical pipe inlet/outlet of pumped storage plants

The 2D slip physical hydraulic model and axisymmetric numerical models were applied to investigate the wake flow direction of the vertical pipe inlet/outlet outflow.The results of the 2D model experiment and the axisymmetric numerical simulations showed that the outflow of vertical pipe with the cover plate performed as jet flow,and the direction of wake flow changed with the water level.The wake flow would shift to the surface layer when the water depth was small and it would turn to the bed when the water depth was high.The 3D model experiment showed that the outflow head loss coefficient was 0.61 with an anti-swirl plate mounted above vertical inlet/outlet,and the factors were about 0.44～0.48 for other types of structures of statewide anti-swirl beam,flat anti-swirl beam or non anti-swirl beam.The inflow head loss factors were about 0.4 for all types of intakes.The model experiment results also suggested that it was able to provide uniformity flow with pipe diffuse angle of less than 9°.An individual big spiral vortex appeared above the inlet structure during the inflow model experiment under the conditions of high water level.As the water level went down,the big spiral vortex would collapse into several small ones,and the number of spiral vortexes was same as the number of the guide walls.When two intakes were wor-king at the same time,spiral vortexes would interact,one was dextrorotatory and another was levorotatory.