动能修正系数对城门洞形尾水隧洞水头损失及其系数的影响

Impact of Kinetic Energy Correction Factor on Head Loss and Head Loss Coefficient of City Gate-shaped Tailrace Tunnel

基于Realizableκ-ε湍流模型及VOF算法,采用Fluent软件模拟计算某水电站尾水隧洞不同流速下的水流流态,分析了不同流速下动能修正系数的变化规律对水头损失及其水头损失系数的影响。结果表明,隧洞内的水流流速和流向对动能修正系数值均有影响,但边界条件是影响动能修正系数的决定性因素;流速越大,水头损失越大,而水头损失系数越小,且正反不同流向的水头损失及其系数亦不相等;在急变流的条件下,动能修正系数对水头损失及水头损失系数的计算有显著影响,且流速越大,影响越大;正向流速时,动能修正系数对水头损失及其水头损失系数的计算具有加大作用,而反向流速时则具有削减作用。结果可为工程应用提供参考。

Based on Realizableκ-εturbulent model and VOF model,Fluent software was used to simulate the flow regime of tailrace tunnel of a certain hydropower station under different flow velocity.Meanwhile,the law of the kinetic energy correction factor and the impact of the Kinetic energy correction factor on the head loss and head loss coefficient under different flow velocity were analyzed.The results show that both the velocity and flow direction have impact on the kinetic energy correction factor,but the boundary conditions are the decisive factors.The greater the velocity varies,the greater the head loss is,the smaller the head loss coefficient is,and both the head loss and the head loss coefficient under different direction are not equal.The kinetic energy correction factor has a noteworthy impact on the head loss and the head loss coefficient when the velocity varies rapidly,and the greater the velocity varies,the more remarkable the impact is.The kinetic energy correction factor has an enhanced effect on head loss and head loss coefficient＇s calculation under forward velocity direction,and has a cutting effect under reverse direction.The results can provide reference for engineering application.