调压室位置和面积变化对尾水管压力的影响研究

Influences of the changes from surge chamber location and area on draft tube pressure

为了研究尾水调压室位置和面积的变化对尾水管压力值的影响,结合某水电站阻抗式尾水调压室的工程实例,运用通用的水电站过渡过程软件建立模型,并进行数值计算分析,该过程考虑了水轮机组的特性和边界条件、导叶的关闭规律以及弹性水锤的作用。结果表明:并不是尾水调压室与厂房的距离越近,越有利于尾水管压力值,调压室对尾水管最小压力的影响存在着临界位置,调压室面积的改变亦能较大程度地影响尾水管最小压力值。当调压室越过其临界位置向水电站厂房方向靠近时,尾水管最小压力值的变化幅值很小,这并不能使尾水管最小压力得到明显的改善,但是当增大调压室面积时,则会显著改变尾水管最小压力值。该结论对调压室和水电站地下厂房的布置非常有利,并有效缓解了地下洞室围岩稳定与水力过渡过程之间的矛盾。

In order to study the influences of the location and area of the tailrace surge chamber on the draft tube pressure, with the common hydropower transition process software, a model was established and used for numerical calculation and analysis, combined with an engineering example of restricted orifice tailrace surge chamber. The process considered the hydro -turbine characteristics, the boundary conditions, the closing law of guide vane and the effects of elastic water hammer. The results showed that, it was not true thatthe closer the distance between tailrace surge chamber and hydropower house, the more beneficial to the pressure value of the draft tube. There was a critical position of the draft tube minimum pressure value, the changes of surge chamber area also greatly affected the minimum pressure value of draft tube . When the tailrace surge chamber exceeded the critical position and moved towards the direc- tion of the hydropower house, the change in the minimum pressure of draft tube was small, which did not improve the minimum pressure of the draft tube significantly. However, when the area of surge chamber increased, it obviously changed the minimum pressure in draft tube. This conclusion is beneficial to the arrangements of the surge chamber and underground hydropower house, and it also alleviates the contradiction between the stability of surrounding rocks and the safety in hydraulic transition process.