充水阶段无压输水洞岔洞段水力特性

长距离无压引水洞岔洞是影响水流流态和分流量的关键水工建筑物之一,充水阶段流态复杂。通过Fluent软件对不同入口流量、岔洞夹角下的无压卜型岔洞充水阶段进行了数值仿真研究,并通过模型试验对不同入口流量下水流平稳后的岔洞段各监测断面水深及支洞分流比进行了验证。结果显示,充水阶段支洞分流比对入口流量敏感性小,岔洞夹角在15°～45°范围内变化时,分流比变化较大。另外,岔洞夹角增至60°时,侧支洞外侧上部水流出现回流区。岔洞夹角对总干水面线影响较小,岔洞段各断面水位随入口流量增加而升高。

Hydraulic characteristics of non-pressure branch tunnel during the water filling stage

The long-distance,non-pressure branch tunnel is a hydraulic structure that affects the flow regime and discharge ratio. In the water-filling stage,there are complex flow regimes in the branch tunnel. In this paper,the numerical simulation calculation in the non-pressure branch tunnel at the water filling stage,considering different inlet flows and diversion angles,was carried out by the FLUENT software. At the same time,the water depth at each monitoring station and the discharge ratio for the branch tunnel,after the water flow is stable for different inlet flows,were verified by the model test. The results show that the inlet flow during the water filling stage has little effect on the discharge ratio,which depends mostly on the diversion angles,between 15° and 45°,considered in the simulation. In addition,a recirculation zone appears in the upper flow outside of the lateral branch when the diversion angle is increased to 60°. The change in the diversion angle has little effect on the main tunnel water surface line. The water level in each tunnel section increases when the inlet flow increases.