长距离无压引水隧洞水气两相流数值模拟

Numerical simulation of water-air two-phase flow with free surface in long tunnel

采用计算流体力学软件STAR-CD的水气两相流耦合VOF法的三维标准k-ε紊流模型对长距离无压引水隧洞进行了模拟计算。计算中引入考虑糙率影响的壁面函数,并用PLIC方法对水气交界面进行了重构。通过与引额济乌一期工程尾部调节水库泄水洞模型试验结果的对比表明,计算结果与实测数据基本吻合,说明所采用的数学模型是可行的。应用此模型对新疆八十一大坂长距离无压引水隧洞水气两相流进行了模拟,结果表明长距离无压引水隧洞在隧洞进口处出现水流扰动区,在主支洞交汇处出现水流漩涡区,在隧洞出口处出现水流突变区,并分析了隧洞沿程过水面积、空气流量以及支洞补气量的变化规律。

The three-dimensional standard k - ε model coupled with the Volume of Fluid （VOF） method was applied to numerically simulate the water-air two-phase flow with free surface in long tunnel. The wall function expressing the effect of wall was introduced and the PLIC method provided by the software STAR-CD was used to reconstruct the water-air interface for determination of water surface. The validity of this method was verified by the model test of a flood releasing tunnel. On this basis the method was applied to calculate the flow in a long diversion tunnel in the Xinjiang Autonomous. The result shows that a water flow disturbance zone occurs to the tunnel inlet, vortex zones exist in the branch tunnels at the vicinity of intersection and the flow depth at the outlet of the tunnel drops sharply. Besides, the profile of water surface and the air flow along the distance of tunnel as well as the effect of air supply of branch tunnels are studied.