超深层挡水放空洞复杂体型高速水流水力特性数值模拟

Numerical Simulation of Hydraulic Characteristics of Complex High-speed Water Flow in An Ultra-deep Water Retaining and Ventilating Tunnel

针对某水电站超深层挡水放空洞复杂体型,利用3D紊流数值模拟方法,采用VOF方法追踪自由水面,对泄流能力、沿程水面线、流速、压强等水力特性进行了数值模拟分析。结果表明,该放空洞结构泄流能力满足设计要求,设计体型基本合理,有压洞转弯段出现严重的偏流,需对该段体型进行优化;弧形闸室后部两侧突扩结构最小负压0.1MPa,结构易发生空化空蚀,建议减小突扩结构尺寸,延长侧墙长度,尽量减小侧墙坡度;消能工段出口底板部位最小负压为0.1MPa,建议取消挑坎末端水平段,使水流直接挑出。

Aiming at the complex shape of an ultra-deep water-retaining and ventilating tunnel of a hydropower station,based on the 3 Dturbulent numerical simulation method,the VOF method was used to track the free water surface,and the hydraulic characteristics,such as the discharge capacity,along the water surface line,velocity,and pressure,were numerically analyzed.The results show that the venting capacity of the hollow structure meets the design requirements,the design shape is basically reasonable,and serious deflection occurs in the turning section of the pressure tunnel.The shape of the section needs to be optimized.The minimum negative pressure of the sudden expansion structure on both sides of the back of the arc gate is 0.1 MPa,and the structure is prone to cavitation.It is recommended to reduce the size of the sudden expansion structure,extend the length of the side wall,and minimize the slope of the side wall.The minimum negative pressure at the outlet floor of the energy dissipating section is 0.1 MPa.It is recommended to cancel the horizontal section at the end of the flip bucket,so that the water flow can be directly picked out.