复杂洞塞泄洪洞消能和空化特性研究

Characteristics of energy dissipation and cavitation for complex plug in discharge tunnel

针对高水头、大流量、出口尾水位低、消能防蚀问题突出的导流洞改建为洞塞泄洪洞工程,本文提出了"垂直洞塞+压坡洞塞+水平洞塞组"的布置形式,采用模型试验与数值计算相结合的方法分别对其消能和空化特性进行了研究。研究结果表明,该布置形式的消能率超过80%;泄洪洞各水平洞塞均无空化发生,虽垂直洞塞段出现了弱空化,但均位于水体中部,不靠近边壁,不会对建筑物产生空蚀破坏;数值模拟揭示了有压洞段详细的流场特征及消能原理。

Plug discharge tunnel is a new way for high head hydropower stations to reconstruct the discharge tunnel.However,for the plug discharge tunnel with high head,large flow rate and low tail water lever,if the arrangement of the plugs is inappropriate,serious cavitation erosion and poor effect of energy dissipation may take place.Therefore,a new plug arrangement is proposed in this paper.It is a combination of vertical gradually contracted plug,Venturi plug and horizontal gradually contracted plugs.Based on the new arrangement,the characteristics of the plug discharge tunnel are studied by experimental and numerical methods.The study results show that energy dissipation rate of the plug discharge tunnel is larger than 80%;Cavitation doesn＇t generate in each horizontal gradually contracted plug.Although weak cavitation does in the vertical gradually contracted plug,it doesn＇t result in cavitation erosion.This is because weak cavitation occurs in water and is far away from side walls of the plug discharge tunnel.Finally,the flow fields and energy dissipation mechanism of the plug discharge tunnel are exposed by numerical simulation.