大型泄洪洞高速水流的研究进展及风险分析

高水头、大流量泄洪洞内高速水流问题主要问题之一是水流空化引起过流表面空蚀。几个实际工程泄洪洞发生空蚀破坏的实例表明反弧段下游一定范围是容易发生空化空蚀的敏感部位，其主要原因是由于反弧段内的水流流速高，流态复杂，在水流离心力的作用下沿程压力梯度大，水流掺气条件差，缺乏有效的掺气保护。掺气减蚀是解决泄洪洞过流表面空蚀的有效措施，对水流进行三维掺气的减蚀技术有了较大进展。“龙落尾”式和 “龙抬头”式是高水头、大流量泄洪洞的两种常用布置型式，风险分析认为“龙落尾”式泄洪洞布置对地形地质的适应性更好，即使发生事故对大坝的安全威胁小，也更具有抗风险的能力。

Achievements on hydraulic problems in large spillway tunnel with a high head and large discharge flow and its risk analysis

One of the main problems cavitation damage. Several damages damaged of spillway tunnel with large discharge and high velocity flow is the of the spillway tunnels indicate that there is a sensitive part to be by cavitation downstream of the elbow. Main reasons are high speed of flow, strong turbulent flow, high gradient of pressure differences, bad aeration condition and lack of aeration protection measure. Aeration is an effective measure for the flow surface protection and there has been a great progress on the 3D aeration research resent years. There are two types of spillway tunnels, which are inclined and elbow part of tunnel near the intake and that near the outlet, the later one can be more easily adapted to the topographic and geological conditions and has a high anti-risk capability in the view point of risk analysis.