高水头大流量泄洪洞内消能工研究进展

为了降低工程投资,提高泄洪安全,防止出口冲刷、雾化和高边坡不稳定现象,近20年来国内外对各种内部消能的泄洪洞进行了研究,部分成果如旋流竖井(洞)、孔板(洞塞)和消力井等内部消能工,已应用到实际工程中。本文对这几种内部消能工的应用条件、消能效果和运行的可靠性进行了比较研究。认为旋流式和消力井式消能工适用于下游水位较低的条件,前者采用连续旋转和扩散消能,消能率高,掺气充分,可有效防止发生空蚀;后者采用井内集中消能,相对而言消能率较低。而孔板(洞塞)式消能工适用于下游高水位条件,其消能率较低,同时为了避免洞内发生高压不稳定气团流动,进水口闸门必须控制在高库水位运行。比较而言旋流式泄洪洞具有较大的优越性。

Research and prospect of interior energy dissipaters in high head and large discharge tunnels

In order to reduce investment, to improve safety and to avoid problems induced by scouring, fogging and high unsteady side slopes, many studies on interior energy dissipation tunnels have been conducted in recent 20 years. Some achievements have already been applied in engineering practice, such as swirling shafts (tunnels), orifice plugs (stoppers) and baffle wells. The authors reviewed these interior energy dissipaters and compared their application condition, dissipation efficiency and reliability. The swirling tunnel and baffle well dissipaters are suitable to be applied in the condition of low water level downstream. The swirling shaft dissipater swirls and diffuses flow continuously to dissipate energy with high dissipation efficiency, sufficient aeration and proper mitigation of cavitations. The baffle well dissipates energy concentratively in the well, with low dissipation ratio. While the orifice plugs can be applied in the condition of high water level downstream. In this case, it is easy to induce cavitation and the ratio of damping is low. The inlet gate should work in high watr level in order to avoid high-pressure unsteady air-mass flow in tunnels. It illustrates that the swirling shaft has many advantages over the other two alternatives.