一种新型燕尾坎消能工的流态和消能分析

为了提高孔洞类泄水建筑物的出口消能率,同时避免出口水流堵塞和空蚀破坏,提出了一种带跌坎和反坡的燕尾坎消能工。物理模型试验表明,燕尾坎中间槽的作用使出流分成两股,水流纵向拉伸,减小了落点水舌的平均流速,并使水舌掺气增加,消能率提高;设置跌坎和反坡,通过跌坎掺气和反坡对中间股水流的引导作用,避免消能工的空化和出口流动的水流阻塞,并在中间反坡的引导下,中间水舌按预设方向入水。与传统连续坎消能工相比,该消能工消能率提高15%左右。在分析消能率影响因素的基础上,给出了所提消能工消能率的经验表达式,为孔洞类泄水建筑物的出口消能设计及施工提供了参考依据。

Study on Flow Regimes and Energy Dissipation for A New Swallow tailed Energy Dissipator

For purpose of increasing energy dissipation and avoiding flow choking and cavitation damage for orifice and tunnel release structure, the swallow tailed energy dissipator with offset and slope bottom is developed in this paper. The physical model test results indicate that the gap at the swallow tailed flip bucket center may separate the flow passed the bucket into two branches, and thus generate the jet stretched in longitudinal direction. Correspondingly, the average flow velocity of the jet is reduced, and the energy dissipation rate is increased too. Moreover, flow choking and cavitation damage are avoided, because the offset may entrain the air into the flow and the slope bottom may guide the flow direction. Furthermore, the jet from the gap may impact the downstream river following the expected direction due to the slope bottom. Compared with the traditional ski jump energy dissipator, the energy dissipation rate is improved about 15% for swallow tailed energy dissipator. Based on the analysis of the influencing factors on the energy dissipation rate, the expression of the energy dissipation rate for swallow tailed energy dissipator is proposed, which can provide reference basis for energy dissipator design and construction of orifice and tunnel release structure.