低弗劳德数水流二级消力池体型参数试验研究

Experimental study on the body parameters of the two-stage stilling basin in low Froude number flow

低弗劳德数水流条件下,二级消力池是解决消能问题的一种有效途径。但至今为止,有关二级消力池的工程应用研究较多,而在体型参数和消能机理方面研究较少。为此,采用理论分析和物理模型试验相结合的方法,研究了低弗劳德数水流二级消力池体型参数及其敏感性。结果表明:消力池的长度、深度和尾坎高度等参数都存在界限值,超出界限值时第一级消力池易于产生波状或远驱水跃,而第二级消力池出池水面波动显著增大。池长小于界限值时,消力池池内流态恶化,消能率明显降低;尾坎高度越低,消波效果越好。优化后的二级消力池消能率明显提高,且二级消力池对尾水位的适应性也显著扩大。引入尾坎高度修正系数ωi,提出了各级池长和尾坎高度的计算公式。

Under the condition of a low Froude number (Fr) flow, the two-stage stilling basin is an effective way of solving the problem of energy dissipation. However, to date, there have been many applications of the two-stage stilling basin, but little research on the shape parameters and energy dissipation mechanisms. To address this issue, the body parameters and their sensitivity in the two-stage stilling basin during low Fr flow were studied by combining theoretical analysis and a physical model. The results indicated that the parameters of the stilling basin such as length, depth, and end sill height all have thresholds. When a parameter exceeds the threshold, the undular or repelled downstream hydraulic jump tends to occur in the first stage stilling basin, while the water surface fluctuation in the second stage stilling basin increases significantly. When the length of the stilling basin is less than the threshold, the flow regime in the stilling basin deteriorates, and the energy dissipation ratio decreases significantly. The lower the height of the end sill, the better the wave attenuation effect. The energy dissipation ratio of the optimized two-stage stilling basin is obviously improved, and the adaptability to the tail water level is also significantly expanded. In this study, the correction coefficient (ωi) of the end sill is introduced, and the formula for calculating the length as well as the end sill height of stilling basins is proposed.