针对大单宽流量、低弗劳德数消力池内消能问题,通过物理模型试验方法,对比分析消力池内加设梯形墩和悬栅消能工后水力特性和消能效果,优化梯形墩-悬栅消力池布置形式。结果表明:在低弗劳德数水流条件下,梯形墩-悬栅联合消能工断面水深分布均匀,消力池底板沿程压力分布梯度和时均压力分布系数波动幅度较小,整体稳定性较优;动能修正系数基本保持在1＜α＜2的范围内,可有效改善入池断面流速分布;消能率由传统消力池的52.25%、70.37%、75.89%分别提升至56.74%、75.95%、79.22%;梯形墩-悬栅消力池内悬栅单排等间距、高度与尾坎同高布置时,梯形墩呈双排交错形式布置在距池首0.35L左右处对于整体流态改善明显,消力池出口流速可降至0.4 m/s,消能率提高至59.63%、76.12%、79.37%,研究结果可为同类工程的底流消能问题提供一种新思路。

The layout form of trapezoidal pier and suspension grid in stilling basin is optimized through comparative analysis of the hydraulic characteristics and energy dissipation effect in the presence and in the absence of trapezoidal pier and suspended grid in stilling basin via physical model test. Results show that under the condition of water flow of low Froude number, the trapezoidal pier-suspended grid joint energy dissipator could generate uniform water depth distribution, smaller fluctuation range of pressure distribution gradient along the stilling basin floor and time-averaged pressure distribution coefficient, and better overall stability. The kinetic energy correction coefficient basically maintained in the range of 1 < α< 2, which can effectively improve the velocity distribution at the section of pool entrance. The energy dissipation rate increased from 52.25%, 70.37% and 75.89% to 56.74%, 75.95% and 79.22%, respectively. With the trapezoidal pier at about 0.35 L away from the head of stilling basin with staggered double row when the height of suspension grid is the same as that of tail ridge and arranging in single rows at equal spacing in the trapezoidal pier-suspension grid stilling basin, the overall flow pattern improves obviously, the flow rate at the outlet of stilling basin reduces to 0.4 m/s, and the energy dissipation rate increases to 59.63%, 76.12% and 79.37%. The research results offer an idea for the underflow energy dissipation of similar projects.