水电能源科学

为深入明确尾坎形式对阶梯溢洪道消能特性影响并对其进行体型优化，采用计算流体力学方法对某工程阶梯溢洪道进行数值模拟。通过定义尾坎边长与台阶高度的比值a/H为尾坎尺寸，在原体型基础上提出4种不同尾坎尺寸的体型，对比分析各体型溢洪道内水面线、流场结构、压强分布、空化数及消能率的变化规律。结果表明，尾坎布置对于水面线的影响并不显著，仅在上游局部区域出现水面抬升且抬升幅度较小，水流均呈现滑行流态；台阶面旋涡范围与强度随尾坎尺寸的增加而增大；台阶水平面最小压强出现在相对台阶竖直面0.4倍长度附近，台阶竖直面最小压强在相对台阶水平面0.9倍高度附近，两者压强最小值均随尾坎尺寸的增加而增大，尾坎迎水面最大压强位于其底部，并随着尾坎尺寸的增加逐渐减小，前两级台阶竖直面出现了不同程度的负压区；台阶面紊动能和紊动能耗散率均随尾坎尺寸的增加呈下降趋势；消能率随尾坎尺寸的增加而增大，但增长幅度较缓，结合消能效果与空化风险，a/H=0.53的体型较优。

To investigate the impact of tail-end configurations on the energy dissipation characteristics of stepped spillway and to optimize its shape, computational fluid dynamics was used to conduct a numerical simulation of an engineering case. By defining the ratio of the tail-end side length to the step height(a/H) as the key dimensionless parameter, four optimized configurations with different a/H ratios were proposed based on the original design. A comparative analysis was performed on the variation patterns of water surface profile, flow field structure, pressure distribution, cavitation number, and energy dissipation rate for each configuration. The results indicate that the impact of placement of the tail-end on the water surface profile is not significant, causing only minor local uplift in the upstream region, with the flow maintaining a skimming regime. The vortex scale and intensity on the step surfaces increase with the a/H ratio. The minimum pressure on the horizontal step face occurs near 0.4 times the step length from the inner corner, while on the vertical face, it occurs near 0.9 times the step height. Both minimum pressure values increase with the a/H ratio. The maximum pressure on the upstream face of the tail-end is located at its base and decreases as the a/H ratio increases. Negative pressure zones of varying degrees were observed on the vertical faces of the first two steps. Both the turbulent kinetic energy and its dissipation rate on the step surfaces show a decreasing trend with an increasing a/H ratio. Although the energy dissipation rate increases with the a/H ratio, the rate of increase is gradual. Considering both the energy dissipation effect and cavitation risk, the configuration with a/H= 0.53 is identified as the superior design.