带尾坎的阶梯溢洪道数值模拟研究

Numerical Investigation on the Pooled Stepped Spillway

带尾坎的阶梯溢洪道是一种新兴的阶梯溢洪道,在一定条件下可提高掺气效果和消能率,但是对于该种溢洪道内水流三维结构、压强分布以及尾坎参数对相关水力学指标的影响的研究甚少。为此,采用三维紊流数值模拟的方法计算了不同尾坎高度的阶梯溢洪道内水流流态、压强分布、流场结构、旋涡结构、消能效果等。研究结果表明:增加尾坎高度会抬升水面高程,但对水面形态影响较小;台阶水平面上压强分布呈"凹"形曲线,最小值出现在台阶中部,台阶竖直面压强最小值出现在其顶部,且台阶水平面、竖直面上压强均随尾坎高度增大而增大;旋涡强度和尺度随着尾坎高度增大而增大,但是主流流速分布无明显变化;消能率随尾坎高度增大呈上升趋势,但是变幅较小。

As the newly developed stepped spillway, pooled stepped spillwaycan improve the aeration and energy dissipation under certain circumstance, but little has been known about the three dimensional velocity field and pressure distribution in this type of stepped spillway and how the pool configuration will impact its hydraulic performances. Therefore, three dimensional numerical simulations were utilized to investigate the effect of the pool weir height on the water surface, pressure distribution, vortex structure and energy loss. The calculated results suggest that with the increasing in pool height, the water surface will increase;the pressure distribution on the horizontal step surfaces presents U-shaped versions with the minimum pressure occurring in the middle of the step surface. The minimum pressure on the vertical step surface is just below the weir top and the pressures on both horizontal and vertical step surfaces are increased with the increase of pool weir height;In addition, there is no significant change in the velocity distribution over the steps in different configurations, but the scale and intensity of the vortex under the pseudo-bottom are greater when the pool is higher, resulting in better energy dissipation, although the difference is not evident.