中文摘要：

将掺气坎布置在宽尾墩出口和阶梯溢流坝首级台阶的中间位置,能有效减小高坝泄水建筑物在高速水流作用下发生空蚀和冲刷破坏的概率。利用水气两相流模型并联合RNG k-ε模型,模拟计算不同前置掺气坎角度对溢流坝阶梯面掺气浓度和消能特性的影响,前置掺气坎角度依次取8°,10°和11.3°。其中模型采用VOF方法对自由水面进行处理,利用几何重建方式对水气面附近进行插值,采用PISO算法和非定常流算法进行计算。模拟计算结果表明,在不同前置掺气坎角度下,阶梯面平均掺气浓度沿程变化趋势为总体减小并在后几级台阶处保持不变;在靠近掺气空腔后的台阶处,沿阶梯水平近壁面凹角到凸角方向,掺气浓度的变化趋势为先减后增,而沿阶梯面垂直近壁面凹角到凸角方向,掺气浓度的变化趋势为先增后减,且同一断面的掺气浓度随前置掺气坎角度的增加而逐渐增加;在靠近反弧段的阶梯上,沿阶梯水平近壁面凹角到凸角方向,掺气浓度的变化趋势为逐渐增大,而沿阶梯面垂直近壁面凸角到凹角方向,掺气浓度的变化趋势为逐渐减小,随着前置掺气坎角度的增加,同一断面掺气浓度随着增大,且泄水建筑物消能率随之增大。

英文摘要：

The aerators are normally placedat the middle of the first step and the exit of the flaring gate pier, whichcan effectively reduce the probability of cavitation and scouring damage caused by high-velocity flow to the releasestructures of high dams. In this study, awater vapor two-phase model with RNG k-e modeling is used to simulatethe aeration on the surface of the stepped spillway and the energy dissipation characteristics; three pre-aeratorangles of 8°,10° and 11. 3° are simulated in the energy dissipater of the stepped spillway; VOF method is adoptedto deal with the free water surface; and the ways of geometry reconstruction modeling for interpolation, PISO andthe unsteady flow methods, which are the numerical simulation methods, are applied. The simulation resultsindicate that the trend of the aeration concentration is decreasing in general, and the trend stays unchanged at theend of a few steps indifferent angles of the pre-aerators; the step is near and behind an aerated cavity whosetendency of the aeration concentration decreases first and then increases along the concave angle to the lobes on thehorizontal step near the wall, while its trend is inverse on the perpendicular step near the wall. In addition, theaeration concentration increases with the enlargement of the pre-aerator angles at the same section; the step is at theogee section whose aeration concentration increases along the concave angles to the lobes on the horizontal step nearthe w all; the aeration concentration reduces along the lobes angle to the concave on the perpendicular step near thew a ll, and the aeration concentration increase with the augment of the pre-aerator angles at the same section. Therates of energy dissipation of the release structure increase with the enlargement of the pre-aerator angles.