中文摘要：

宽尾墩＋阶梯溢流坝＋消力池一体化消能工很好的解决了我国由于大单宽流量和高水头等引起的高速水流问题,该消能工常采用过渡阶梯连接宽尾墩与阶梯溢流坝。本文基于阿海水电站溢流表孔,应用水汽两相流VOF计算方法的三维RNG k-ε湍流数值模型,速度与压力采用PISO耦合的算法方式,利用几何重建格式对水气交界面附近进行插值的非恒定流迭代求解,对1个高2 m、宽1.5 m台阶组成的过渡阶梯,2个高2 m、宽1.5 m台阶组成的过渡阶梯,3个高2 m、宽1.5 m台阶组成的过渡阶梯和原工况四种方案的宽尾墩＋阶梯溢流坝＋消力池一体化消能工进行三维流场数值模拟。结果表明：各方案均在首级阶梯内产生负压,且前三种工况在首级阶梯固壁压强分布基本一致,竖直壁面最大负压均出现在桩号22.56 m附近,其最大负压（-0.899 k Pa）较原工况最大负压（-4.469 k Pa）小。同时前三种工况水平壁面最大负压（-0.597 k Pa）较原工况最大负压（-3.898 k Pa）也小。即过渡阶梯的台阶数对负压分布影响不大。在消能方面,有2个台阶组成的过渡阶梯对阶梯溢流坝的消能率最高（为34.205%）,其中过渡阶梯的首级台阶对阶梯溢流坝的消能效果影响最大。

英文摘要：

The energy dissipator of flaring gate pier, stepped spillway and stilling basin has effectively solved the problems of high-velocity flows that have occurred under large discharge per unit width and high working head of the dams in China. It often adopts a transition ladder connecting the flaring gate pier to stepped spillway section. This paper presents a numerical simulation study on the transition ladder design for the spillway of Ahai hydropower station, using a 3-D flow model equipped with a RNG turbulence model, water-gas two-phase VOF method, PISO algorithm for velocity-pressure coupling, and a geometry reconstruction scheme for unsteady flow iteration solution to generate free surfaces. The 3-D flow simulations were conducted for four design schemes of this integrated energy dissipator： three schemes with transition ladders of one step, two steps and three steps respectively and the same step sizes of 2 m high and 1.5 m wide, and one scheme for the primary design with no transition ladder. Simulations show that in all the ladder schemes, negative pressure occurs in the head ladder and pressure on the solid surface of the head ladder is distributed in the same pattern. And in all the three cases, the lowest pressure on vertical step faces is negative and occurs at Section 22.56 m, with its value（-0.90 k Pa） significantly higher than that of the primary design case（-4.47 k Pa）. On the horizontal step faces of the transition ladder cases, the lowest pressure（-0.60 k Pa） is also higher than the corresponding value（-3.90 k Pa） of the primary design. This indicates that the number of ladder steps has no considerable effects on the negative pressure or its distribution. Its effect on energy dissipation, however, is significant. Our results reveal that of the three ladder schemes, the two-step transition ladder can achieve the highest energy dissipation ratio（34.2%） and its head step has a much greater dissipation effect than the other one.