尾坎位置对坎式阶梯溢洪道水力特性影响研究

Effects of different tail bucket positions on hydraulic performances of stepped spillway

坎式阶梯溢洪道具有较高的掺气效率,然而目前为止对其详细流场结构以及消能特性开展的研究尚不多见。为此结合VOF法,采用标准k-ε紊流模型对带尾坎的阶梯溢洪道进行了三维数值模拟,研究了不同尾坎位置对其水力特性的影响。结果表明:随着尾坎向上游移动,水面线和尾坎下游侧的旋涡大小均无明显变化,但尾坎上游侧的旋涡尺度逐渐减小;对于不同体型,同一台阶凸角上流速呈先增加后不变的规律,而对于同一体型,下游台阶凸角上流速大于上游的;台阶水平面上最大压强先增加后不变,台阶竖直面上最小压强逐渐减小,而尾坎下游侧竖直面上最小压强则呈增加的趋势;台阶面上最大紊动能耗散率逐渐增加,而尾坎上的则相反,总的消能率变化甚微。

Stepped spillway has high aeration efficiency,but little research has been done on its detailed flow field structure and energy dissipation characteristics.In this paper,combined with VOF method,the three-dimensional numerical simulation of stepped spillway with tail bucket was carried out by using standard k-εturbulence model,and the influence of different tail bucket positions on its hydraulic characteristics was studied.The results showed that with the tail bucket moving to upstream,the vortex size near the water surface and the lower side of the tail bucket didn’t change obviously,but the vortex scale on the upper side of the tail bucket decreased gradually.For different body types,the velocity on the convex angle of the same step increased at first and then remained unchanged,and for the same body type,the velocity on the convex angle of the downstream step was larger than that on the upstream step.The maximum pressure on the horizontal surface of the step increased at first and then didn’t change,the minimum pressure on the vertical surface of the step decreased gradually while the minimum pressure on the vertical surface of the downstream side of the tail ridge tended to increase.The maximum turbulent energy dissipation rate on the step surface increased gradually.On the contrary,the total energy dissipation rate changed little on the tail bucket.