中文摘要：

采用双方程紊流数学模型和自由面VOF方法，对有压泄洪洞弧形闸门突跌突扩出口段三维流动进行数值模拟，获得了空腔形态、侧墙水翅、压力分布等水力学要素，探讨了空腔冲击点涡旋对气流的吸卷作用，并研究了空腔的回水特性．计算与模型实验数据符合良好，表明数学模型对有压泄洪洞弧形闸门突跌突扩出口段复杂流场有较好的预测能力．

英文摘要：

Two-equation model for turbulent flow and volume of fluid method for free surface is applied to numerically simulate the 3D flow at radial gate region with sudden lateral enlargement and bottom drop in the outlet of pressured spillway tunnel. The hydraulic properties including the pattern of both bottom and lateral cavity, water wing on the side-wall and pressure distributions, are obtained. Air entrainment induced by vortex formed by the impact of diffused flow is explored and backflow feature in the bottom cavity is studied too. The comparison shows that there is reasonably good agreement between the physical and numerical models. The availability and power of existing numerical methods provides engineers with another tool in the design and analysis of complex flow at radial gate region with sudden lateral enlargement and bottom drop in the outlet of pressured spillway tunnel.