溢洪道掺气坎槽后掺气水流三维数值模拟研究

Three dimensional numerical simulation of aerated flow downstream of aeration slot on spillway

高速水流泄水建筑物的某些过流部位常常发生严重的空蚀破坏,掺气减蚀是防止溢洪道空蚀破坏的重要措施。本文采用k-ε混合湍流模型封闭雷诺应力方程,利用双流体欧拉法处理自由表面及相间的相互作用,在相间作用力本构方程的构建上考虑了湍流扩散的影响,对溢洪道掺气挑坎掺气水流进行水气两相流三维数值模拟研究。研究了溢洪道沿程及断面的掺气浓度分布规律、掺气空腔特性、单宽掺气量和水面线等,探讨了掺气坎坎高、坡度、来流流速与掺气量的关系。数值模拟结果与物理模型试验结果吻合较好,验证了双流体欧拉法研究溢洪道掺气水流的可行性。研究成果为类似工程设计提供参考依据。

Severe cavitation damage has frequently occurred on water release structure of high velocity. Aeration is an important measure for prevention of cavitation erosion to spillway. This paper adopts a k-e mixture turbulence model to solve the Reynolds stress equation and a two-fluid Euler method to calculate free surface and its interaction, with turbulence diffusion included in the constitutive equation of drag force. Three-dimensional simulations were used to study the water-air two-phase axrbulent flow downstream of a bottom aerator, focusing on air entrainment concentration distribution, aeration cavity characteristics, quantity of entrained air, and water surface profiles. The relationships between aeration height, slope, velocity, and overflow discharge were also examined. The simulations have been verified with experimental data and it shows the feasibility of two-fluid Eulerian method for aerated flow on spillway. The present study would be useful and valuable for similar project designs.