浅水圆湍射流流场特性数值模拟  

Numerical simulation of submerged turbulent round jet in shallow water

作　　者：古磊 盛立 陈科[1,2] 尤云祥 GU Lei;SHENG Li;CHEN Ke;YOU Yun-xiang(State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Collaborative Innovation Center for Advanced Ship and Deep・Sea Exploration,Shanghai 200240,China;No.92578 Unit ofPLA,Beijing 100161,China)

机构地区：[1]上海交通大学海洋工程国家重点实验室,上海200240 [2]高新船舶与深海开发装备协同创新中心,上海200240 [3]中国人民解放军92578部队,北京100161

出　　处：《水动力学研究与进展（A辑）》2021年第4期489-498,共10页Chinese Journal of Hydrodynamics

基　　金：国家自然科学基金(51979279)。

摘　　要：该文使用计算流体动力学CFD方法,基于不可压缩的Navier-Stokes方程,对圆管湍流射流在浅水密度均匀流体中的流场演化进行了数值模拟。在圆管湍流射流过程,运用Realizable k-ε的雷诺时均RANS模型;射流停止后,采用大涡模拟方法模拟大尺度漩涡在背景流体中的演化。为了考虑自由面的影响,计算域设置了空气层,并采用流体体积函数VOF方法对自由表面进行追踪。在不同的水深约束参数和雷诺数的组合下,对偶极子涡的速度场与涡量场的变化特性、垂向运动特征、涡量-流函数的变化特性以及动能和动量的演化规律等方面进行了分析,结果表明:不同水平面上偶极子涡的速度矢量场之间在涡的前端表现出较大差别,涡的前端存在垂向环流现象,流场具有明显的三维运动特征。不同水平面上垂向速度梯度的峰值和该平面上垂向涡量的峰值差不多大,垂向速度梯度不能忽略,再次证实了偶极子涡垂向运动现象的存在。偶极子涡主流动的涡量和流函数之间存在非线性关系,其散点图由中心对称的两个形似"镰刀"状的分支组成,并且随着时间的推移,"镰刀"状的区域逐渐变窄。偶极子涡主流动所在平面上的动能和动量在不同工况下均逐渐衰减,但动量的衰减速率会因自由表面及底部边界条件的影响而发生明显波动。Based on the incompressible Navier-Stokes equation,the Computational Fluid Dynamics(CFD)method is used to numerically simulate the flow characteristics of the turbulent round jet in homogeneous shallow water.The Reynolds Average Navier-Stokes(RANS)equation based on the Realizable k-εmethod is adopted for the turbulent jet flow in a circular tube.After the jet flow stops,the Large Eddy Simulation(LES)method is employed to investigate the evolution of large-scale eddy in the background fluid.In order to consider the influence of the free s urface,an air-layer is designed at the top of the computational domain,and the Volume of Fluid(VOF)method is applied to track the free surface.Under the combination of different confinement parameters and Reynolds numbers,the characteristic s of velocity field,vorticity field and the characteristics of vertical motion are discussed;then the characteristics of the vor ticity-stream function,the evolution of kinetic energy and momentum are analyzed.The results show that the velocity vector fields of dipole vortex on different horizontal planes present great differences at the front end of the dipole,there exists vertical circulation phenomenon at the front end of the dipole,and the flow field has obvious three-dimensional motion characteristics.Th e peak values of the vertical velocity gradients on different horizontal planes are almost the same as those of the vertical vor ticity on the plane,the vertical velocity gradients cannot be ignored,which confirms the existence of the phenomenon of the vertical motion of the dipole.There is a nonlinear relationship between the vorticity and the stream function of the main flow of t he dipole vortex,and its scatter diagram is composed of two central symmetrical sickle-shaped branches,and the sickle-shaped region gradually narrows over time.The kinetic energy and momentum on the plane of the main flow of the dipole vortex gradually decrease under different conditions,but the momentum attenuation rate will fluctuate significantly due to the

关 键 词：圆管潜射流 偶极子涡 垂向速度梯度 流函数 

分 类 号：O352[理学—流体力学]