变水头流量标准装置水柜产生漩涡的数值模拟与分析

Numerical simulation and analysis of flow in a variable waterhead reservoir in the presence of vortex

目前一般使用静态容积检定流量仪表,但这种方法建立在定常流动的基础上而且存在测量结果不确定等局限。为研究自由表面漩涡生成与演化过程对变水头标准装置的不确定度影响情况,采用流体体积法结合大涡模拟法,在Ansys+Workbench+FLUENT数值仿真软件平台环境下再现了自由表面漩涡发展过程的典型流态,并根据其特点选取4个典型阶段,并对其中B型和D型的径向速度、切向速度及轴向速度沿水柜半径方向的变化情况进行重点分析。最终得出涡量向涡核中心集聚导致水柜产生漩涡现象以及当水位下降到水柜高度的21.4%左右时自由液面开始出现下凹现象。

Static Volume method is generally introduced into flow meters, the method is based on steady flow and has some limitations such as uncertainty of measurement results. To study the uncertainty of variable waterhead reservoir in the process of vortex generation and evolution of free surface, large eddy simulation and volume of fluid are introduced into simulating the process of the presence of vortex in a variable waterhead reservoir using the numerical software platform Ansys Workbench FLUENT. According to the flow characteristics, four typical stages of the developing process were selected, and the regularities of the radial velocity, tangential velocity and axial velocity of B-type and D-type free surface vortex along the direction of radial were mainly analyzed. The numerical simulation results show that the vortexs gather towards the center causing the free surface to depress and eventually become vortex and when the water level drops to about 21.4% of the height of the variable waterhead reservoir, the free surface begins to appear depressed.