锥形流量计尾流流场分析

Analysis on Flow Field in Cone Wake Flow Field

锥形流量计尾流流场通过差压影响锥形流量计的流出系数,是影响锥形流量计性能的关键指标.为此,使用PIV实验的方法研究DN100口径,β为0.65,前后锥角分别为26.0°和67.5°的锥形流量计尾流流场的速度分布状况.通过PIV实验得到锥形流量计尾流中存在漩涡结构.对比PIV实验和CFD仿真得到的锥形流量计尾流漩涡处的速度分布、漩涡中心得出结论：SST k-ω湍流模型更适合锥形流量计的三维流场的仿真.利用校准后的CFD仿真得到2个规律：经过管道内径的无量纲化以后,锥形流量计尾涡的涡心、漩涡尺寸在4×104~3×105的入口雷诺数范围内仅与β相关;在此入口雷诺数范围内,同一锥形流量计的尾涡涡心的位置和漩涡长度保持稳定.

Cone wake flow field is the key factor to the cone flowmeters＇ performance because the field affects discharge coefficient through the differential pressure. The wake flow field＇s velocity distribution of cone flowmeter with DN100, β value being 0.65,front cone＇s angle being 26.0° and back cone＇s angle being 67.5° was studied by PIV experimental method. Vortex structure was found in the wake flow field of cone flowmeter. By comparing the velocity distribution and vortex core of cone wake vortex between the PIV experimental data and CFD simulation data,the conclusion has been drawn that SST k-ω turbulence model is more suitable for the three dimensional flow field simulation of cone flowmeter. Two laws have been deduced by CFD simulation：within Reynolds number range of 4×104—3×105 the vortex core＇s position and vortex＇s size of cone wake flow field are only affected by β value after nondimension disposal of the inner diameter of the meter＇s tube;vortex core position and length of vortex in the cone wake flow field remain stable to the same cone flowmeter.