V形内锥流量计关键参数对流出系数的影响

将计算流体动力学仿真试验和实流物理试验相结合，剖析V形内锥流量计的流出系数特性，探索不同等效直径比β、前后锥角以及雷诺数等对流出系数的影响规律。湍流模型为RNG k-ε模型。针对100 mm口径，设计了β值分别为0.50、0.65、0.85，前锥角分别为40º、45º、50º，后锥角分别为120º、130º、140º，共27种组合的V形内锥体，仿真介质为水，温度为293 K。经过数值模拟试验，获得了27条内锥流量计流出系数特性曲线。为进一步验证仿真试验结果，在已有实流试验系统的基础上，建立针对V形内锥流量计的专用自动标定平台。两类试验数据比较发现：内锥流量计的流出系数不仅和雷诺数有关，还与等效直径比β及前后锥角相关。首先，β值越大，流出系数越小，且β值越大，流出系数更易受雷诺数的影响；其次，β值相同时，前锥角对流出系数具有决定性的影响，而后锥角对流出系数的线性度具有一定程度的影响；第三，较大的前锥角可减弱雷诺数对流出系数的影响。数值模拟试验预测平均误差约5%，最大值小于10%。

Influence of Key Factors on Discharge Coefficient in V-cone Flowmeter

By combining the computational fluid dynamics (CFD) simulation experiment with the real physical calibration experiment, this study is to discover the characteristics of the discharge coefficient of V-cone flowmeter. Here, the turbulence model is RNG k-ε. The key factors include different values of equivalent diameter ratio β, fore-and-aft V-cone angle and the Reynolds number. The pipe diameter of all the prototypes is 100 mm with the β, 0.50, 0.65, 0.85, respectively, the fore V-cone angle, 40º, 45º, 50º, respectively, the aft V-cone angle, 120º, 130º, 140º, respectively. Therefore, there are 27 tested models in all. The medium for simulation is water of 293 K. The 27 characteristic curves are obtained from the numerical simulation. In order to further verify the computational results, a new automated special device for calibration is set up, which depends on an established water calibration and test device. From the both test data, we discover that the discharge coefficient of V-cone flowmeter relates not only to the Reynolds number, but also to the values of equivalent diameter ratio β, fore-and-aft angles of V-cone. Firstly, the discharge coefficient increases while the β is decreased, and it is influenced more easily by Reynolds number while the β is increased. Secondly, if the β keeps the same value, the fore V-cone angle is crucial, and the aft can influence the linearity to a certain extent. Thirdly, larger fore V-cone angle will weaken the influence of the Reynolds number. The average error of simulations is approximately 5%, the maximum, less than 10%.