漩涡的卷吸作用对多孔孔板流量计精度的影响
Influence of the Entrainment of Vortex on the Accuracy of Multi-Hole Orifice Flow Meter

计量精度的影响因素进行分析．结果表明：漩涡的卷吸作用是影响计量精度的关键因素，并得出回流通量能够表征卷吸作用的结论；多孔孔板流量计在不同的流速范围内，回流通量沿流向呈非相似性分布和相似性分布．在非相似性分布的流速区间内，流出系数 C d 的重复性较差，不同多孔孔板的重复性随着回流通量的增加而增大，流出系数 C d 波动较大．在相似性分布的流速区间内，流出系数 C d 的重复性较好，不同多孔孔板流量计的量程范围和线性度随着回流通量的增大而降低．
In order to optimize the structure of the multi-hole orifice flow meter and improve the measurement preci- sion，with the combination of experiment，CFD and the theory of jet the influence factors of multi-hole orifice flow meter measurement accuracy are studied in this paper．It is concluded that the entrainment of vortexes is the main factor affecting the accuracy of measurement，and backflow flux can characterize the strength of entrainment. In dif- ferent flow rate ranges，backflow flux presents dissimilar and similar distributions along the flow. In the velocity range of dissimilar distribution，the repeatability of discharge coefficient C d is poor and the value of repeatability increases with the increase of backflow flux；the discharge coefficient C d fluctuates strongly. In the velocity range of similar distribution，the discharge coefficient C d has good repeatability，and the linearity and range of multi-hole orifice meter decrease with the increase of backflow