超声波气体流量计检测精度影响因素分析

在天然气的管道运输过程中，提高气体流量测量的精度是提高运输效率、避免安全事故发生的关键技术。利用流体力学仿真（CFD）方法建立组合双弯管及变径管道模型，定量计算修正系数，对双声道超声波流量计结构和安装位置对于管道内气体速度场的影响进行研究。通过仿真得出超声波流量计的最优声道位置，并结合实验验证了仿真结果的可信性。模拟结果表明，双弯管和变径管与超声波流量计的安装位置至少为10D才能保证流体充分流动；通过修正系数随雷诺数的变化情况得出双声道超声波流量计的最优声道位置为距管道截面中心0.25D处。研究结论对于不同性质气体的流量检测同样适用，为工业中气体运输检测精度的提高以及超声波流量计的优化提供了依据。

Factors Affecting Detection Accuracy of Ultrasonic Gas Flow Meter

For natural gas pipeline transmission, how to improve flow rate measurement accuracy is a technological challenge for improving transportation efficiency and avoiding safety accidents. By the means of the Fluent modeling method, simulation models of combined double bend pipe and contraction pipe are built. The influence of structure and installation position of dual channel ultrasonic flowmeter on velocity field of gas in the pipe is studied. The optimum sound track position of flowmeter is quantitatively analyzed through the calculation of correction coefficient of flowmeter and the simulation results are verified by experiment. The simulation results show that the installation position of flowmeter should be at least 10 times the pipe diameter to ensure the full flow of fluid in the pipe. And the conclusion that optimal sound track position is 0.25 times the pipe diameter from the pipe center is achieved at the same time through the change of correction coefficient with the Reynolds number. The research findings are suitable for flow rate measurement of different properties of gases, and are helpful to improvement of measurement accuracy in industrial application and optimization design of ultrasonic flowmeter.