上游弯管对超声波流量计精度影响及整流设计

针对上游弯管流场变化对超声波流量计测量精度的影响，利用CFD对测量管道内部流场进行数值仿真模拟，并设计整流器改善由弯管导致的明显的二次流和涡流等情况，以减小超声波流量计测量误差。研究对象为基于时差法的DN15超声波液体流量计，流量范围在0.1～1.5 m~3/h内，上游弯管与流量计之间测试直管段距离为2～20D。对比超声波流量计加装整流器前后测量误差，通过实验结果验证，未整流时流量计随着直管段越短测量误差越大，安装的整流器可以改善管道内流场的速度分布，将直管段长度缩短为10D,提升超声波流量计测量误差满足在±1.5%以内，验证了数值模拟的正确性，对工程实际应用具有一定指导意义。

Influence of upstream elbow pipe on accuracy of ultrasonic flowmeter and design of rectification

Aiming at the influence of upstream elbow pipe flow field changes on the measurement accuracy of ultrasonic flowmeter, CFD is used to numerical simulate the flow field inside the measuring pipe, and a rectifier is designed to improve the obvious secondary flow and eddy current caused by the bend, so as to reduce the measurement error of ultrasonic flowmeter. The research object is DN15 ultrasonic liquid flowmeter based on time difference method. The flow range is in the range of 0. 1~ 1. 5 m 3 / h. and the distance between the upstream elbow and the flowmeter is 2 ~ 20D. Compared with the measurement errors of ultrasonic flowmeter before and after installing the rectifier, The experimental results verify that the flowmeter has a greater measurement error with the shorter the straight pipe segment when the flowmeter is not rectified. The installed rectifier can improve the speed distribution of the flow field in the pipeline, shorten the length of the straight pipe section to 10D, improve the ultrasonic flowmeter measurement error to meet within ± 1. 5% , verify the correctness of the numerical simulation, and have certain guiding significance for the practical application of the project.