基于CFD的超声波气表结构与流动特性研究

Research on structure and flow characteristics of ultrasonic gas meter based on CFD technology

基于计算流体力学（CFD）技术,对超声波燃气表进行了结构改进,并以声道测量段线面速度比K系数及其标准差ΔK来评价其性能。共涉及a～e 5种方案,结果表明,不同基表结构的K系数在不同流量下呈现出不同的变化趋势,且随流量的增大先减小而后趋于平缓。在小流量区前半部分,各方案K系数变化率大致相同,在小流量区后半部分,除方案a外各方案K系数曲线近似平行;在中流量区方案c～d的K系数变化率基本一致;在大流量区方案a～d的K系数曲线与横坐标轴近乎平行,方案e虽有一定的坡度,但其线性度较好。通过比较不同设计方案的标准差ΔK发现,方案e的流体速度分布最为均匀,但压损稍大。为后续超声波燃气表的性能研究、设计和结构优化提供了理论依据和参考。

Based on computational fluid dynamics（CFD） technology, the structure of the ultrasonic gas meter is improved. Besides, the performance of the ultrasonic gas meter is evaluated by using the K coefficient of the path measurement section and the standard deviation ΔK. This study involves five schemes which are from a to e. The results show that the K coefficients of different gas meter structures show different trends under different flow rates. As the flow rate increasing, it first decreases and then tends to be flat. In the first half of the small flow area, the rate of change of the K coefficient of each scheme is roughly same. In the latter half of the small flow area, the K coefficient curve of each scheme except scheme a is approximately parallel. The change rates of K coefficient of scheme c to d are approximately same in the medium flow area. The K coefficient curves of scheme a to d in the large flow area are almost parallel to the axis of the abscissa. Although the K coefficient curve of the scheme, scheme e has a slope, the linearity is better. Compared with the standard deviations ΔK, it can be found that the most uniform flow velocity distribution is obtained in scheme e. But, the pressure loss is a little bit large. Research results show that this study provide theoretical basis and reference for the performance, design and structure optimization of the subsequent ultrasonic gas meter.