基于PIV测量的超声波流量计内流场特性研究

采用PIV(Particle Image Velocimetry)测量手段,考察了小口径超声波流量计的流动特性。首先针对前端安装直管段时,不同流量条件下的流场特性建立基本认识,实验结果表明,在低流量条件下,流量计内流场存在明显的不稳定演变和非定常流动特征。进一步以上游前端安装球阀为典型案例,考察了安装条件对超声波流量计响应特性和测量偏差的影响。结合直管段的实验观测结果,发现此种结构超声波流量计的适应性与其流场非定常性的关系具有很好的一致性,即流场结构稳定则适应性强。此外,综合多参数的实验结果表明,雷诺数是判断小口径超声波流量计测量准确性的重要无量纲参数。

On the Internal Flow Field Performance of Ultrasonic Flow Meter Based on PIV Measurement

An experimental investigation was carried out to understand the flow performance of small caliber ultrasonic flow meter based on PIV method. The experiment was divided into two stages. In the first stage, a basic understanding about flow characteristics under different flow rate conditions was established when straight pipe is installed at inlet end. Experimental results show that under low flow condition, there are obvious instability evolution and unsteady flow characteristics in flow meter internal flow field. On the second stage, a ball valve is installed at upstream of flow meter to understand the effect of installation on response characteristics and measurement bias of ultrasonic flow meter. Combining experimental results from two stages, it is revealed that the adaptability of this ultrasonic flow meter is consistent with the unsteady characteristics of flow field, which means that the more stable the flow field is, the more adaptive the flow meter. Furthermore, comprehensive multi-parameter experimental results show that Reynolds number is a key non-dimensional parameter for measurement accuracy of small caliber ultrasonic flow meter.