基于PIV方法的超声波热量表流速特性的研究

Study of the flow characteristics of the ultrasonic heat meter based on the method of PIV

近年来超声波热量表越来越广泛地应用于供暖热计量中,时差法超声波热量表的流量测量精度取决于基表圆形通道内面-线平均速度之间的关系.本文采用粒子图像测速仪PIV设备对超声波热量表基表的圆管模型在不同雷诺数范围内流动的流场特性进行了试验测量,搭建了流动测试实验台,通过PIV实验数据研究了该圆管模型广义过渡区域内的流速特性,获得了不同雷诺数下超声波传播路径上的线平均速度;并根据实验结果建立了圆管模型在超声波反射声道上面钱平均速度之间的关系,即将整个流动区域分成k系数恒定区、增大区域、不稳定区域和稳定区域,并给出了每个区域k系数的数学方程;最后,将所建立的修正模型应用于时差式超声波热量表流量检测中,验证了模型的正确性.研究结果的应用可有效提高超声波热量表的测量精度,为国家供热计量改革和推广提供理论依据.

The ulrasonic heat meter is finding wide applications with the reform of the charge method in the winter heating system.The measurement accunacy depends on the relationship between the profile and linear average velocity in the cireular channel of the basal meter.But this relationship in the transition region is complicated and the crelation studies are comparatively rare.In this article,a testing bench is built and a pipe model is used to study the flow characteristics of the heat meter via the experimental methods.The Particle Image Velocimetry(PIV)is used to measure the flow field with the diferent Reynolds number in pipes,and the linear average velocity through the ultrasonic propagation path is obtained.Based on the experimental data of PIV,the relationship od the profile-linear average velocity is studied,and it is shown that the flow region can be divided into four parts,which include constant region,increase region,instability region and stability region of the k cofficient.And the mathematics equation of each region is provided.At last,the model of k cofficient was used on the measurement of ultrasonic heat meter,and the results via the test bench verifed the validity of the model.The results of this article can be used to improve the measurement accuracy of the ultrasonic heat meter and as a theretical basis for the reform of the charge method of heaing.