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超声波流量计(UFM,Ultrasonic Flow Meter)通过测量管路中顺流和逆流方向的超声波传播时间变化计算流速,因此超声波传播时间的准确测量对流量计的精度影响至关重要.对超声波流量计的测量方法进行研究,从环境温度的变化、时间测量的准确性、不确定度的计算3个方面,对比超声波传播时间差法和频率差法对流量测量精度的影响.通过超声波流量测量实验,验证了在流量计未校准的情况下,与频率差法相比,时间差法的测量精度更高,且其校准系数曲线的线性度更好,校准后可在全流量范围内获得更高的测量精度.
Ultrasonic Flow Meter (UFM, Ultrasonic Flow Meter) Accurate measurement of the ultrasonic propagation time is of crucial importance to the accuracy of the flowmeter by measuring the flow rate of the ultrasonic flow in the forward and reverse directions in the pipe. The influence of ultrasonic time-difference method and frequency difference method on the accuracy of flow measurement is contrasted from three aspects of the change of ambient temperature, the accuracy of time measurement and the calculation of uncertainty.According to the ultrasonic flow measurement experiment, When the flowmeter is not calibrated, the time difference method is more accurate than the frequency difference method, and the linearity of the calibration coefficient curve is better. After calibration, higher accuracy can be obtained in the whole flow range.