Study of the Accuracy of Ultrasonic Flowmeters for Liquid

How to estimate the differential time of flight accurately is a challenging problem in the area of ultrasonic flow measurement. High time resolution is necessary, especially in a small inner diameter, short sound path measurement environment, since sound velocity in the liquid is quite fast and the order of magnitude is nanosecond. A newer method to obtain the differential time of flight is a Spline-Based algorithm. Although the calculation accuracy of a Spline-Based algorithm is higher than the common method, cross-correlation algorithm, the calculated quantity of this algorithm is huge. For this reason, an improved Spline-based algorithm is proposed to reduce the computational cost while keeping the accuracy. In addition, installation location of transducers is one of the most important factors affecting the measurement accuracy of ultrasonic flowmeter. This paper also analyzes the affection of the differential separation distance between transducers. Experiments have shown that the improved algorithm is effective and the separation distance affects the result seriously.