Flight Time Measurement Methodology for Small-Caliber Clamp-on Ultrasonic Flowmeters

Flow rate serves as a pivotal parameter in process control, holding significant importance across various domains. Ultrasonic flowmeters have garnered widespread attention due to their advantages, which include pressure-less measurement, absence of mechanical components, non-contact operation, high precision, and intelligent capabilities. The computation of Time of Flight (TOF) stands as a pivotal factor in the ultrasonic flowmeter's flow measurement using the time difference method, and its handling has remained a focal point of research. This paper initially outlines the measurement principles of the transit-time ultrasonic flowmeter. The DTCC algorithm is proposed for small-caliber clamp-on ultrasonic flowmeters, coupled with Kalman filtering to enhance measurement repeatability. A flow measurement system was established and experiments were conducted on a DN10 horizontal pipeline. In comparison to the dual-threshold detection method, the DTCC algorithm reduced the average measurement error from ±9% to ±4%, and improved repeatability from 4.05% to 0.58%, with the best repeatability reaching 0.06%. It is indicated that the DTCC method not only reduced the average error but also significantly enhanced repeatability.