A High-Accuracy Ultrasonic Flow Measurement Method Based on Voltage Amplitude Difference

High accurate flow measurement is important for process monitoring. The clamp-on ultrasonic flow meter is a type of non-invasive and non-intrusive flow measurement technique. However, the traditional used transit-time difference method in the clamp-on ultrasonic flow meters cannot achieve accurate measurement under small flow rates because the measurement accuracy is limited by the equipment’s sampling rate and system error. This article proposes a novel flow measurement method by using signal voltage amplitude difference (VAD). The transit-time difference information is converted into voltage amplitude difference information, therefore the measurement error due to sampling rate at small flow conditions can be eliminated and the measurement accuracy is improved. The analytical solutions of ultrasonic vibrations are analyzed and a new “M” shaped ultrasonic transducer design is introduced. The new transducer can generate and receive downstream and upstream ultrasonic signals simultaneously. In this scenario, the VAD method can be used for flow measurement. In addition, a variety of influencing factors are analyzed to further improve the measurement accuracy of the proposed method. Experimental results indicate that the combined uncertainty of the VAD method exhibits a 62.5% reduction compared to that of the transit-time difference method.