A Transmission-mode Ultrasonic Sensor for Two-Phase Flow Concentration Measurement

• 1、Tianjin Key Laboratory of Process Measurement and Control, School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072

Abstract：Phase concentration of two-phase flow is of significance in industrial processes and academic researches. The detecting techniques are required non-intrusive or non-contact with the measured fluid. Ultrasonic waves can travel within fluid without severely disturbing the flow field, and thus can be used for phase concentration measurement of two-phase flow in the transmission mode. This work applies the linear frequency modulation (LFM) to a ultrasonic measurement system. The LFM is used as the exciting signal to provide high energy transmission signals, owing to its advantages of large time-bandwidth product. The receivers process the measured sound waves by pulse compression method in order to increase system resolution and signal to noise ratio. A ultrasonic system is built with FPGA in the philosophy of modular structure. A set of static experiments were carried out and results indicate that the presented system is sensitive to the diameter of simulated bubbles in the pipe filled with water, and a relationship between the measurement voltage and bubble diameter is proposed.

Keywords： Measurement techniques and automatic devices Ultrasonic sensor Two-phase flow Phase concentration, Linear frequency modulation