科研之友
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摘要
Transmission of ultrasonic wave in fluid does not cause disturbance and pressure loss to the flow field, which is therefore an important test means of two-phase flow process parameters. Using ultrasonic technique with coded signal and pulse compression method can achieve higher signal-to-noise ratio and resolution than using traditional single pulse signal while maintaining the same transmission power. In order to realize the accurate measurement of the void fraction in gas liquid two phase flow, the basic principle of two-phase flow test based on ultrasonic attenuation method is introduced. An ultrasonic testing system based on linear frequency modulation coded excitation and pulse compression signal was designed and implemented using FPGA. The size of the gas bubbles in liquid, and the void fraction of gas-liquid two phase flow were tested with the proposed system and method. The experiment results show that the coded excitation signal is sensitive to the size of the bubbles in gas liquid two phase flow; and using appropriate correction method, accurate measurement of the void fraction can be achieved. Within a certain range of the bubble size, the measurement accuracy can reach ±5%. This study lays a foundation for the ultrasonic testing technology based on the pulse compression with coded excitation signal in two phase flow process parameter measurement.
- 出版日期2014
- 单位天津大学
