Signal analysis of ultrasonic flowmeter based on gas acoustic relaxation

Abstract In this essay, a method for analyzing echo signals in ultrasonic gas flow meters based on gas acoustic relaxation is proposed. It was found that acoustic relaxation absorption is the main factor affecting the attenuation of ultrasonic signals, especially when using ultrasound at 200kHz for flow measurements. By simulating and analyzing the acoustic relaxation time, the relaxation frequency, and the acoustic absorption coefficient under different conditions, the match between the gas relaxation frequency and the acoustic wave frequency was found to be the main factor affecting the acoustic absorption coefficient. The influence laws of the changes of temperature, pressure, and gas components on the acoustic pressure attenuation characteristics are revealed. Experiments were carried out with temperature and pressure as variables. It was found that the deviation of the simulation results from the change rule of the actual effect was within 5%, which provided a reliable theoretical foundation for the adaptive adjustment of the threshold voltage of the ultrasonic gas flowmeter.