A new method for researching the acoustic field of a gas ultrasonic flowmeter based on a Gaussian beam

Ultrasonic flowmeters are widely used in natural gas measurement. In order to achieve high accuracy, it is crucial to research the acoustic field. Therefore, a new method, which has the advantages of ray acoustics and wave acoustics, is proposed based on a Gaussian beam, through which the ultrasonic propagation trajectory, propagation time and sound pressure distribution can be analyzed. In order to apply a Gaussian beam in a gas ultrasonic flowmeter, flow information is added into its equation regarding three aspects: sound speed, angular frequency and sound pressure phase. In this paper, the feasibility of the improved Gaussian beam method has been verified by simulation and experiments. Firstly, under different uniform flow velocities, errors between the new method and COMSOL simulation are less than 1%. Secondly, compared with static experiments, when 125 kHz ultrasonic transducers are used, the errors between them are within  ±6%. When a microphone is used to measure the sound pressure of a 36.2 kHz transducer, errors between them are within  ±1.4%. Finally, sound pressure under different flow velocities has been verified through a dynamic experiment. The sound pressure and experimental voltage show the same trend of change. Verification shows that the improved Gaussian beam method can be used for acoustic field research in gas ultrasonic flowmeters. (paper)