A new type of ultrasonic gas flowmeter with multi-tracks

In general, two major factors effect on the measurement precision of ultrasonic transit-time gas flowmeter: the calculations of gas velocity distribution in the pipe and the measurements of the transit time of ultrasonic transmitting from one transducer to another. In this paper, considering the affect factors, a new design of ultrasonic gas flow meter is proposed, which is operated by a master slave control based on a single board computer and a MCU. In order to calculate the velocity distribution in the whole pipe, the multi-tracks (5 tracks) are used to measure the transit times of ultrasonic waves between each pair of the corresponding transducers located at five different profiles of the pipe, by which the gas velocity near the pipe wall can be described more accurately, especially at a low gas velocity. Meanwhile, the ultrasonic beam deflection altered with the change of the gas velocity is modified by software in order to improve the accuracy of time interval. In addition, the peak value transmission circuit is employed to optimize the self-adaptive ability of the system, which can also raise the SNR and reduce the measurement error resulting from the ultrasonic beam deflection. At last, this work proposed a new algorithm for flow calculation based on the improvements mentioned above. These results show that the method has better accuracy, rangeability, stability and repeatability compared to traditional ones.