Fluid flow velocity measurement using dual-ultrasonic transducer by means of simultaneously transit time method

摘要

An ultrasonic flowmeter based on transit time method (USM-TT) is often used to obtain high accuracy measurements of gas flow velocity. The working principle of an USM-TT is based on the measurements of two times of flight (TOF) of ultrasonic waves that propagate toward opposite direction. In particular, both TOFs are measured sequentially under the assumption that there exists no sudden change of flow velocity during the sampling period. When such an assumption is not fulfilled, the obtained velocity can not be assumed to be the true data. To overcome the above problem, we propose an alternative method, namely simultaneously transit time (STT), which is able to obtain both of TOFs for the same flow velocity by employing dual ultrasonic transducers that transmit and receive ultrasonic wave simultaneously. For experimental validation, two ultrasonic modules which have a transmitter and a receiver ultrasonic inside are utilized as ultrasonic transducer. In addition, microcontroller is employed for data acquisition and activating the ultrasonic devices. Based on the obtained experimental data, we found that the STT method effectively reduces the sampling period required in the conventional method up to almost 50%. Thus, because TOFs are obtained for the same flow velocity, the probability of the sudden change of flow velocity during the sampling period can be diminished.