Development of Ultrasonic Flowmeter Using Pulsed Doppler Method With Staggered Trigger Pulse

The ultrasonic pulsed Doppler method can be applied to obtain instantaneous velocity distribution along the ultrasonic beam path. This technique has many advantages, and it has been applied for measuring flow rate. However, the method has limitation about the measurable velocity and length. In order to overcome the limitation, a dealiasing method using staggered trigger pulse was applied for measuring velocity profile in a pipe. Furthermore, a multi-wave ultrasonic transducer was proposed for the measurement for improving the velocity measurement accuracy in the near-wall region. The applicability was examined for measuring velocity profile in a pipe with inner diameter of 200 mm. The velocity distributions were accurately obtained over the pipe by combining the velocity distributions at the basic frequency of 8 MHz for the near-wall region and 2 MHz for the region far from the transducer. As a result, it was confirmed that the flow rate measurement was improved by using the multi-wave method.