A Study of Air-coupled Ultrasonic Flowmeter Using Beam Focusing

A non-contact flowrate measurement using the air-coupled ultrasound beam focusing technique is applied to the flowrate measurement in aluminum pipe. Flowrate measurement in the metal pipe by the air-coupled ultrasonic flowmeter has difficulty, because of the multipath of ultrasonic propagation. Bulk wave and guided wave are separated by experiment using metal pipes with and without an obstacle. The algorism for signal separation is built for the metal pipe measurement. Flowrate is calculated by the signal of bulk wave. Accordingly, the flowrate measurement on the aluminum pipe has been demonstrated, and the result shows the capability of measurement in metal pipes using air-coupled ultrasound.