Abstract: The meter has a housing with an inlet and an outlet. The housing is divided between the inlet and the outlet by a partition wall through which a measuring tube with a rectangular cross-section passes. Gas flows through the measuring tube, through which ultrasonic pulses are simultaneously transmitted by transducers disposed on the end walls. The flow rate of the gas is determined from the difference in the time of flight of the bidirectional sound pulses. The gas is directed into the measuring tube through two guidance ducts which run along both longitudinal sides of the measuring tube. Said guidance ducts are also rectangular in cross-section and each contain a flow rectifier.

Abstract: An ultrasonic transducer array, and a method for manufacturing it, having a plurality of transducer elements aligned along an array axis in an imaging plane. Each transducer element includes a piezoelectric layer and one or more acoustic matching layers. The piezoelectric layer has a concave front surface overlayed by a front electrode and a rear surface overlayed by a rear electrode. The shape of each transducer element is selected such that it is mechanically focused into the imaging plane. A backing support holds the plurality of transducer elements in a predetermined relationship along the array axis such that each element is mechanically focused in the imaging plane.