Abstract: A device for performing ultrasonic measurements on liquid flowing within a duct includes a pair of transducers communicating along an acoustic path within the duct. The acoustic path includes at least one midradius chord of the duct, the projection of that chord on a plane parallel thereto and including the duct axis being tilted with respect to the axis.

Abstract: In the acoustic flowmeter apparatus disclosed herein, repetitively gated bursts of relatively high frequency acoustic energy are transmitted between upstream and downstream transducers in a conduit in which flow is to be measured, the transmission being alternately in an upstream and a downstream direction. The received signals are amplified and subjected to narrow band filtering so as to extract an essentially continuous component at the high frequency, preserving phase information. By measuring the relative phase shifts of the upstream and downstream transmissions, a measurement proportional to flow rate is obtained. In the preferred embodiment, the sum of the transit times is measured by measuring the phase shifts of the principal repetition frequency modulation component of the received signals.

Abstract: A device for performing ultrasonic measurements on liquid flowing within a conduit having walls of relatively high acoustic impedance material. The conduit is split into two separate segments with the emitting transducer in one segment and a receiving transducer in the other segment. The space between segments is filled with a sealant material having relatively low acoustic impedance characteristics to provide an acoustic mismatch and hence attenuation to ultrasonic energy traveling through the conduit wall from the transmitter to the receiver. Because of the separation between segments ready access is provided to the internal walls of the conduit, allowing transducer configurations to be employed, which configurations require machining or assembly to be performed on the interior walls.