Patent ID: 7752918

Claim:
A method for measuring at least one parameter of a fluid flowing through an internal passage of an elongated body, which internal passage is disposed between a first wall and a second wall, and the first wall and the second wall each include an interior surface and an exterior surface, the method comprising: providing an array of at least two ultrasonic sensor units, each sensor unit including an ultrasonic transmitter mounted on the exterior surface of the first wall and an ultrasonic receiver located on the exterior surface of the second wall and substantially aligned with the transmitter; wherein each sensor unit further includes a feedback ultrasonic receiver located on the exterior surface of the first wall, and each feedback receiver is operable to receive ultrasonic signals transmitted from the transmitter and reflected within the first wall; operating the ultrasonic transmitters to transmit ultrasonic signals through the first wall, at one or more frequencies substantially coincident with at least one frequency at which the transmitted ultrasonic signals resonate within the first wall, in a manner that increases a signal-to-noise ratio of the ultrasonic signals by using resonance of the ultrasonic signals within the first wall to increase the amplitude of the ultrasonic signals traveling through the first wall, and thereby increase the amplitude of the ultrasonic signals transmitted into the internal passage; receiving the ultrasonic signals with the ultrasonic receivers; and processing the received ultrasonic signals to measure the at least one parameter of fluid flow within the internal passage.