Patent ID: 7389187

Claim:
An apparatus for measuring the flow velocity of a liquid flowing through a conduit, the apparatus comprising: an array of ultrasonic sensor pairs disposed at locations spaced along the length of the conduit in the direction of the flow of the liquid, each ultrasonic sensor pair having an ultrasonic transmitter and an ultrasonic receiver, each ultrasonic transmitter providing an ultrasonic signal having a transmission frequency of at least 5 megahertz, each ultrasonic receiver being responsive to the receipt of the ultrasonic signal for providing a respective sensor signal indicative of a parameter of an ultrasonic signal propagating through the liquid, wherein the array of ultrasonic sensor pairs comprising 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 ultrasonic sensor pairs; and a processor that performs a spatial-temporal transformation to define a convective ridge from the x-t domain to the k-ω domain in response to the sensor signals, and determines the slope of at least a portion of the convective ridge representing a concentration of disturbances that convect with the flow to determine the flow velocity of the liquid.