3-D velocity field measurement using multiple ultrasonic plane detections and high-order correlation analysis.

A method of measuring the three-dimensional velocity field of laminarlike flow noninvasively by combining multiple ultrasonic plane detectors and a corresponding level of high-order cross-correlation analysis is presented. It is assumed that the velocity field consists of a set of straight line streams and that each stream contains random fluctuations that serve to tag the location of each stream as it passes through the detectors. The time delays of each stream between the various pairs of plane detectors are estimated by using high-order cross-correlation analysis of the detected signals. From the estimated time delays the stream velocities and their positions are measured and the three-dimensional velocity field pattern is reconstructed. To confirm the usefulness of this method, an actual measurement system has been constructed in a water tank, and experiments using controlled flow through thin tubes have been carried out. The details of the system and the results are shown.