A Thin-Film Probe for the Measurement of a Three-Dimensional Velocity Vector

A new hot-film probe intended for the measurement of velocity, in magnitude and direction, in three-dimensional water flow is described. Using boundary layer theory, the response of the probe to steady velocity is derived and is found to agree closely with calibrations. The probe has proved to be robust and durable; it produced reliable and repeatable calibrations when towed in a water tank. The method of data acquisition and the technique used for computing the velocity vector are reported.