Measurement of turbulence by laser homodyne technique

A method of measuring turbulence by means of the laser homodyne technique without relying upon time-sequential data, which ordinary methods use in obtaining information on turbulence, is studied. The principle of this method is to detect relative fluid motions of turbulence by receiving a beat of light scattered from each pair of tracer particles. A photoelectron correlation method is used to process the photomultiplier signal to yield statistical average of the light beat over the pairs in the measuring volume. A set of autocorrelograms that are gained for different dimensions of the measuring volume leads to a relation between the fluctuating velocity and the dimension, which is fitted to the theoretical one to yield turbulence intensity and integral scale. A verification of the proposed method is made by comparing the results with hot-wire anemometer results. A discussion is made of several factors that affect the accuracy.