MEASUREMENT OF THE TURBULENCE WITH THE LASER-DOPPLER ANEMOMETER.

The laser-Doppler anemometer is an instrument for research on fluid flows that has the potential of allowing local time-resolved measurements of fluid velocity without disturbing the fluid phenomenon under investigation. However, as in the case of its main competitor in the field, the hot-wire anemometer, the application of the LDA to turbulence measurements is not trivial, and the problems (and challenges) facing the experimenter grow with increasing levels of turbulent fluctuations. This paper reviews the status of turbulence measurements with the LDA and outlines the achievements of the past few years and some of the remaining problems. The article deals with only those methods allowing time-resolved measurements of the velocity, and thus the authors do not treat such signal-processing methods as spectrum analysis of the Doppler signal or time-averaged photon correlation.