Application of Laser Doppler Velocity Instrumentation to the Measurement of Jet Turbulence

Approximately four years ago, NASA/Marshall Space Flight Center initiated a program to develop a laser Doppler heterodyne technique for the measurement of a local mean and fluctuating gas velocity with high spatial and temporal resolution. This paper contains design considerations and description of a laser Doppler velocity instrument capable of three component velocity measurements. This instrument has been applied to the measurement of subsonic jet turbulence. Comparison of these measurements with hot wire anemometer data obtained in the same facility indicate the laser Doppler velocity instrument is capable of making accurate turbulence measurements.