New Velocity Measuring Technique Using Dual-Scatter Laser Doppler Shift
Final rept. Jul 1969-Jul 1970
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN
Pagination or Media Count:
Conventional laser Doppler velocimeters LDV detect velocity by heterodyning scattered, Doppler shifted radiation with unscattered, reference radiation. A new dual-scatter LDV technique is described which simultaneously illuminates a moving scatterer from two different directions and heterodynes the two superimposed radiations simultaneously scattered in a common direction. Significant advantages are derived from the fact that the Doppler difference frequency thus obtained is independent of the scattered direction, permitting unusually large quantities of scattering radiation to be collected without adversely affecting the signal frequency dispersion these advantages include enhanced signal-to-noise performance and a capability to measure fluid flows with unusually high velocity andor low seed density. System performance, experimental verifications, and typical system designs are presented.
- Test Facilities, Equipment and Methods
- Fluid Mechanics