Project Title:

Laser Doppler Velocimeter for Flow Rate Measurement in Thermal Control Fluid Systems

13.06-1512
Laser Doppler Velocimeter for Flow Rate
	Measurement in Thermal Control Fluid Systems
Ophir Corporation
3190 S. Wadsworth Blvd., Suite 100
Lakewood, CO 80277
Gregory J. Fetzer  (303-976-1512)
MSFC -- NAS8-37631

Abstract:

	 A non-intrusive flow measurement system is required for small-diameter, low-flow-rate,
and low-pressure-differential fluid systems for thermal control functions. This innovation
utilizes a continuous-wave, diode-based laser Doppler velocimeter (LDV) which captures
scattered radiation from minute (10.0 m) inert particles suspended in the flow medium.
The particulates may occur naturally as impurities in the coolant or may be mixed
in the coolant at the time of a system fill. Theoretical calculations indicate that
the system will provide flow measurement capabilities at flow rates as low as 10.0
lbs/hr for Freon-12 and deionized water cooling systems in pipe diameters of 1/8
to 1/2 inch with accuracies of 0.5 percent or better.
	The prototype device tested in Phase I was an optical heterodyne system which measures
a Doppler-induced frequency shift. Results of these tests indicate that the LDV concept
is both feasible and practical for flow measurement in small diameter tubing. It
is particularly well-suited to low-pressure-differential systems designed for laminar
flow and applies as well for turbulent flows. The use of a diode laser allows for
an inexpensive, compact, rugged device which exceeds the performance objectives of
this project.

Potential Commercial Application:

Potential Commercial Application: An accurate flow measurement system for small-volume,
low-differential-pressure systems has applications in process control, fuel-flow
control, bioengineering, and other areas.