Project Title:

Hybrid Measurement of Two-Phase Flows

09.04-3200A
Hybrid Measurement of Two-Phase Flows
Foster-Miller, Inc.
350 Second Avenue
Waltham, MA 02254
Wayne S. Hill  (617-890-3200)
JSC -- NAS9-17941

Abstract:

	 Monitoring and control of spacecraft thermal management systems involving two-phase
flows requires the determination of the mass flow and quality at various places in
the system. Short of separating the fluid phases, the only means of determining both
the mass flow rate and flow quality in a two-phase flow is to make simultaneous,
complementary measurements and to process the readings using an appropriate analysis.
This technique, called hybrid flow measurement, has been of limited applicability
in the past because of the limited turndown achievable with most volume flow meters.
The bearingless flowmeter is a volumetric flowmeter that appears to offer the desired
turndown performance.
	In Phase I, a bearingless flowmeter was examined as a two-phase flowmeter in a preliminary
test program. This work demonstrated the feasibility of the program concept: employing
simultaneous, complementary measurements to determine the mass flow and quality.
However, the pulse output data for the bearingless flowmeter displayed a bifurcation
that indicated the presence of unstable rotor motions resulting in a low pulse output.
This instability was not found in the liquid flow data or in some of the two-phase
flow data, but occurred consistently in the gas flow data. Through an analysis of
the design, this instability was traced to the fact that the bearingless flowmeter
is a poor gas bearing. An alternative design approach was identified that should
provide stable rotor motion in liquid, two-phase, and gas flows with an acceptable
overall pressure drop.

Potential Commercial Application:

Potential Commercial Application: A two-phase flowmeter could see widespread application
in the nuclear, medical, and chemical process industries.