A sensor for high-quality two-phase flow

A sensor for high-quality two-phase flow

Delil, A.A.M.

National Aerospace Laboratory NLR

1988-04-15

Two-phase heat transport systems are currently considered for the thermal management of large power spacecraft. The monitoring of the quality of the two-phase mixture at various locations in the system is a valuable, possibly indispensable, part of the control system needed to properly operate such a two-phase loop. Concepts for quality monitoring have been reviewed: few turn out to be suitable tor spacecraft. Promising concepts, based on dielectric permittivity (capacitance), sonic velocity and index of refraction, have been quantitatively analysed. Applicability, advantages, restrictions and hardware aspects have been discussed. As a result of the aforementioned analysis NLR started the development of a dedicated quality sensor, based on the axial capacitance principle. Its feasibility has been theoretically demonstrated. Preliminary tests - with liquid layer simulating plastic sheets and with annular air/liquid flow - experimentally confirm the feasibility, not only as vapour quality sensor but also as wetting (liquid layer thickness) sensor, for freons, ammonia, water, toluene, etc. Experiments in a two-phase freon test loop show the sensor to be such an accurate, fastly responding, sensitive instrument, that it recently has been accepted for inclusion in the two-phase heat transport system developed by the European Space Agency. A review of the development work and the test results is presented. Recommendations for future work and applications foreseen are indicated. Presented in the Thermophysics and Thermochemistry Session of the 16th International symposium on Space Technology and Science, May 22-27, 1988, Sapporo, Japan

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Nationaal Lucht- en Ruimtevaartlaboratorium

Campus only

NLR MP 88025 U

Aerospace Engineering Reports

report

(c) 1988 National Aerospace Laboratory NLR