Cavitating venturi performance at low inlet subcooling: Normal operation, overflow and recovery of overflow

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:100934

Ungar, E K; Dzenitis, J M ^[1]; Sifuentes, R T ^[2]

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1. NASA Johnson Space Center, Houston, TX (United States). Crew and Thermal Systems Division
2. McDonnell Douglas Aerospace, Houston, TX (United States). Thermal Control Systems Dept.

Cavitating venturis (CVs) were to have been used to passively control the flow of liquid ammonia to the evaporators in the Space Station Freedom (SSF) two-phase active thermal control system (ATCS). Because the head rise of the SSF ATCS pump was low to conserve electrical power, the inlet subcooling at the cavitating venturi would have been lower than is the case in normal CV applications. Testing at NASA/Johnson Space Center has shown that when cavitating venturis are operated at low values of inlet subcooling (on the order of 100 kPa or 15 psid), an overflow phenomenon can occur. Here the flow is liquid throughout the venturi and flows at a higher mass flow rate than the cavitation limit. Once overflow occurs, cavitation is reestablished only when the downstream pressure is decreased to a low value. Overflow test data were obtained for six cavitating venturis with throat diameters between 0.28 and 1.83 mm (0.011 and 0.072 in). Analysis of the test result showed that overflow could not be sustained beyond a critical value of the superheat pressure at the cavitating venturi throat. In the present work, the phenomenon of overflow is explored and its implications for cavitating venturis in general applications and for applications similar to SSF are discussed. Recommendations are made for predicting the mode of operation of a cavitating venturi at low values of the inlet subcooling.

• OSTI ID: 100934
• Report Number(s): CONF-940659--; ISBN 0-7918-1373-8
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CAVITATION
EXPERIMENTAL DATA
FLOW REGULATORS
HEAT EXCHANGERS
HEAT TRANSFER
OPERATION
PERFORMANCE
SPACE VEHICLES
TEMPERATURE CONTROL
TWO-PHASE FLOW
USES