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Hydrodynamic Dryout in Two-Phase Flows: Observations of Low Bond Number SystemsDryout occurs readily in certain slug and annular two-phase flows for systems that exhibit partial wetting. The mechanism for the ultimate rupture of the film is attributed to van der Waals forces, but the pace towards rupture is quickened by the surface tension instability (Rayleigh-type) of the annular film left by the advancing slug and by the many perturbations of the free surface present in the Re(sub g) approximately 0(10(exp 3)), Re(sub l) approximately 0(10(exp 4)), and Ca approximately 0(10(exp -1) flows. Results from low-gravity experiments using three different test fluids are presented and discussed. For the range of tests conducted, the effect of increasing viscosity is shown to eliminate the film rupture while the decrease of surface tension via a surfactant additive is shown to dramatically enhance it. Laboratory measurements using capillary tubes are presented which reveal the sensitivity of the dryout phenomena to particulate and surfactant contamination. Rom such observations, dryout due to the hydrodynamic-van der Waals instability can be expected in a certain range of flow parameters in the absence of heat transfer. The addition of heat transfer may only exacerbate the problem by producing thermal transport lines replete with "hot spots." A caution to this effect is issued to future space systems designers concerning the use of partially wetting working fluids.
Document ID
19990032168
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Weislogel, Mark M.
(NASA Lewis Research Center Cleveland, OH United States)
McQuillen, John B.
(NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Subject Category
Fluid Mechanics And Heat Transfer
Meeting Information
Meeting: Space Technology and Information Forum: Commercial Development of Space
Location: Albuquerque, NM
Country: United States
Start Date: January 25, 1998
End Date: January 29, 1998
Funding Number(s)
PROJECT: RTOP 963-25-OH
Distribution Limits
Public
Copyright
Other

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