Effect of carrier gas pressure on condensation in a supersonic nozzle

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Physics of Fluids; (United States)

DOI:https://doi.org/10.1063/1.868107· OSTI ID:7104207

Wyslouzil, B E; Wilemski, G; Beals, M G; Frish, M B ^[1]

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1. Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States)

Supersonic nozzle experiments were performed with a fixed water or ethanol vapor pressure and varying amounts of nitrogen to test the hypothesis that carrier gas pressure affects the onset of condensation. Such an effect might occur if nonisothermal nucleation were important under conditions of excess carrier gas in the atmospheric pressure range, as has been suggested by Ford and Clement [J. Phys. A [bold 22], 4007 (1989)]. Although a small increase was observed in the condensation onset temperature as the stagnation pressure was reduced from 3 to 0.5 atm, these changes cannot be attributed to any nonisothermal effects. The pulsed nozzle experiments also exhibited two interesting anomalies: (1) the density profiles for the water and ethanol mixtures were shifted in opposite directions from the dry N[sub 2] profile; (2) a long transient period was required before the nozzle showed good pulse-to-pulse repeatability for condensible vapor mixtures. To theoretically simulate the observed onset behavior, calculations of nucleation and droplet growth in the nozzle were performed that took into account two principal effects of varying the carrier gas pressure: (1) the change in nozzle shape due to boundary layer effects and (2) the variation in the heat capacity of the flowing gas. Energy transfer limitations were neglected in calculating the nucleation rates. The trend of the calculated results matched that of the experimental results very well. Thus, heat capacity and boundary layer effects are sufficient to explain the experimental onset behavior without invoking energy transfer limited nucleation. The conclusions about the rate of nucleation are consistent with those obtained recently using an expansion cloud chamber, but are at odds with results from thermal diffusion cloud chamber measurements.

• DOE Contract Number: AC02-84ER13154; FG02-92ER14257
• OSTI ID: 7104207
• Journal Information: Physics of Fluids; (United States), Journal Name: Physics of Fluids; (United States) Vol. 6:8; ISSN PHFLE6; ISSN 1070-6631
• Country of Publication: United States
• Language: English

Related Subjects

661300* -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALCOHOLS
CLOUD CHAMBERS
CONDENSATION NUCLEI
DROPLETS
ELEMENTS
ETHANOL
EXPANSION CHAMBERS
FLUID FLOW
GAS TRACK DETECTORS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
MEASURING INSTRUMENTS
NITROGEN
NONMETALS
NOZZLES
NUCLEATION
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PARTICLES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RADIATION DETECTORS
SUPERSONIC FLOW
THERMODYNAMIC PROPERTIES
VAPOR PRESSURE
WATER