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Onset of condensation effects as detected by total pressure probes in the Langley 0.3-meter transonic cryogenic tunnelTotal pressure probes mounted in the test section of a 0.3 meter transonic cryogenic tunnel were used to detect the onset of condensation effects for free stream Mach numbers of 0.50, 0.75, 0.85, and 0.95 and for total pressure between one and five atmospheres. The amount of supercooling was found to be about 3 K and suggests that condensation was occurring on pre-existing liquid nitrogen droplets resulting from incomplete evaporation of the liquid nitrogen injected to cool the tunnel. The liquid nitrogen injection process presently being used for the 0.3 m tunnel was found to result in a wide spectrum of droplet sizes being injected into the flow. Since the relatively larger droplets took much more time to evaporate than the more numerous smaller droplets, the larger ones reached the test section first as the tunnel operating temperature was reduced. However, condensation effects in the test section were not immediately measurable because there was not a sufficient number of the larger droplets to have an influence on the thermodynamics of the flow.
Document ID
19790018923
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Hall, R. M. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 3, 2013
Publication Date
May 1, 1979
Subject Category
Aerodynamics
Report/Patent Number
NASA-TM-80072
Accession Number
79N27094
Funding Number(s)
PROJECT: RTOP 505-06-43-08
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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