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Maximum Expected Wall Heat Flux and Maximum Pressure After Sudden Loss of Vacuum Insulation on the Stratospheric Observatory for Infrared Astronomy (SOFIA) Liquid Helium (LHe) DewarsThe aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared observation experiments. The experiments carry sensors cooled to liquid helium (LHe) temperatures. A question arose regarding the heat input and peak pressure that would result from a sudden loss of the dewar vacuum insulation. Owing to concerns about the adequacy of dewar pressure relief in the event of a sudden loss of the dewar vacuum insulation, the SOFIA Program engaged the NASA Engineering and Safety Center (NESC). This report summarizes and assesses the experiments that have been performed to measure the heat flux into LHe dewars following a sudden vacuum insulation failure, describes the physical limits of heat input to the dewar, and provides an NESC recommendation for the wall heat flux that should be used to assess the sudden loss of vacuum insulation case. This report also assesses the methodology used by the SOFIA Program to predict the maximum pressure that would occur following a loss of vacuum event.
Document ID
20140013266
Acquisition Source
Langley Research Center
Document Type
Technical Memorandum (TM)
Authors
Ungar, Eugene K.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
October 29, 2014
Publication Date
October 1, 2014
Subject Category
Engineering (General)
Report/Patent Number
NESC-RP-13-00911
NF1676L-20011
NASA/TM-2014-218540
L-20483
Funding Number(s)
WBS: WBS 869021.03.07.01.01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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