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High-resolution heat-transfer-coefficient maps applicable to compound-curve surfaces using liquid crystals in a transient wind tunnelTests were performed in a transient heat transfer tunnel in which the model under test was preheated prior to allowing room temperature air to be suddenly drawn over the model. The resulting movement of isothermal contours on the model is revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record is obtained of a temperature and time data pair for all points on the model during a single test. Experiments on a duct model are reported in which the model was preheated using a hot air stream. A manner in which initial model temperature nonuniformities could be taken into account was investigated. The duct model was also tested with a steady-state measurement technique and results were compared with the transient measurements, but recognizing that differences existed between the upstream thermal boundary conditions. The steady-state and transient measurements were shown to be consistent with predicted values. The main advantage of this transient heat transfer technique using liquid crystals is that since the test model need not be actively heated, high-resolution measurements on surfaces with complex shapes may be obtained.
Document ID
19890000875
Document Type
Technical Memorandum (TM)
Authors
Jones, Terry V. (Oxford Univ. Cleveland, OH, United States)
Hippensteele, Steven A. (NASA Lewis Research Center)
Date Acquired
September 5, 2013
Publication Date
August 1, 1988
Subject Category
FLUID MECHANICS AND HEAT TRANSFER
Report/Patent Number
E-3269
NASA-TM-89855
NAS 1.15:89855
Meeting Information
ASME National Heat Transfer Conference(Pittsburgh, PA)
Funding Number(s)
PROJECT: RTOP 505-62-21
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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