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Experimental and Numerical Characterization of High Heat Fluxes During Transient Blackbody CalibrationsHigh heat fluxes are encountered in numerous applications, such as hypersonic vehicles in flight, fires, and engines, Calibration of heat flux gages may be performed in a dual cavity cylindrical blackbody resulting in a transient calibration environment. To characterize the transient heat fluxes. experiments were performed on a dual cavity cylindrical blackbody at nominal temperatures varying from 800 C to 1900 C in increments of 100 C. Based on experiments, the optimum heat flux sensor insertion location as measured from the center partition was determined. The pre-insertion steady state axial temperature profile is compared experimentally, numerically, and analytically. The effect of convection in the blackbody cavity during the insertion is calculated and found to be less than 2 per cent. Also, an empirical correlation for predicting the emissivity of the blackbody is included. Detailed transient thermal models have been developed to simulate the heat flux calibration process at two extreme fluxes. The high (1MW/sq m) and relatively low (70 kw/sq m) fluxes are reported in this article. The transient models show the effect of inserting a heat flux gage at room temperature on the thermal equilibrium of the blackbody at 1800 C and 800 C nominal temperatures, respectively. Also, heat flux sensor outputs are derived from computed sensor temperature distributions and compared to experimental results.
Document ID
20090009753
Acquisition Source
Armstrong Flight Research Center
Document Type
Conference Paper
Authors
Abdelmessih, Amanie N.
(Saint Martins' Univ. Lacey, WA, United States)
Horn, Thomas J.
(NASA Dryden Flight Research Center Edwards, CA, United States)
Date Acquired
August 24, 2013
Publication Date
August 20, 2008
Subject Category
Astronomy
Report/Patent Number
DFRC-785
Meeting Information
Meeting: ASME 2008 Summer Heat Transfer Conference
Location: Jacksonville, FL
Country: United States
Start Date: August 20, 2008
Sponsors: American Society of Mechanical Engineers
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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