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Modeling and Calibration of Fast-Response Coaxial Heat Flux Gages

Marineau, Eric C. and Hornung, Hans G. (2009) Modeling and Calibration of Fast-Response Coaxial Heat Flux Gages. In: 47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition. American Institute of Aeronautics and Astronautics , Reston, VA, Art. No. 2009-737. ISBN 978-1-60086-973-0. https://resolver.caltech.edu/CaltechAUTHORS:20200117-095543698

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Abstract

This research focuses on the modeling and calibration of fast response coaxial heat flux gages. Simulations of the heat conduction inside the gage using Gasp solver show, that the response is sensitive to geometry of the junction which sits on epoxy. The epoxy acts as an insulator creating a local overheating that increases with the junction aspect ratio and the step height between the inner and outer electrodes and decreases when epoxy is present next to the step. The increase of the overheating with the junction aspect ratio is due to the thermal insulation of the epoxy layer located under the junction used to electrically insulate the two electrodes of the thermocouple. When the junction protrudes significantly above the surface (about 10 microns), the heat transfer is enhanced from the larger surface area whereas, the lateral conduction around the epoxy layer decreases, which further contributes to the junction overheating. To assess those effects, a calibration method using a reflected shock in argon is developed and experiments are performed in the T5 free-piston shock tunnel which is used as a shock tube by replacing the nozzle throat insert with a closed end-wall insert. Five gages are simultaneously calibrated at a high heat flux for 30 microseconds. For microsecond time scales, it is found that the effective value of the thermal product, √pck, is approximately 30% lower than the average of chromel and constantan. The standard deviation of 10% among the five gages indicates that the gage-to-gage variation of the junction geometry is relatively small as the temperature is greatly sensitive to the geometry on microsecond time scales.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.2514/6.2009-737DOIArticle
ORCID:
AuthorORCID
Hornung, Hans G.0000-0002-4903-8419
Additional Information:© 2009 by the American Institute of Aeronautics and Astronautics, Inc. Published online: 15 Jun 2012.
Group:GALCIT
Other Numbering System:
Other Numbering System NameOther Numbering System ID
AIAA Paper2009-737
Record Number:CaltechAUTHORS:20200117-095543698
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200117-095543698
Official Citation:Modeling and Calibration of Fast-Response Coaxial Heat Flux Gages. Eric Marineau and Hans Hornung. 47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition. January 2009; doi: 10.2514/6.2009-737
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100786
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Jan 2020 19:00
Last Modified:17 Jan 2020 19:00

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