Title page for ETD etd-08222012-002756


Type of Document Dissertation
Author Earp, Brian Edward
URN etd-08222012-002756
Title Convective Heat Flux Sensor Validation, Qualification and Integration in Test Articles
Degree PhD
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Schetz, Joseph A. Committee Chair
Devenport, William J. Committee Member
Lowe, Kevin Todd Committee Member
Rolling, August J. Committee Member
Wisniewski, Charles F. Committee Member
Keywords
  • Heat Flux
  • Thermal Instrumentation
  • Heat Transfer
  • Schmidt-Boelter
  • Inverse Heat Flux
Date of Defense 2012-08-08
Availability unrestricted
Abstract
The purpose of this study is to quantify the effects of heat flux sensor design and interaction with both test article material choice and geometry on heat flux measurements. It is the public domain component of a larger study documenting issues inherent in heat flux measurement. Direct and indirect heat flux measurement techniques were tested in three thermally diverse model materials at the same Mach 6 test condition, with a total pressure of 1200 psi and total temperature of 1188° R, and compared to the steady analytic Fay-Riddell solution for the stagnation heat flux on a hemisphere. A 1/8 in. fast response Schmidt-Boelter gage and a 1/16 in. Coaxial thermocouple mounted in ¾ in. diameter stainless steel, MACOR, and Graphite hemispheres were chosen as the test articles for this study. An inverse heat flux calculation was performed using the coaxial thermocouple temperature data for comparison with the Schmidt-Boelter gage. Before wind tunnel testing, the model/sensor combinations were tested in a radiative heat flux calibration rig at known static and dynamic heat fluxes from 1 to 20 BTU/ft2/s. During wind tunnel testing, the chosen conditions yielded stagnation point convective heat flux of 15-60 BTU/ft2/s, depending on the stagnation point wall temperature of the model. A computational fluid dynamic study with conjugate heat transfer was also undertaken to further study the complex mechanisms at work. The overall study yielded complex results that prove classic methodology for inverse heat flux calculation and direct heat flux measurement require more knowledge of the thermal environment than a simple match of material properties. Internal and external model geometry, spatial and temporal variations of the heat flux, and the level of thermal contact between the sensor and the test article can all result in a calculated or measured heat flux that is not correct even with a thermally matched sensor. The results of this study supported the conclusions of many previous studies but also examined the complex physics involved across heat flux measurement techniques using new tools, and some general guidance for heat flux sensor design and use, and suggestions for further research are provided.
Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Earp_BE_D_2012_f1.pdf 20.10 Mb 01:33:04 00:47:52 00:41:53 00:20:56 00:01:47

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.