Scholarly
    Communications Project


Document Type:Dissertation
Name:Don Gregory Walker Jr.
Email address:greg.walker@vt.edu
URN:1997/00483
Title:Estimation of Unsteady Nonuniform Heating Rates from Surface Temperature Measurements
Degree:Doctor of Philosophy
Department:Mechanical Engineering
Committee Chair: Dr. Elaine P. Scott
Chair's email:scottep@vt.edu
Committee Members:Dr. Tom Diller
Dr. Tao Lin
Dr. Wing Ng
Dr. Brian Vick
Keywords:inverse heat conduction, shock interactions
Date of defense:November 25, 1997
Availability:Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.

Abstract:

Shock wave interactions such as those that occur during atmospheric re-entry, can produce extreme thermal loads on aerospace structures. These interactions are reproduced experimentally in hypersonic wind tunnels to study how the flow structures relate to the deleterious heat fluxes. In these studies, localized fluid jets created by shock interactions impinge on a test cylinder, where the temperature due to the heat flux is measured. These measurements are used to estimate the heat flux on the surface as a result of the shock interactions. The nature of the incident flux usually involves dynamic transients and severe nonuniformities. Finding this boundary flux from discrete unsteady temperature measurements is characterized by instabilities in the solution. The purpose of this work is to evaluate existing methodologies for the determination of the unsteady heat flux and to introduce a new approach based on an inverse technique. The performance of these methods was measured first in terms of accuracy and their ability to handle inherently ``unstable'' or highly dynamic data such as step fluxes and high frequency oscillating fluxes. Then the method was expanded to estimate unsteady and nonuniform heat fluxes. The inverse methods proved to be the most accurate and stable of the methods examined, with the proposed method being preferable.

List of Attached Files

shock_etd.240.avi shock_etd.480.avi walketd.pdf

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