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EXPERIMENTAL INVESTIGATION OF THE PROPAGATION AND
EXTINCTION OF EDGE-FLAMES
by
David Baldwin Clayton
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements of the Degree
DOCTOR OF PHILOSOPHY
(MECHANICAL ENGINEERING)
August 2007
Copyright 2007 David Baldwin Clayton
Object Description
| Title | Experimental investigation of the propagation and extinction of edge-flames |
| Author | Clayton, David Baldwin |
| Author email | davidcla@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Mechanical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2007-06-28 |
| Date submitted | 2007 |
| Restricted until | Unrestricted |
| Date published | 2007-07-17 |
| Advisor (committee chair) | Ronney, Paul |
| Advisor (committee member) |
Egolfopoulos, Fokion Lee, C. Ted |
| Abstract | Propagation rates (Uedge) of various hydrocarbon premixed edge-flames are directly measured as a function of global strain rate, mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive Uedge) and retreating (negative Uedge) edge-flames can be studied as they propagate across the long dimension of the burner. Results are presented for twin and single premixed edge-flames in terms of the effects of a nondimensional strain rate and nondimensional heat loss on a scaled propagation rate. Twin edge-flames exhibited two extinction limits, corresponding to a high-strain limit induced by strain and a low-strain heat loss induced limit. A similar low-strain limit is identified for single edge-flames but at high-strain the flames break apart due to an apparent strain induced instability rather than extinction. Propagation rates clearly show a strong dependence on Le and close-up images of the premixed edge-flames show that high (low) Le lead to weaker (stronger) edge-flame propagation. Overall, experimental findings agree closely with theoretical predictions. Additionally, the effects of diffusive-thermal instability on mixtures with very low Le in the counterflow strained configuration are examined. Stability maps and propagation rates for twin premixed, single premixed, and nonpremixed H2-air flames indicate the importance of heat losses to the burner at low strain and the dependence of flame propagation on global strain rate in relation to the burner configuration. As predicted, low Le flames in the counterflow configuration form individual and connected tubes as a means of existing beyond typical extinction strain rates. The tubes transition into wrinkled flames and then into planar flame structures as strain decreases. Propagation rates for the lean H2 flames generally increase with increasing strain and are not affected by the instability mode and resulting the flame shape. |
| Keyword | edge-flame; slot-jet; short-length; hydrocarbon; hydrogen |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m624 |
| Rights | Clayton, David Baldwin |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Clayton-20070717 |
| Archival file | uscthesesreloadpub_Volume44/etd-Clayton-20070717.pdf |
Description
| Title | Page 1 |
| Full text | EXPERIMENTAL INVESTIGATION OF THE PROPAGATION AND EXTINCTION OF EDGE-FLAMES by David Baldwin Clayton A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements of the Degree DOCTOR OF PHILOSOPHY (MECHANICAL ENGINEERING) August 2007 Copyright 2007 David Baldwin Clayton |
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