Modelling of microgravity ignition phenomena

The structure and stability of flame balls and the characteristics of the outwardly propagating spherical flames of sub-limit mixtures are studied both analytically and numerically in the context of an asymptotic analysis in which θ\to\infty, and (1 $-$ Le) = O(1/θ), where θ is the activation energy and Le is Lewis number. For flame balls, the heat loss mechanism necessary for stable solutions is the radiation from burnt gas. If heat loss is less than quenching value, there are two stationary solutions, but the small branch solution is always unstable to the one dimensional disturbances regardless of Lewis number when Le $\leq$ 1. And the large branch solution is stable within a certain range of heat loss, if Lewis number is less than the critical Lewis number Le$\sb{\rm c}$ (Le $<$ Le$\sb{\rm c}\/<$ 1). The flame balls with sufficiently large radius are always unstable to three dimensional disturbances, independent of Le. These results, therefore, reveal that flame balls can only be possible if Le $<$ Le$\sb{\rm c}$ where Le$\sb{\rm c}$ is identified very close to unity. The three dimensional stability is not Lewis number but near field heat losses driven.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Lee, Changjin

Contributors dc:contributor

• Buckmaster, John

• Engineering, Aerospace
• Engineering, Mechanical

Statement dc:rights

• Copyright 1992 Lee, Changjin

Language dc:language

eng

Identifier

AAI9236514
(UMI)AAI9236514

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21616