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Type of Document	Dissertation
Author	Karagozian, Ann Renee
Author's Email Address	ark AT seas.ucla.edu
URN	etd-09132005-133501
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-09132005-133501
Title	An analytical study of diffusion flames in vortex structures
Degree	PhD
Option	Mechanical Engineering
Advisory Committee	Advisor Name Title Frank E. Marble Committee Chair Donald Cohen Committee Member Ed Zukoski Committee Member Eli Sternberg Committee Member Rolf Sabersky Committee Member
Keywords	none
Date of Defense	1982-05-17
Availability	unrestricted
Abstract NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The interaction of a laminar diffusion flame with two- and three-dimensional vortex structures is considered, in which the flame becomes severely distorted and is strained in its own plane. Fast chemical kinetics and unity stoichiometry are assumed. The resulting curved flame sheets are treated by applying the boundary layer approximation locally until neighboring flame sheets come sufficiently close to interact and consume the intervening reactant, thus creating a core of combustion products with external isolated flame sheets. The simplest example is the deformation of a diffusion flame by a viscous vortex of circulation [...]. For large [...] the radius of the core of combustion products increases in proportion to [...] , where D is the binary diffusivity, indicating the overall transport quantity to be [...]. The augmentation of reactant consumption due to the presence of the vortex is time-independent and behaves as [...]. The interaction of a laminar flame with a viscous vortex undergoing constant axial straining also is examined. The growth of the core radius has the similarity relation [...] indicating that the core eventually reaches a steady state size. The core continues to store products and the outer flame arms continue to consume reactants independently of time, however, due to axial extension. Hence there exist two different time scales governing the development of the flame: one associated with the flame-vortex interaction and one associated with the external strain rate. The effect of the release of heat (and subsequent density change) by the reaction on flame structure is examined by considering the interaction of a diffusion flame with a vortex undergoing a density change at the core. The decreased core density shifts the entire flowfleld radially outward, causing the burned core to be increased in size, while the radius of the unburned core decreases as [...], where [...] is the reactant density and p2 is the product density. The augmented consumption rate of the flame also is reduced, since the flame is being strained further from the viscous core and thus to a lesser extent.
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