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Type: Journal article
Title: Reaction zone weakening effects under hot and diluted oxidant stream conditions
Author: Medwell, P.
Kalt, P.
Dally, B.
Citation: Combustion Science and Technology, 2009; 181(7):937-953
Publisher: Taylor & Francis Ltd
Issue Date: 2009
ISSN: 0010-2202
Statement of
Paul R. Medwell, Peter A. M. Kalt, and Bassam B. Dally
Abstract: This paper reports computational results, to complement experimental observations, on the turbulence-chemistry interaction of nonpremixed jet flames issuing into a heated and highly diluted oxidant stream. It is found experimentally that large-scale vortices and flame stretch can lead to spatial thinning and a decrease in OH concentration. This reduction in OH is described as a weakening of the reaction zone. Accompanying reaction zone weakening is also an increase in H2CO levels. The reduction in reaction rates is most noticeable at low oxidant stream O2 levels. The heated and low oxygen oxidant conditions typify those of moderate or intense low oxygen dilution (MILD) combustion. The computational results indicate that the effects of the low oxygen levels of MILD combustion leads to both a reduction in reaction rates and an increase in transport of O2 across the reaction zone. The relationship between the reaction rate and level of O2 permeation suggests that a form of partial premixing can occur under MILD combustion conditions. This partial premixing leads to the formation of flame intermediates, which contribute to the stabilization of the flames. The permeation effects are most pronounced at high strain rates, which are commonly encountered in practical MILD combustors.
Keywords: JHC burner; MILD combustion; Reaction zone weakening
RMID: 0020093961
DOI: 10.1080/00102200902904138
Appears in Collections:Mechanical Engineering publications
Environment Institute publications

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