CUED Publications database

Reaction zones and their structure in MILD combustion

Minamoto, Y and Swaminathan, N and Cant, RS and Leung, T (2014) Reaction zones and their structure in MILD combustion. Combustion Science and Technology, 186. pp. 1075-1096. ISSN 0010-2202

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Abstract

Three-dimensional direct numerical simulation (DNS) of turbulent combustion under moderate and intense low-oxygen dilution (MILD) conditions has been carried out inside a cuboid with inflow and outflow boundaries on the upstream and downstream faces, respectively. The initial and inflowing mixture and turbulence fields are constructed carefully to be representative of MILD conditions involving partially mixed pockets of unburned and burned gases. The combustion kinetics are modeled using a skeletal mechanism for methane-air combustion, including non-unity Lewis numbers for species and temperature-dependent transport properties. The DNS data is analyzed to study the MILD reaction zone structure and its behavior. The results show that the instantaneous reaction zones are convoluted and the degree of convolution increases with dilution and turbulence levels. Interactions of reaction zones occur frequently and are spread out in a large portion of the computational domain due to the mixture non-uniformity and high turbulence level. These interactions lead to local thickening of reaction zones yielding an appearance of distributed combustion despite the presence of local thin reaction zones. A canonical MILD flame element, called MIFE, is proposed, which represents the averaged mass fraction variation for major species reasonably well, although a fully representative canonical element needs to include the effect of reaction zone interactions and associated thickening effects on the mean reaction rate. Copyright © 2014 Taylor & Francis Group, LLC.

Item Type: Article
Uncontrolled Keywords: Direct numerical simulation (DNS) Flameless combustion MILD combustion Reaction zones
Subjects: UNSPECIFIED
Divisions: Div A > Energy
Depositing User: Cron Job
Date Deposited: 23 Jul 2014 15:45
Last Modified: 08 Dec 2014 02:10
DOI: 10.1080/00102202.2014.902814