Numerical analysis of reaction-diffusion effects on species mixing rates in turbulent premixed methane-air combustion
Richardson, E.S., Sankaran, R., Grout, R.W. and Chen, J.H. (2010) Numerical analysis of reaction-diffusion effects on species mixing rates in turbulent premixed methane-air combustion. Combustion and Flame, 157, (3), 506-515. (doi:10.1016/j.combustflame.2009.11.007).
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The scalar mixing time scale, a key quantity in many turbulent combustion models, is investigated for reactive scalars in premixed combustion. Direct numerical simulations (DNS) of three-dimensional, turbulent Bunsen ﬂames with reduced methane-air chemistry have been analyzed in the thin reaction zones regime. Previous conclusions from single step chemistry DNS studies are conﬁrmed regarding the role of dilatation and turbulence-chemistry interactions on the progress variable dissipation rate. Compared to the progress variable, the mixing rates of intermediate species is found to be several times greater. The variation of species mixing rates are explained with reference to the structure of one-dimensional premixed laminar ﬂames. According to this analysis, mixing rates are governed by the strong gradients which are imposed by ﬂamelet structures at high Damk¨ohler numbers. This suggests a modeling approach to estimate the mixing rate of individual species which can be applied, for example, in transported probability density function simulations. Flame turbulence interactions which modify the ﬂamelet based representation are analyzed.
|Subjects:||T Technology > TA Engineering (General). Civil engineering (General)|
|Divisions:||University Structure - Pre August 2011 > School of Engineering Sciences
Faculty of Engineering and the Environment
|Date Deposited:||28 Jan 2011 09:06|
|Last Modified:||27 Mar 2014 19:20|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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