Modelling of Conditional Scalar Dissipation Rate in Turbulent Premixed Combustion

In turbulent premixed flames, for the mixing at a molecular level of reactants and products on the flame surface, it is crucial to sustain the combustion. This mixing phenomenon is featured by the scalar dissipation rate, which may be broadly defined as the rate of micro-mixing at small scales. This...

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Bibliographic Details
Main Authors: Shokri Amzin, Mariusz Domagała
Format: Article
Language:English
Published: MDPI AG 2021-02-01
Series:Computation
Subjects:
Online Access:https://www.mdpi.com/2079-3197/9/3/26
Description
Summary:In turbulent premixed flames, for the mixing at a molecular level of reactants and products on the flame surface, it is crucial to sustain the combustion. This mixing phenomenon is featured by the scalar dissipation rate, which may be broadly defined as the rate of micro-mixing at small scales. This term, which appears in many turbulent combustion methods, includes the Conditional Moment Closure (CMC) and the Probability Density Function (PDF), requires an accurate model. In this study, a mathematical closure for the conditional mean scalar dissipation rate, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo><</mo><msub><mi>N</mi><mi>c</mi></msub><mrow><mo>|</mo><mi>ζ</mi><mo>></mo></mrow></mrow></semantics></math></inline-formula>, in Reynolds, Averaged Navier–Stokes (RANS) context is proposed and tested against two different Direct Numerical Simulation (DNS) databases having different thermochemical and turbulence conditions. These databases consist of lean turbulent premixed V-flames of the CH4-air mixture and stoichiometric turbulent premixed flames of H2-air. The mathematical model has successfully predicted the peak and the typical profile of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo><</mo><msub><mi>N</mi><mi>c</mi></msub><mrow><mo>|</mo><mi>ζ</mi><mo>></mo></mrow><mtext> </mtext></mrow></semantics></math></inline-formula>with the sample space <i>ζ</i> and its prediction was consistent with an earlier study.
ISSN:2079-3197