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Modelling of the curvature term in the Flame surface density transport equation: a direct numerical simulations based analysis

Lookup NU author(s): Mohit Katragadda, Dr Sean Malkeson, Professor Nilanjan ChakrabortyORCiD

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Abstract

A simple chemistry based three-dimensional Direct Numerical Simulations (DNS) database of freely propagating statistically planar turbulent premixed flames with a range of different values of Karlovitz number Ka, turbulent Reynolds number Re-t, heat release parameter tau and global Lewis number Le has been used for the modelling of the curvature term of the generalised Flame Surface Density (FSD) transport equation in the context of Reynolds Averaged Navier Stokes (RANS) simulations. The curvature term has been split into the contributions arising due to the reaction and normal diffusion components of displacement speed (i.e. T-1) and the term arising due to the tangential diffusion component of displacement speed (i.e. T-2). Subsequently, the sub-terms (i.e. T-1 and T-2) of the curvature contribution to the FSD transport have been split into the closed (i.e. T-1r and T-2r) and unclosed (i.e. T-1ur, and T-2ur) components. It has been found that T-2 remains deterministically negative throughout the flame brush. However, the qualitative behaviour of T-1 changes significantly depending upon the values of Ka, Re-t and Le. Detailed physical explanations have been provided for the observed behaviours of the components of the curvature term. Moreover, it has been observed that the closed contributions of T-1 and T-2 (i.e. T-1r and T-2r) remains negligible in comparison to the unclosed contributions (i.e. T-1ur and T-2ur). Suitable model expressions have been identified for T-1ur and T-2ur in the context of RANS simulations, which are shown to perform satisfactorily in all cases considered in the current analysis, accounting for the variations in Ka, Re-t, tau and Le.

Publication metadata

Author(s): Katragadda M, Malkeson SP, Chakraborty N

Publication type: Article

Publication status: Published

Journal: International Journal of Spray and Combustion Dynamics

Year: 2014

Volume: 6

Issue: 2

Pages: 163-198

Print publication date: 01/06/2014

Online publication date: 25/06/2014

Acceptance date: 14/01/2013

ISSN (print): 1756-8277

ISSN (electronic): 1756-8285

Publisher: Multi-Science Publishing Co. Ltd

URL: http://dx.doi.org/10.1260/1756-8277.6.2.163

DOI: 10.1260/1756-8277.6.2.163

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