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Published June 2017 | Supplemental Material
Journal Article Open

Effects of dissipation rate and diffusion rate of the progress variable on local fuel burning rate in premixed turbulent flames

Abstract

The validity of the premixed flamelet equations and the dependence of the fuel burning rate on the parameters involved in these equations have been investigated using a large series of direct numerical simulations of turbulent premixed flames in the thin reaction zones (TRZ) and the distributed reaction zones (DRZ) regimes. Methane, toluene, n-heptane, and iso-octane fuels were considered over a wide range of unburnt conditions and turbulence characteristics. Flames with unity and non-unity Lewis numbers were investigated separately to isolate turbulence-chemistry interaction from differential diffusion effects. In both cases, the flamelet equations, which rely on the assumption of a thin reaction zone, are locally valid throughout the TRZ regime, more precisely up to a Karlovitz number at the reaction zone of 10 (based on the definition used in this paper). Consistent with this result, in the unity Lewis number limit, the fuel burning rate is strongly correlated with the dissipation rate of the progress variable, the only parameter in the flamelet equations. In the non-unity Lewis number case, the burning rate is a strong function of both the dissipation rate and the diffusion rate, both of which are parameters in the flamelet equations. In particular, the correlation with these parameters is significantly better than with curvature or tangential strain rate.

Additional Information

© 2017 The Combustion Institute. Published by Elsevier Inc. Received 14 September 2016, Revised 5 December 2016, Accepted 20 February 2017, Available online 12 March 2017. The authors gratefully acknowledge funding from the Air Force Office of Scientific Research (Award FA9550-12-1-0144) under the supervision of Dr. Chiping Li, the Fonds de recherche du Québec - Nature et Technologies (Postdoctoral fellowship D3), the Academic Computer Center in Gdańsk (CI TASK), the Social Found of the European Union (Scholarship for Visiting Professor at the Warsaw University of Technology), the U.S. Department of Energy-Basic Energy Sciences (DE-SC006591) under the supervision of Dr. Wade Sisk, and the Natural Sciences and Engineering Research Council of Canada (NSERC Postgraduate Scholarship D). The authors would also like to thank Dr. Simon Lapointe for his help in processing the data and Dr. Ramanan Sankaran, Dr. Evatt R. Hawkes, Dr. Chun Sang Yoo, Dr. Jacqueline H. Chen, along with Dr. Hemanth Kolla who shared with the authors the DNS data of Ref. [39].

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August 21, 2023
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