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Fuel and chemistry effects in high Karlovitz premixed turbulent flames

Lapointe, Simon and Blanquart, Guillaume (2016) Fuel and chemistry effects in high Karlovitz premixed turbulent flames. Combustion and Flame, 167 . pp. 294-307. ISSN 0010-2180. http://resolver.caltech.edu/CaltechAUTHORS:20160301-083406326

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Abstract

Direct numerical simulations of turbulent premixed flames at high Karlovitz numbers are performed using detailed chemistry. Different fuels, chemical mechanisms, and equivalence ratios are considered and their effects on turbulent flame speed, geometry of the reaction zone, and fuel burning rate are analyzed. Differential diffusion effects are systematically isolated by performing simulations with both non-unity and unity Lewis numbers. Heavy fuels with above unity Lewis numbers are considered. In the unity Lewis number limit, the n-heptane, iso-octane, toluene, and methane flames at a given reaction zone Karlovitz number present similar normalized turbulent flame speeds and fuel burning rates close to their respective laminar values. When differential diffusion effects are included, the turbulent flame speeds are lower than their unity Lewis number counterparts due to a reduction in the fuel burning rate. The turbulent reaction zone surface areas increase with the turbulence intensity but are not strongly affected by fuel, equivalence ratio, chemical mechanism, or differential diffusion. The geometry of the reaction zone is studied through the probability density functions of strain rate and curvature which are very similar when normalized by Kolmogorov scales at the reaction zone. The dependence of the chemical source terms on the scalar dissipation rate in the unity Lewis number case is shown and the distributions of scalar dissipation rate on the reaction surface are similar to those of passive scalars in homogeneous isotropic turbulence. The reduced burning rates in the presence of differential diffusion are discussed. The present results indicate that mean turbulent flame properties such as burning velocity and fuel consumption can be predicted with the knowledge of only a few global laminar flame properties. Once normalized by the corresponding laminar flame quantities, fuel and chemistry effects in high Karlovitz number premixed turbulent flames are mostly limited to differential diffusion.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.combustflame.2016.01.035DOIArticle
http://www.sciencedirect.com/science/article/pii/S001021801600050XPublisherArticle
ORCID:
AuthorORCID
Blanquart, Guillaume0000-0002-5074-9728
Additional Information:© 2016 The Combustion Institute. Published by Elsevier Inc. Received 26 October 2015; Revised 29 January 2016; Accepted 30 January 2016; Available online 25 February 2016. The authors gratefully acknowledge funding from Air Force Office of Scientific Research (FA9550-12-1-0472 and FA9550-12-1-0144) under supervision of Dr. Chiping Li and Fonds de Recherche du Québec–Nature et Techonologies for financial support. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575.
Funders:
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)FA9550-12-1-0472
Air Force Office of Scientific Research (AFOSR)FA9550-12-1-0144
Fonds de recherche du Québe-Nature et technologies (FRQ-NT)UNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
NSFACI-1053575
Subject Keywords:Turbulent premixed flames; High Karlovitz; Differential diffusion effects; Flame speed
Record Number:CaltechAUTHORS:20160301-083406326
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160301-083406326
Official Citation:Simon Lapointe, Guillaume Blanquart, Fuel and chemistry effects in high Karlovitz premixed turbulent flames, Combustion and Flame, Volume 167, May 2016, Pages 294-307, ISSN 0010-2180, http://dx.doi.org/10.1016/j.combustflame.2016.01.035. (http://www.sciencedirect.com/science/article/pii/S001021801600050X)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64893
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:01 Mar 2016 23:24
Last Modified:27 May 2016 20:20

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