TY - JOUR
T1 - Direct Numerical Simulation of turbulent nonpremixed "cool" flames
T2 - Applicability of flamelet models
AU - Novoselov, Alex G.
AU - Law, Chung K.
AU - Mueller, Michael E.
N1 - Funding Information:
A.G.N. and C.K.L. gratefully acknowledge funding from the Microgravity Combustion program at NASA Grant no. NNX15AC79A. The authors gratefully acknowledge valuable support in the form of computational time on the TIGRESS high performance computer center at Princeton University, which is jointly supported by the Princeton Institute for Computational Science and Engineering (PICSciE) and the Princeton University Office of Information Technology’s Research Computing Department.
Publisher Copyright:
© 2018 The Combustion Institute.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019
Y1 - 2019
N2 - "Cool" flames result from the coupling of low-temperature chemistry with molecular transport. These flames have been experimentally and computationally observed under laminar flow conditions but have not been isolated under turbulent flow conditions. In this work, a skeletal n-heptane chemical mechanism including low-temperature chemistry is used to conduct two-dimensional Direct Numerical Simulations (DNS) of nonpremixed "cool" flames subjected to unsteady, two-dimensional flow initialized from a plane of isotropic turbulence. Like conventional "hot" flames, at high Damköhler numbers, these "cool" flames are found to be adequately described by a steady flamelet model. However, at low Damköhler numbers, both nonpremixed and premixed behavior is observed locally. When the combustion is locally nonpremixed, these "cool" flames can be described by the unsteady flamelet model only if the correct scalar dissipation rate profile and associated boundary conditions are considered.
AB - "Cool" flames result from the coupling of low-temperature chemistry with molecular transport. These flames have been experimentally and computationally observed under laminar flow conditions but have not been isolated under turbulent flow conditions. In this work, a skeletal n-heptane chemical mechanism including low-temperature chemistry is used to conduct two-dimensional Direct Numerical Simulations (DNS) of nonpremixed "cool" flames subjected to unsteady, two-dimensional flow initialized from a plane of isotropic turbulence. Like conventional "hot" flames, at high Damköhler numbers, these "cool" flames are found to be adequately described by a steady flamelet model. However, at low Damköhler numbers, both nonpremixed and premixed behavior is observed locally. When the combustion is locally nonpremixed, these "cool" flames can be described by the unsteady flamelet model only if the correct scalar dissipation rate profile and associated boundary conditions are considered.
KW - "Cool" flames
KW - Direct numerical simulation (DNS)
KW - Turbulent nonpremixed combustion
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U2 - 10.1016/j.proci.2018.06.191
DO - 10.1016/j.proci.2018.06.191
M3 - Article
AN - SCOPUS:85049661748
SN - 1540-7489
VL - 37
SP - 2143
EP - 2150
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 2
ER -