Direct Numerical Simulation of turbulent nonpremixed "cool" flames: Applicability of flamelet models

Alex G. Novoselov, Chung K. Law, Michael E. Mueller

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

"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.

Original languageEnglish (US)
Pages (from-to)2143-2150
Number of pages8
JournalProceedings of the Combustion Institute
Volume37
Issue number2
DOIs
StatePublished - Jan 1 2019

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • "Cool" flames
  • Direct numerical simulation (DNS)
  • Turbulent nonpremixed combustion

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