Influence of advective heat flux on extinction scalar dissipation rate and velocity in negative edge flames

W. F. Carnell, M. W. Renfro

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

A counterflow flame geometry, which has previously been experimentally shown to produce stable negative edge flames, was studied using numerical simulations. In this geometry, the flame edge is formed off the counterflow centreline owing to a local increase in scalar dissipation rate. Hot products from the stable nonpremixed flame on the centreline flow through the edge at velocities of ∼1-5 m/s. The size of the counterflow burner and the gas flowrates are varied in the simulations to alter the flame strength and velocity at the flame edge. The advection of products through the edge is shown to extend the flame extinction to higher scalar dissipation rates than required for centreline extinction. For high velocities, the scalar dissipation rate required for flame extinction can be related to the centreline extinction value by considering only the effect of energy addition to the flame edge via advection. However, for lower edge flame velocities, the effects of increased thermal and species diffusion through the edge must also be included. Since the advection at the edge is a product of both the local velocity and temperature gradient, a single correlation between the scalar dissipation rate and the negative edge flame velocity does not exist.

Original languageEnglish
Pages (from-to)815-830
Number of pages16
JournalCombustion Theory and Modelling
Volume10
Issue number5
DOIs
StatePublished - Oct 2006

Bibliographical note

Funding Information:
This work was funded by the National Science Foundation (CTS-0235114), with Dr Linda Blevins serving as grant manager. We appreciate the assistance of Graham Goldin (FLUENT Inc.) with aspects of the numerical simulations.

Keywords

  • Edge flame velocity
  • Flame extinction
  • Flame holes
  • Negative edge flames
  • Scalar dissipation rate

ASJC Scopus subject areas

  • Chemistry (all)
  • Chemical Engineering (all)
  • Modeling and Simulation
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy (all)

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