Propagating edge-flame response to multiple stoichiometry gradients

Stanislav Kostka, William F. Carnell, Michael W. Renfro

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

A five-slot contoured nozzle burner was used to create multiple lifted partially premixed flames in close proximity. The burner permits the stoichiometry gradient below each edge flame and the separation distance between stabilization points of the flames to be separately controlled. In previous work, we showed that edge-flame interactions lead to a bifurcation in the flame stabilization, where the liftoff height of neighboring edge flames differs even in symmetric flow fields. As the composition gradient below each flame is decreased, the edge flames broaden. Flow around the edge flames leads to an aerodynamic interaction, where upstream conditions below one flame are modified by the neighboring flame. These interactions cause a liftoff height difference between the two flames. Further reduction of stoichiometry gradient causes the neighboring flames to merge and approach the structure of a single premixed flame. In this work, the equivalence ratio gradient and separation distance between stoichiometric points were varied by controlling the burner slot equivalence ratios, so that these interactions could be studied in greater detail. Rayleigh scattering was used to measure flame curvature and calculate local stoichiometry gradients below each flame stabilization point. Planar laser-induced fluorescence signals of hydroxyl and formaldehyde were measured to provide qualitative comparisons of relative reaction rates between flames. Neighboring edge flames were found to behave based solely on local conditions below each flame. Only aerodynamic interactions were observed and no chemical or thermal interactions, caused by heat or radical transport between flames, were observed. The bifurcated flame response can be described simply from the effects that flow around the flame structure has on local velocities and scalar dissipation rates.

Original languageEnglish
Pages (from-to)82-95
Number of pages14
JournalCombustion and Flame
Volume154
Issue number1-2
DOIs
StatePublished - Jul 2008

Bibliographical note

Funding Information:
The authors thank Nathan Hemming and Thomas J. Mealy, of the University of Connecticut, for fabrication of the burner used for experimentation. This work was funded by the National Science Foundation (CTS#0235114).

Keywords

  • Formaldehyde PLIF
  • Hydroxyl PLIF
  • Lifted edge flames
  • Rayleigh scattering
  • Stoichiometry gradient

ASJC Scopus subject areas

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

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