Time-resolved blowoff transition measurements for two-dimensional bluff body-stabilized flames in vitiated flow

Steven G. Tuttle, Swetaprovo Chaudhuri, Stanislav Kostka, Kristin M. Kopp-Vaughan, Trevor R. Jensen, Baki M. Cetegen, Michael W. Renfro

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Flame holding and blowoff characteristics of bluff-body stabilized, turbulent flames were measured in an enclosed rectangular duct with a triangular flame holder in vitiated, premixed flows. Blowoff stability margins were characterized with chemiluminescence measurements performed by high-speed imaging to capture flame dynamics during the approach to flame blow off. As the equivalence ratio was decreased, local extinctions along the flames interacting with shear layers surrounding the bluff body recirculation zone occurred with greater frequency and proximity to the wake stagnation zone. Decreased equivalence ratio resulted in extinction events at the trailing edge of the stagnation zone, which allowed reactants to be convected into the recirculation zone and burned behind the bluff body. Increasing reactant dilution of the recirculation zone eventually resulted in flame lift-off or extinction of the flame in the neighboring shear layer. These near field shear layer flames convected to the wake stagnation zone, and were eventually quenched. Simultaneous particle imaging velocimetry (PIV) and OH planar laser-induced fluorescence (PLIF) measurements captured the flame edge location and aerodynamic behavior as blowoff was approached. Two-dimensional hydrodynamic stretch along the flame front and flow field vorticity maps were extracted from the combined PIV/OH PLIF data. The distribution of flame stretch shifted to greater values as the equivalence ratio decreased and is believed to be the cause of local flame extinction in the wake stagnation zone that starts the blowoff process.

Original languageEnglish
Pages (from-to)291-305
Number of pages15
JournalCombustion and Flame
Volume159
Issue number1
DOIs
StatePublished - 2012

Bibliographical note

Funding Information:
This work has been supported by the National Science Foundation under Grant CBET-0967474 and Pratt & Whitney Center of Excellence at UConn. We acknowledge Dr. Jeffrey Cohen’s assistance in arranging the borrowing of the Phantom camera from UTRC for this study. We would also like to thank Steven L. Tuttle, of Tuttle Tool & Manufacturing for his precision machining of the cooled and instrumented flame holder and undergraduate laboratory assistants, Mark Scarzella and Marat Kulakhmetov for their help in conducting the reported experiments.

Keywords

  • Bluff body flames
  • High-speed imaging
  • PIV
  • PLIF
  • Premixed
  • Turbulent
  • Vitiated flow

ASJC Scopus subject areas

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

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