Visualization of shear layer dynamics in a transversely forced flow and flame

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This study addresses the response of a swirling annular jet flow and flameto transverse acoustic excitation in order to better describe key velocity-coupled processes during transverse combustion instabilities in lean, premixed flames. In particular, visualization and velocimetry techniques provide information about the effectsofacoustic excitation on unsteady vortex developmentin the shear layers. Without acoustic forcing, the shear layers roll upinto small vortices, driven by the Kelvin-Helmholtz instability, that convect downstream and grow. In the presence of high-amplitude acoustic forcing, as would be present during a combustion instability, the acoustic oscillations drive shear layer vortices to undergo a strong rollup event. Smoke visualization provides visual evidence of the rollup, while particle image velocimetry measurements show the development and trajectory of this large structure. Finally, planar laser-induced fluorescence of OH shows how the large coherent structure causes flame wrinkling at the base of the flame. The vortex rollup, responding at the frequency of acoustic forcing, creates large-scale wrinkles on the flame and can be the main driver of flame response during combustion instability.

Original languageEnglish (US)
Pages (from-to)1127-1136
Number of pages10
JournalJournal of Propulsion and Power
Volume31
Issue number4
DOIs
StatePublished - Jan 1 2015

Fingerprint

shear layers
combustion stability
visualization
flames
acoustics
Visualization
Acoustics
vortex
vortices
Vortex flow
combustion
Velocity measurement
acoustic excitation
wrinkling
Kelvin-Helmholtz instability
swirling
jet flow
premixed flames
smoke
particle image velocimetry

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Fuel Technology
  • Mechanical Engineering
  • Space and Planetary Science

Cite this

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title = "Visualization of shear layer dynamics in a transversely forced flow and flame",
abstract = "This study addresses the response of a swirling annular jet flow and flameto transverse acoustic excitation in order to better describe key velocity-coupled processes during transverse combustion instabilities in lean, premixed flames. In particular, visualization and velocimetry techniques provide information about the effectsofacoustic excitation on unsteady vortex developmentin the shear layers. Without acoustic forcing, the shear layers roll upinto small vortices, driven by the Kelvin-Helmholtz instability, that convect downstream and grow. In the presence of high-amplitude acoustic forcing, as would be present during a combustion instability, the acoustic oscillations drive shear layer vortices to undergo a strong rollup event. Smoke visualization provides visual evidence of the rollup, while particle image velocimetry measurements show the development and trajectory of this large structure. Finally, planar laser-induced fluorescence of OH shows how the large coherent structure causes flame wrinkling at the base of the flame. The vortex rollup, responding at the frequency of acoustic forcing, creates large-scale wrinkles on the flame and can be the main driver of flame response during combustion instability.",
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Visualization of shear layer dynamics in a transversely forced flow and flame. / O'Connor, Jacqueline.

In: Journal of Propulsion and Power, Vol. 31, No. 4, 01.01.2015, p. 1127-1136.

Research output: Contribution to journalArticle

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