Presentation Title

Thermo-acoustic Instabilities Present in the Combustion of Laminar Diffusion Methane Flames

Faculty Mentor

Ann R. Karagozian

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

152

Session

poster 4

Type of Presentation

Poster

Subject Area

engineering_computer_science

Abstract

The interactions between acoustic waves and a combustion process can lead to combustion instabilities that are detrimental to combustor life and performance. Thermo-acoustic instabilities arise from these interactions in the form of self-exciting large amplitude pressure oscillations coupled with the natural acoustic modes of the combustion chamber. In this study acoustically coupled combustion instabilities associated with methane diffusion flames were investigated using a cylindrical waveguide equipped with a moveable speaker assembly. The speakers were actuated to generate a standing wave with an acoustic frequency of 332Hz and various prescribed oscillatory pressure amplitudes. Single and triple reactive methane microjet configurations were used. High speed visible and phase-locked OH* chemiluminescence images were obtained to quantify flame dynamics via proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). Lifting of the flames for the triple burner was observed and the two outer flames tilted inwards forming wing like geometries. Forcing conditions that lead to high instability with large flapping-like dynamics and eventually extinction were identified.

Keyword: Combustion, Propulsion, Instabilities, Thermo, Acoustics, Heat

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Thermo-acoustic Instabilities Present in the Combustion of Laminar Diffusion Methane Flames

152

The interactions between acoustic waves and a combustion process can lead to combustion instabilities that are detrimental to combustor life and performance. Thermo-acoustic instabilities arise from these interactions in the form of self-exciting large amplitude pressure oscillations coupled with the natural acoustic modes of the combustion chamber. In this study acoustically coupled combustion instabilities associated with methane diffusion flames were investigated using a cylindrical waveguide equipped with a moveable speaker assembly. The speakers were actuated to generate a standing wave with an acoustic frequency of 332Hz and various prescribed oscillatory pressure amplitudes. Single and triple reactive methane microjet configurations were used. High speed visible and phase-locked OH* chemiluminescence images were obtained to quantify flame dynamics via proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). Lifting of the flames for the triple burner was observed and the two outer flames tilted inwards forming wing like geometries. Forcing conditions that lead to high instability with large flapping-like dynamics and eventually extinction were identified.

Keyword: Combustion, Propulsion, Instabilities, Thermo, Acoustics, Heat