In bluff body-stabilized flames, a variety of physical phenomena contribute to the flame destabilization as lean blowoff is approached. These effects include increased strain on the flame shear layers, decreased attenuation of Bénard-von Kármán vortex shedding, and the presence of thermoacoustic instabilities. Lean, bluff body-stabilized flames were studied in an enclosed rectangular-duct, turbulent combustion rig with a triangular flame holder under vitiated conditions with both symmetric and asymmetric fuel distributions. Air and fuel flows within the rig were characterized using a PIV system and a continuous emissions gas analyzer, respectively.
High-speed videos of these flames undergoing blowoff were taken to serve as the primary data source for analysis. To examine the effects of Bénard-von Kármán vortex instabilities and local strain-induced extinctions on the lean blowoff process, proper orthogonal decomposition (POD) algorithms were applied to the frames of the high-speed videos. POD mode shapes representing each of these phenomena were extracted and the relative contributions of these mode shapes were plotted over time as the flame approaches blowoff. Time-series analysis was also performed on a trace of the pressure oscillations and POD mode coefficients for a preliminary examination of the relevant acoustic influence on the blowoff event.
For future application to the turbulent combustion rig, a tunable diode laser absorption spectroscopy (TDLAS) system was developed. A TDL with a center wavelength in the near infrared region was simultaneously scanned across absorption lines of H2O and CO2 to obtain temperature and species concentration data. A McKenna Flat Flame burner was used to create a calibration environment for these measurements. Both direct and wavelength-modulated spectroscopy methods are examined, and their respective viability for use in the combustion rig is discussed.
","abstract_html":"<p>In bluff body-stabilized flames, a variety of physical phenomena contribute to the flame destabilization as lean blowoff is approached. These effects include increased strain on the flame shear layers, decreased attenuation of Bénard-von Kármán vortex shedding, and the presence of thermoacoustic instabilities. Lean, bluff body-stabilized flames were studied in an enclosed rectangular-duct, turbulent combustion rig with a triangular flame holder under vitiated conditions with both symmetric and asymmetric fuel distributions. Air and fuel flows within the rig were characterized using a PIV system and a continuous emissions gas analyzer, respectively. </p> <p>High-speed videos of these flames undergoing blowoff were taken to serve as the primary data source for analysis. To examine the effects of Bénard-von Kármán vortex instabilities and local strain-induced extinctions on the lean blowoff process, proper orthogonal decomposition (POD) algorithms were applied to the frames of the high-speed videos. POD mode shapes representing each of these phenomena were extracted and the relative contributions of these mode shapes were plotted over time as the flame approaches blowoff. Time-series analysis was also performed on a trace of the pressure oscillations and POD mode coefficients for a preliminary examination of the relevant acoustic influence on the blowoff event. </p> <p>For future application to the turbulent combustion rig, a tunable diode laser absorption spectroscopy (TDLAS) system was developed. A TDL with a center wavelength in the near infrared region was simultaneously scanned across absorption lines of H<sub>2</sub>O and CO<sub>2</sub> to obtain temperature and species concentration data. A McKenna Flat Flame burner was used to create a calibration environment for these measurements. Both direct and wavelength-modulated spectroscopy methods are examined, and their respective viability for use in the combustion rig is discussed.</p>","abstract_has_math":false,"creators":["Jensen, Trevor"],"institution":null,"degree_name":"Master of Science","degree_level":null,"degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Baki Cetegen, Thomas Barber","Michael Renfro"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-08-22T07:00:00Z","date_published":"2011-08-22T07:00:00Z","updated_at":"2026-07-24T06:31:45Z","subjects":["Bluff body","Combustion","POD","TDLAS","turbulent flame"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.lib.uconn.edu/gs_theses/141","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Baki Cetegen, Thomas Barber","Michael Renfro"]},{"key":"dc:creator","label":"Author","values":["Jensen, Trevor"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2011-08-22T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Bluff body","Combustion","POD","TDLAS","turbulent flame"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.lib.uconn.edu/gs_theses/141"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In bluff body-stabilized flames, a variety of physical phenomena contribute to the flame destabilization as lean blowoff is approached. These effects include increased strain on the flame shear layers, decreased attenuation of Bénard-von Kármán vortex shedding, and the presence of thermoacoustic instabilities. Lean, bluff body-stabilized flames were studied in an enclosed rectangular-duct, turbulent combustion rig with a triangular flame holder under vitiated conditions with both symmetric and asymmetric fuel distributions. Air and fuel flows within the rig were characterized using a PIV system and a continuous emissions gas analyzer, respectively.
High-speed videos of these flames undergoing blowoff were taken to serve as the primary data source for analysis. To examine the effects of Bénard-von Kármán vortex instabilities and local strain-induced extinctions on the lean blowoff process, proper orthogonal decomposition (POD) algorithms were applied to the frames of the high-speed videos. POD mode shapes representing each of these phenomena were extracted and the relative contributions of these mode shapes were plotted over time as the flame approaches blowoff. Time-series analysis was also performed on a trace of the pressure oscillations and POD mode coefficients for a preliminary examination of the relevant acoustic influence on the blowoff event.
For future application to the turbulent combustion rig, a tunable diode laser absorption spectroscopy (TDLAS) system was developed. A TDL with a center wavelength in the near infrared region was simultaneously scanned across absorption lines of H2O and CO2 to obtain temperature and species concentration data. A McKenna Flat Flame burner was used to create a calibration environment for these measurements. Both direct and wavelength-modulated spectroscopy methods are examined, and their respective viability for use in the combustion rig is discussed.
"]},{"key":"dc:title","label":"Title","values":["An Optical Analysis of the Blowoff Behavior for Bluff Body-Stabilized Flames in Vitiated Flow"]}]}],"canonical_facts":{"dc:contributor":["Baki Cetegen, Thomas Barber","Michael Renfro"],"dc:creator":["Jensen, Trevor"],"dc:date.available":["2011-08-22T07:00:00Z"],"dc:description.abstract":["In bluff body-stabilized flames, a variety of physical phenomena contribute to the flame destabilization as lean blowoff is approached. These effects include increased strain on the flame shear layers, decreased attenuation of Bénard-von Kármán vortex shedding, and the presence of thermoacoustic instabilities. Lean, bluff body-stabilized flames were studied in an enclosed rectangular-duct, turbulent combustion rig with a triangular flame holder under vitiated conditions with both symmetric and asymmetric fuel distributions. Air and fuel flows within the rig were characterized using a PIV system and a continuous emissions gas analyzer, respectively.
High-speed videos of these flames undergoing blowoff were taken to serve as the primary data source for analysis. To examine the effects of Bénard-von Kármán vortex instabilities and local strain-induced extinctions on the lean blowoff process, proper orthogonal decomposition (POD) algorithms were applied to the frames of the high-speed videos. POD mode shapes representing each of these phenomena were extracted and the relative contributions of these mode shapes were plotted over time as the flame approaches blowoff. Time-series analysis was also performed on a trace of the pressure oscillations and POD mode coefficients for a preliminary examination of the relevant acoustic influence on the blowoff event.
For future application to the turbulent combustion rig, a tunable diode laser absorption spectroscopy (TDLAS) system was developed. A TDL with a center wavelength in the near infrared region was simultaneously scanned across absorption lines of H2O and CO2 to obtain temperature and species concentration data. A McKenna Flat Flame burner was used to create a calibration environment for these measurements. Both direct and wavelength-modulated spectroscopy methods are examined, and their respective viability for use in the combustion rig is discussed.
"],"dc:identifier":["https://digitalcommons.lib.uconn.edu/gs_theses/141"],"dc:subject":["Bluff body","Combustion","POD","TDLAS","turbulent flame"],"dc:title":["An Optical Analysis of the Blowoff Behavior for Bluff Body-Stabilized Flames in Vitiated Flow"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_name":["Master of Science"]},"updated_at":"2026-07-24T06:31:45Z"}