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Brown, Corey D.; Watson, K.A.; Lyons, Kent

doi:10.1023/a:1009925500084

Cited by 50 publications

(16 citation statements)

References 16 publications

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“…Inversion of the slopes of lift-off curves with increased co-flow velocity was observed earlier in [ 10] for ethylene. Data was not plotted with h vs Uj axes but instead with axes showing Uc vs Uj and where each curve corresponds to a given h. It is interesting to verify if data presented in Fig.…”

Section: Discussionsupporting

confidence: 62%

“…Data was not plotted with h vs Uj axes but instead with axes showing Uc vs Uj and where each curve corresponds to a given h. It is interesting to verify if data presented in Fig. 3 show a similar slope inversion if it is plotted with the alternative axes used in [ 10], Uc vs Uj. This is done in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In a parametric study of the effects of the co-flow velocity on lifted flames, Brown et al [ 10], have reported a transition in the stabilization mechanism of ethylene with increasing co-flow velocity Uc.…”

Section: Introductionmentioning

confidence: 99%

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Pressure effects and transition in the stabilization mechanism of turbulent lifted flames

Guiberti

Boyette

Roberts

et al. 2019

Proceedings of the Combustion Institute

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This study reports novel measurements on the effects of pressure on the lift-off behavior and the stabilization mechanism of turbulent non-premixed methane jet flames. A high-pressure combustion duct (HPCD) was operated within the range of pressure P = to 7 bar using jet velocities of 4 m.s-1  Uj  30 m.s-1 and co-flow velocities of 0.23 m.s-1  Uc  0.60 m.s-1. Lift-off heights were measured from chemiluminescence pictures while joint images of hydroxyl and velocity, performed using joint PLIF-OH/PIV, were used to extract information about the stabilization mechanism. It is shown that while the lift-off height generally increases with pressure, the impact of pressure depends on the magnitude of the co-flow velocity. For Uc = 0.30 m.s-1 , the flame's base remains near the nozzle over the entire pressure range and the measured flame speeds indicate that edge-flame stabilization is dominant. The slope of the lift-off height vs jet velocity curves is positive. For Uc = 0.60 m.s-1 and P > 2 bar, the flame stabilizes further downstream and a transition to turbulent premixed flame propagation appears to have occurred. At these conditions, the slope of the lift-off height vs jet velocity curves becomes negative. This reversal at high pressure is a new result for methane. More importantly, the transition in the stabilization mechanism with increasing Uc is consistent with results reported earlier for ethylene and appears to be independent of the fuel.

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Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

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Pressure effects and transition in the stabilization mechanism of turbulent lifted flames

Guiberti

Boyette

Roberts

et al. 2019

Proceedings of the Combustion Institute

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“…These leading edge flames are often present at the stabilization point of lifted spray investigated by a twodimensional laser-sheet imaging technique, as has been described earlier. The nature of the flamefront in the stabilization region of the spray-jet flame is vibrant topic of research [34][35][36], along with the corresponding work in gaseous flames [39][40][41][42][43][44][45][46][47]. Whether all spray flames exhibit "leading edge' flame structures as shown by our group for the gaseous and for some spray cases case is a major question to be addressed by our group in future work.…”

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 84%

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

Lyons¹

2004

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Public Reporting burden for this collection of information is estimated to average I hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send conmient regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188,) Washington, DC 20503.

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“…Brown et al have studied the effect of jet exit velocity and coflow velocity on liftoff height [5]. They discovered that the former has a minimal effect on lifted flames that are significantly downstream from the burner exit (i.e., in the far field).…”

Section: Introductionmentioning

confidence: 99%

Flame Propagation and Blowout in Hydrocarbon Jets: Experiments to Understand the Stability and Structure

Lyons¹

2012

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. This research supported by the U.S. Army Research Office examines a myriad of facets of lifted hydrocarbon jet flames in the presence of air co-flow. At a certain jet exit velocity, a flame will lift from the fuel nozzle and stabilize at some downstream position. The partially-premixed flame front of the lifted flame oscillates, with the oscillations becoming greater in flames stabilized further downstream. These Inventions (DD882) Scientific ProgressThe main advances in jet flame flow interaction in oblique jet/air flows, as well as flame blowout, are detailed in the attachment. blowout were compared against two parameters: nozzle angle and coflow velocity. The resulting correlations indicated that flames at more oblique angles have a greater upper stability limit and were more resistant to changes in coflow velocity. This behavior occurs due to a lower effective coflow velocity at angles more oblique to the coflow direction.Additionally, stability limits were determined for flames in crossflow and mild counterflow configurations, and a relationship between the liftoff and blowout velocities was observed.For flames in crossflow and counterflow, the stability limits are higher. Further studies may include more angle and coflow combinations, as well as the effect of diluents or different fuel types. IntroductionA multitude of studies have been performed on lifted jet flames and their behavior in various air flow configurations. In such partially-premixed flames, the characteristics of the surrounding air flow (velocity, temperature) can strongly impact the overall combustion process and the stability parameters. As fuel flows from a nozzle and mixes with the air, the fuel and oxidizer concentrations vary throughout space and time. The extent of mixing due to turbulence also changes depending on the surrounding flow. The perpetually varying concentrations help to determine the overall behavior of a flame: its shape, velocity, size, color, temperature, and composition. In parallel, the heat release serves to laminarize regions, and serves to limit reducing mixing.In particular, two important behavioral parameters are liftoff and blowout velocity.Initially, a jet flame will remain attached to the nozzle at low fuel velocities. However, at a critical jet velocity, the flame will lift off from the nozzle and stabilize at a position While jet behavior in coflow has been extensively studied, less attention has been devoted to jets in crossflow. In a review, Bandaru and Turns included a comprehensive list of all major crossflow research to date [9]. Many of the works relevant to this study were observation-based experiments performed by Kalghatgi, whosecrossflow flame experiments were conducted in a wind tunnel and involved propane, ...

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Cited by 50 publications

References 16 publications

Pressure effects and transition in the stabilization mechanism of turbulent lifted flames

Pressure effects and transition in the stabilization mechanism of turbulent lifted flames

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

Flame Propagation and Blowout in Hydrocarbon Jets: Experiments to Understand the Stability and Structure

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