Toward an understanding of the stabilization mechanisms of lifted turbulent jet flames: Experiments

Lyons, Kent

doi:10.1016/j.pecs.2006.11.001

Cited by 259 publications

(105 citation statements)

References 114 publications

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“…The computations in [8] show that a smaller pipe diameter gives better penetration of the air and greater leaning-off of the mixture, leading to earlier localised flame extinctions and blow-off. 6 Details of how a blow-off develops were studied experimentally by AP at the State Key Laboratory in Fire Science, Hefei. Subsonic jet flames of methane and propane were employed, with pipe diameters ranging between 3 and 8 mm, as described in [4].…”

Section: Lift-off Distance Subsonic and Choked Blow-offmentioning

confidence: 99%

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Generalised correlations of blow-off and flame quenching for sub-sonic and choked jet flames

Palacios

Bradley

2017

Combustion and Flame

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Dimensionless groups suggested by the mathematical modelling of subsonic fuel jet flames, and extensive experimental data, have been reasonably successsful in correlating dimensionles flame heights and flame lift-off distances in terms of a dimensionless flow number. This approach is extended to the more exacting correlations that define regimes of flame quenching, blow-off, and lifted flames.Experimental data from these diverse sources are analysed, and the bounds of these regimes are expressed in terms of the critical minimum jet pipe diameter to avoid blow-off, normalised by the laminar flame thickness for the maximum burning velocity mixture, and the flow number. The regimes extend from low Reynolds number laminar flows in hypodermic tubes to high Reynolds number choked flows, with supersonic shocks.Data are well corrrelated in the subsonic regime for a range of hydrocarbon gases, in which critical pipe diameters for the avoidance of blow-off increase with flow number. Matters are more complex in the extended choked flow regime, in which there are less data. This regime of supersonic flow and shock waves is one of improved fuel/air mixing and enhanced reactivity, to such an extent that the critical pipe diameter, after reaching a maximum, decreases. Data are presented in this regime, and indeed over the full range of conditions, for methane, propane and hydrogen jet flames. Hydrogen exhibits more reactive characteristics than the hydrocarbons. In terms of the correlating parameters, whereas laminar flame thickness is related to that of the non-reacting preheat zone, such a zone is difficult 2 to define with hydrogen, as a consequence of the upstream diffusion of H atoms, and this aspect is discusssed.

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Section: Lift-off Distance Subsonic and Choked Blow-offmentioning

confidence: 99%

“…A review of the extensive experimental data on jet flame heights and lift-off distances is presented in [5]. The associated detailed flame structure of lifted hydrocarbon turbulent jet flames and their stability has been discussed by Lyons [6], along with a review of turbulent lifted flame theories.…”

Section: Introductionmentioning

confidence: 99%

Generalised correlations of blow-off and flame quenching for sub-sonic and choked jet flames

Palacios

Bradley

2017

Combustion and Flame

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“…In combustion systems where the fuel is injected as a fuel-rich mixture, the flame propagates by partially premixed and turbulent triple flame processes [1]. Various studies of triple flames are reviewed by Lyons [26]. Triple flame stabilization is still not well understood but numerical and experimental studies suggest that a triple flame is less sensitive to strain than a pure diffusion flame and that triple flame displacement speeds can be several times greater than the laminar flame speed at stoichiometry [26].…”

Section: Introductionmentioning

confidence: 99%

“…To extend the model to partially premixed and non-premixed combustion, a sensor S (constructed as a reaction rate) is used to trigger the TFLES model only in reactive areas without affecting inert mixing away from the flame front [40,57,58]. Finally, in non-reactive regions (S = 0, F = 1, E = 1), standard LES equations (without chemical source terms) apply and in the flame front (S = 1), thickened equations apply, with:ω Although this approach is still being developed and requires further validations, its simplicity and its success in prior applications [40,58,59] suggest its suitability for the problem addressed in this work where the propagation and stabilization processes of the turbulent lifted flame involve premixed and diffusion combustion regimes [26].…”

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confidence: 99%

Large eddy simulation of spark ignition in a turbulent methane jet

Lacaze

Richardson

Poinsot

2009

Combustion and Flame

135

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Large Eddy Simulation (LES) is used to compute the spark ignition in a turbulent methane jet flowing into air. Full ignition sequences are calculated for a series of ignition locations using a one-step chemical scheme for methane combustion coupled with the thickened flame model. The spark ignition is modeled in the LES as an energy deposition term added to the energy equation. Flame kernel formation, the progress and topology of the flame propagating upstream, and stabilization as a tubular edge flame are analyzed in detail and compared to experimental data for a range of ignition parameters. In addition to ignition simulations, statistical analysis of non-reacting LES solutions are carried out to discuss the ignition probability map established experimentally.

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“…Many explanations of the flame stabilization mechanism of turbulent lifted jet flames are available [1,2,3] which are utilized in this research in understanding lifted H 2 jet flame stability. Peters [4] explains that quenching near the nozzle due to excessive local strain rates precedes liftoff.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pressure, Environment Temperature, Jet Velocity and Nitrogen Dilution on the Liftoff Characteristics of a N2-in-H2 Jet Flame in a Vitiated Co-flow

et al. 2014

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The CO 2 emission prevention advantage of generating power with high hydrogen content fuels using gas turbines motivates an improved understanding of the ignition behavior of hydrogen in premixed and partially premixed environments. Hydrogen rich fueled flame stability is sensitive to operating conditions, including environment pressure, temperature, and jet velocity. Furthermore, when premixed or partially premixed operation is needed for nitric oxide emissions reduction, a diluent, such as nitrogen, is often added in allowing fuel/air mixing prior to combustion. Thus, the concentration of the diluent added is an additional independent variable on which flame stability dependence is needed. The focus of this research is on characterizing the dependence of hydrogen jet flame stability on environment temperature, pressure, jet velocity and diluent concentration by determining the dependence of the liftoff height of lifted flames on these 4 independent parameters. Nitrogen is used as the diluent due to its availability and effectiveness in promoting liftoff. A correlation modeling the liftoff height dependence on operating conditions is developed which emphasizes the factors that bear the greatest impact on ignition behavior.

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Toward an understanding of the stabilization mechanisms of lifted turbulent jet flames: Experiments

Cited by 259 publications

References 114 publications

Generalised correlations of blow-off and flame quenching for sub-sonic and choked jet flames

Generalised correlations of blow-off and flame quenching for sub-sonic and choked jet flames

Large eddy simulation of spark ignition in a turbulent methane jet

Effect of Pressure, Environment Temperature, Jet Velocity and Nitrogen Dilution on the Liftoff Characteristics of a N2-in-H2 Jet Flame in a Vitiated Co-flow

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