• Journal of Hydrogen and New Energy
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• v.30 no.1
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• pp.67-75
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• 2019

An experimental study was conducted to measure laminar burning velocity and Markstein length of SNG fuel with 3% of hydrogen contents from spherical propagating flames at normal and elevated initial pressure. These results were compared with numerical calculations by Premix code with GRI-mech 3.0, USC II and UC San Diego to provide suitable mechanism for SNG fuel. As a result of this work, it was found that the burning velocities and Markstein lengths of SNG fuel decrease with increase of initial pressure regardless of equivalence ratio. In addition, numerical calculations with GRI-mech 3.0 were coincided with experimental results.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.207-209
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• 2012

The present experiment was conducted to measure the unstretched laminar burning velocity and cellular instability of DME-air and syngas (in steps of 25 %) added DME-air premixed flames using propagating spherical flame. The experimental results were discussed in two focuses which are effects of syngas fraction and initial pressure on Markstein length, unstretched laminar burning velocities, and cellular instability. The flame instability was evaluated by the Markstein length and cellularity which is caused by diffusional-thermal instability and hydrodynamic instability.

• Journal of the Korean Society of Combustion
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• v.17 no.4
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• pp.44-50
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• 2012

The present study was conducted to investigate the flame instability(evaluated by Markstein length and cellular instability) and laminar burning velocity in a constant volume combustion chamber at room temperature and elevated pressure up to 0.3 MPa to suggest the possibility of utilizing mixtures of syngas added DME-air premixed flames in internal combustion engines. The experimentally measured laminar burning velocities were compared to predictions calculated the PREMIX code with Zhao reaction mechanism. Discussions were made on effects of syngas addition into DME-Air premixed flames through evaluating laminar burning velocity, Markstein length, and cellular instability. Particular concerns are focused on cellular instability caused by hydrodynamic instability and diffusive-thermal instability.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.72-83
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• 2010

Experiments were conducted to investigate the effects of added diluents (carbon dioxide, nitrogen, and helium) on cellular instabilities in outwardly propagating spherical syngas-air premixed flames. Laminar burning velocities and Markstein lengths were measured by analyzing high-speed schlieren images at various diluent concentrations and equivalence ratios. Experimental results showed substantial reduction of the laminar burning velocities and of the Markstein lengths with the diluent additions in the fuel blends. Effective Lewis numbers of helium-diluted syngas-air flames increased but those of carbon dioxide- and nitrogen-diluted syngas-air flames decreased in increase of diluents in the reactant mixtures. With helium diluent, the propensity for cells formation was significantly diminished, whereas the cellular instabilities for carbon dioxide- and nitrogen-diluted syngas-air flames were not suppressed.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.287-289
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• 2015

Meso-scale combustion is defined as combustion phenomena within limited characteristic length scales that are comparable with the laminar flame length scales. In the laminar flame theory, four representative length scales have been involved; i.e., a reaction layer thickness, a thermal layer thickness, a quenching distance, and a Markstein length. When the effects of these length scales on the flame characteristics are understood, the laminar flame theories can be clarified. Therefore, a study on the meso-scale combustion phenomena should not be thought as just a specific phenomena occurring in an exceptional combustion condition. Instead, all combustion phenomena within meso-scale spaces need to be explained by our knowledge. During this challenge, our understanding on laminar flame structures can be extended. Considering that most turbulent combustion phenomena in engineering application are still have local laminar flame structures, studies on laminar flame structures need to be re-visited especially in academic aspects.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.23-32
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• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.109-112
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• 2015

This article describes a cellular instability and laminar burning velocity of simulated synthetic natural gas(SNG) including 3% hydrogen. In this study, experimental apparatus is employed using cylindrical bomb combustor, and investigation is carried out with high speed camera and Schlieren system. The cellular instability is caused by the buoyancy, hydrodynamic instability. Unstretched burning velocity can be determined by extrapolated stretch rate of zero point from measured results. These results were also compared with numerical calculation by Chemkin package with GRI 3.0, USC-II, WANG, C3 Fuel mechanism. As an experimental conditions, equivalence ratios was adjusted from 0.8 to 1.3. From results of this work, the one was found that the cellular instability has occurred by effect of thermal expansion rate and flame thickness. As the other results, unstretched laminar burning velocity was best coincided with GRI 3.0 mechanism.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.165-168
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• 2015

To measure laminar burning velocity in methane/air/ethylene mixture flame, propagating centrally ignited spherical premixed flame to radial direction was measured by high-speed schlieren images with elevated pressure. In this study, The experimentally measured unstretched laminar burning velocities of methane was compared with GRI mech 3.0 to validate experimental data and choose the radius range, respectively. numerical prediction using the PREMIX code with GRI mech 3.0, USC mech II,, and Wang mech were evaluated through comparison with experimental burning velocity with consideration of extrapolation on linear/nonlinear model.