Study on flame structure and extinction mechanism of dimethyl ether spherical diffusion flames

Kang, Yinhu; Wang, Qiang; Zhang, Pengyuan; Liu, Congcong; Lu, Xiaofeng; Wang, Quanhai

doi:10.1016/j.energy.2019.116786

Cited by 8 publications

(6 citation statements)

References 39 publications

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“…At the ambient side, mass fractions of the ambient species (including He and O 2 for the NDFs, or DME and Ar for the IDFs) were constrained; while that of the other species were relaxed with zero gradient, as eq () shows. The applicability and accuracy of the present models in the simulations of spherical diffusion flame were extensively verified in the literature. − …”

Section: Details Of the Numerical Simulationmentioning

confidence: 59%

“…Meanwhile, the maximum number of grid points was controlled by the keyword "NTOT". Our previous studies 29,30 verified that GRAD = CURV = 0.1 and NTOT = 1000 can guarantee grid independency; hence, they were used for the present simulations.…”

Section: Mass Equationmentioning

confidence: 83%

“…To validate the accuracy and reliability of the computational code, a hot NDF (established at the oxygen mole fraction X O 2 = 50%) was assumed as a reference case. The predicted results of the temperature and species CO 2 and O 2 were compared with the experimental results from ref ( 30 ). As displayed in Figure 2 , it can be seen that the predicted temperatures of hot NDF were perfectly in agreement with the measured results, except for those in the high-temperature region ( T > 1300 K).…”

Section: Details Of the Numerical Simulationmentioning

confidence: 99%

“… Comparisons between the predicted and measured 30 temperature and species mole fractions at the oxidizer composition of 50% O 2 /50% He under hot NDF condition. …”

Section: Details Of the Numerical Simulationmentioning

confidence: 99%

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Comparative Study on the Dimethyl Ether Combustion Characteristics in Normal and Inverse Diffusion Spherical Flame Geometries

et al. 2020

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This paper makes a comparative study on the normal diffusion flame (NDF) and inverse diffusion flame (IDF) characteristics of dimethyl ether (DME) in microgravitational spherical diffusion flame geometry by simulations with detailed fuel chemistry and a transport model. It is found that there always existed two combustion modes (i.e., hot flame and cool flame) in either NDF or IDF condition. The combustion progress of hot flames was controlled by diffusive mixing, while that of cool flames was controlled by low-temperature competing kinetics. The cool-flame structure dynamics were far away from the chemical equilibrium. The low-temperature branching rate of DME was positively dependent on the oxygen level, while its termination rate was enhanced with the increasing temperature. Being rather distinct from the NDF counterpart, DME IDFs had the oxygen-enriched combustion feature in either hot- or cool-flame condition. Furthermore, DME hot-flame extinction was induced by thermal radiative loss, while the cool-flame extinction was induced especially by the decrease of the low-temperature branching rate. Compared with hot NDFs, it would be of less effectiveness to control the hot IDF combustion process by positive measures. However, combustion in the latter configuration was much more stable than the former. In either NDF or IDF geometry, the cool-flame chemistry could help to extend the fuel flammability range considerably, and the two-reaction-zone structure of cool flame was responsible for cool-flame stability. In addition, the IDFs had much better ignition performance than the NDF counterpart.

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Section: Details Of the Numerical Simulationmentioning

confidence: 59%

Section: Mass Equationmentioning

confidence: 83%

Section: Details Of the Numerical Simulationmentioning

confidence: 99%

“… Comparisons between the predicted and measured 30 temperature and species mole fractions at the oxidizer composition of 50% O 2 /50% He under hot NDF condition. …”

Section: Details Of the Numerical Simulationmentioning

confidence: 99%

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Comparative Study on the Dimethyl Ether Combustion Characteristics in Normal and Inverse Diffusion Spherical Flame Geometries

et al. 2020

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“…Studies on the flammability limit (FL) are of great significance because of their importance to fire safety, combustion efficiency, and pollutant emissions . With the increasing awareness of practical meanings of FL on combustion, continuous attention has been paid to the FL theories in the past few decades .…”

Section: Introductionmentioning

confidence: 99%

Flammability and Propagation Dynamics of Planar Freely Propagating Dimethyl Ether Premixed Flame

et al. 2020

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Flammability dynamics and physics play a crucial role in fire safety and combustion efficiency. This paper numerically studied the flammability dynamics of dimethyl ether/air freely propagating premixed flame over a broad range of equivalence ratios (ϕ). The results showed that the traditional flammability range should be redefined considering the impact of low-temperature chemistry. A physically stable warm-flame branch existed in the ultrarich region (ϕ = 7.58–12.59), which connected the hot and cool flame transition smoothly. However, in the lean region, the transition between hot and cool flames was completed by extinguishment or ignition. Sensitivity analysis was performed to reveal the governing chemical and diffusive processes for the flammability limits (FLs). In addition to the high-temperature reactions, low-temperature chemistry also played an important role in the lean hot-flame FL because of its double-flame structure. Heat conduction and fuel and oxygen diffusions were the most significant diffusive processes for the near-limit flame propagation. The near-limit flames had a diffusion-reaction structure, in which the flame front propagation was sustained by the heat conduction-induced ignition rather than the autoignition wave. The hot-flame extinction was induced by radiative extinguishment of the high-temperature propagating front embedded in the double-flame structure, and the cool-flame extinction was induced by excessive diffusive loss.

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Actualization of an efficient throttleable laser propulsion mode

Zhang

Duan

et al. 2021

Energy

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Study on flame structure and extinction mechanism of dimethyl ether spherical diffusion flames

Cited by 8 publications

References 39 publications

Comparative Study on the Dimethyl Ether Combustion Characteristics in Normal and Inverse Diffusion Spherical Flame Geometries

Comparative Study on the Dimethyl Ether Combustion Characteristics in Normal and Inverse Diffusion Spherical Flame Geometries

Flammability and Propagation Dynamics of Planar Freely Propagating Dimethyl Ether Premixed Flame

Actualization of an efficient throttleable laser propulsion mode

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