Numerical prediction of ion current from a small methane jet flame

Yamashita, Kiyotaka; Karnani, Sunny; Dunn‐Rankin, Derek

doi:10.1016/j.combustflame.2009.02.002

Cited by 51 publications

(30 citation statements)

References 12 publications

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“…Typically, when an external DC field is applied, an electric current from a flame increases with the DC field [21,22]; it becomes saturated with an excessive DC field exceeding a certain critical field intensity [23][24][25][26]. In the sub-saturated regime, space charges redistribute to minimize their potential, shielding the electric field and limiting the current, but in the saturated regime, no further space charges remain in the flame zone-all generated ions and electrons migrate toward their corresponding electrode.…”

Section: Introductionmentioning

confidence: 99%

DC field response of one-dimensional flames using an ionized layer model

Xiong

Park

Lee

et al. 2016

Combustion and Flame

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Abstract:We develop a simplified model to better explain electric current response when direct current (DC) is applied to a flame. In particular, different current responses have been observed by changing the polarity of the DC in a sub-saturated current regime that results from the presence of ions and electrons in the flame zone. A flame zone was modeled as a thin, ionized layer located in one-dimensional DC electric fields. We derived simplified model-governing equations from species equations by implementing mobility differences dependent on the type of charged particle, particularly between ions and electrons; we performed experiments to substantiate the model. Results showed that the sub-saturated current and local field intensity were significantly influenced by the polarity of the DC because of the combined effect of unequal mobility of charged particles and the position of the ionized layer in the gap relative to two electrodes. When an energized electrode is close to the ionized layer, applying a negative DC causes a more rapid increase in current than by applying a positive DC to the same electrode.Results from our experimental measurement of current using counterflow diffusion flames agreed qualitatively well with the model predictions. A sensitivity analysis using dimensional and non-dimensional parameters also supported the importance of the mobility difference and the relative location of the ionized layer on the electric current response.

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Section: Introductionmentioning

confidence: 99%

DC field response of one-dimensional flames using an ionized layer model

Xiong

Park

Lee

et al. 2016

Combustion and Flame

View full text Add to dashboard Cite

show abstract

“…Significant efforts have been made to study the effects of externally applied electric fields on the combustion process. In those studies, various types of flames have been studied, such as Bunsen flame [1][2][3][4], jet flame [5,6], flat flame [7], tribrachial flow flame [8], etc. Meanwhile, both direct current (DC) [9][10][11][12][13][14][15][16] and alternating-current (AC) [17][18][19][20][21] electric fields have been utilized.…”

Section: Introductionmentioning

confidence: 99%

Effects of Electric Fields on the Combustion Characteristics of Lean Burn Methane-Air Mixtures

Fang

Duan

et al. 2015

Energies

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Abstract:In this work, the effects of the electric fields on the flame propagation and combustion characteristics of lean premixed methane-air mixtures were experimentally investigated in a constant volume chamber. Results show that the flame front is remarkably stretched by the applied electric field, the stretched flame propagation velocity and the average flame propagation velocity are all accelerated significantly as the input voltage increases. This indicates that the applied electric field can augment the stretch in flame, and the result is more obvious for leaner mixture. According to the analyses of the combustion pressure variation and the heat release rate, the peak combustion pressure Pmax increases and its appearance time tp is advanced with the increase of the input voltage. For the mixture of λ = 1.6 at the input voltage of −12 kV, Pmax increases by almost 12.3%, and tp is advanced by almost 31.4%, compared to the case of without electric fields. In addition, the normalized mass burning rate and the accumulated mass fraction burned are all enhanced substantially, and the flame development duration and the rapid burning duration are remarkably reduced with the increase of the input voltage, and again, the influence of electric field is more profound for leaner mixtures. The results can be explained by the electric field-induced stretch effects on lean burn methane-air mixture. OPEN ACCESSEnergies 2015, 8 2588

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“…Meanwhile, the impact of electrons in this model is also small, because the applied voltages on the mesh electrodes are negative in this paper, so the direction of the electric field was from the ignition electrodes to the mesh electrodes (to the right in the simulation part of Figure 4). For this reason, only positive ions were driven to the premixed zone to produce the ionic wind effect, while electrons would be removed to the burned zone rapidly, due to their low number density and extremely high mobility (K = 4000 cm 2 /s/V) [36], which is at least three orders of magnitude higher than that of ions (K = 1.0 cm 2 /s/V) [28,37]. Although some research had shown that electrons may produce the excitation of nitrogen and other molecules by collisions [19,20], however, these chemical activation steps ocurred in the burned zones in this paper, so they would not have an obvious effect on the outward flame propagation.…”

Section: Numerical Assumptionmentioning

confidence: 99%

Deformation Study of Lean Methane-Air Premixed Spherically Expanding Flames under a Negative Direct Current Electric Field

et al. 2016

Energies

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This paper compares numerical simulations with experiments to study the deformation of lean premixed spherically expanding flames under a negative direct current (DC) electric field. The experiments, including the flame deformation and the ionic distribution on the flame surface were investigated in a mesh to mesh electric field. Besides, a numerical model of adding an electric body force to the positive ions on the flame surface was also established to perform a relevant simulation. Results show that the spherical flame will acquire an elliptical shape with a marked flame stretch in the horizontal direction and a slight inhibition in the vertical direction under a negative DC electric field. Meanwhile, a non-uniform ionic distribution on the flame surface was also detected by the Langmuir probe. The simulation results from the numerical model show good agreement with experimental data. According to the velocity field analysis in simulation, it was found the particular motion of positive ions and neutral molecules on the flame surface should be responsible for the special flame deformation. When a negative DC electric field was applied, the majority of positive ions and colliding neutral molecules will form an ionic flow along the flame surface by a superposition of the electric field force and the aerodynamic drag. The ionic flow was not uniform and mainly formed on the upper and lower sides, so it will lead to a non-uniform ionic distribution along the flame surface. What's more, this ionic flow will also induce two vortexes both inside and outside of the flame surface due to viscosity effects. The external vortexes could produce an entraining effect on the premixed gas and take away the heat from the flame surface by forced convection, and then suppress the flame propagation in the vertical direction, while, the inner vortexes would scroll the burned zones and induce an inward flow at the horizontal center, which could be the reason for the pitted structure at the horizontal center when a high voltage was applied.

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Numerical prediction of ion current from a small methane jet flame

Cited by 51 publications

References 12 publications

DC field response of one-dimensional flames using an ionized layer model

DC field response of one-dimensional flames using an ionized layer model

Effects of Electric Fields on the Combustion Characteristics of Lean Burn Methane-Air Mixtures

Deformation Study of Lean Methane-Air Premixed Spherically Expanding Flames under a Negative Direct Current Electric Field

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