Effects of electric field intensity and distribution on flame propagation speed of CH4/O2/N2 flames

Duan, Hao; Wu, Xiaomin; Sun, Tao; Liu, Bing; Fang, Jianfeng; Li, Chao; Gao, Zhongquan

doi:10.1016/j.fuel.2015.05.065

Cited by 20 publications

(7 citation statements)

References 30 publications

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“…Previous studies [30,31,38] have verified that our electrode arrangement could only produce an approximately uniform electric field between the ignition and the mesh electrode, and a u was about 0.7 in the main study zone for −2.5 kV and −5 kV electric field.…”

Section: Governing Equationssupporting

confidence: 52%

“…The external systems for the two experiments were the same as what was used in the past [27,30,31], and consisted of six parts, including a constant-volume combustion chamber system, a fuel supply, an ignition control circle, an optical Schlieren system, a high-speed camera and a high-voltage supply system, as shown in Figure 1.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…In Figure 8, it can be seen that the ionic signal will be obtained only when the flame surface reaches the Langmuir probe, because the major ions were mainly formed on the flame surface. The power supply for the Langmuir probe was a constant, so the ionic signal could directly reflect the ionic concentration at the measuring point, and the peak value of the ionic signal represents the peak ionic concentration [31]. Figure 8a,b shows that when the electric field was not loaded, the peak value of the ionic signal at the center and the side position (Points 1-4) were all near 0.3 V, which means the ionic concentration distribution was almost uniform on the flame surface without the electric field.…”

Section: Ionic Concentration Distributionmentioning

confidence: 99%

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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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Section: Governing Equationssupporting

confidence: 52%

Section: Experimental Apparatusmentioning

confidence: 99%

Section: Ionic Concentration Distributionmentioning

confidence: 99%

See 1 more Smart Citation

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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“…T HE ability of electric fields to modify flames is well known and has been the subject of research for both premixed and diffusion flames [1][2][3][4][5]. The effect of electric fields on flames has been investigated through experiments and simulations, and the results showed that the field can increase flame blowoff limits at fuel-lean conditions [4,[6][7][8], increased flame burning velocity [3,9,10], decreased emissions and soot formation [11][12][13][14][15], and enhanced flame stability [3,8,16,17]. The possible application of electric fields to control the flame transfer function and thermoacoustic instabilities has also been suggested [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…The theory is that collisions between neutrals and accelerated electrons and ions promote dissociation of the neutral molecules and dissociative recombination of ions to create radical species such as H and OH that promote combustion. Enhancement of the laminar flame velocity, which is typically a chemical property, in combustion bomb experiments indicates that the field does affect the flame speed and thus chemistry, though the exact process is yet unknown [9,10]. Wisman et al [20][21][22] conducted experiments with conical flames and proposed that the electric field causes thermodiffusive instabilities through a combination of changes in the flame chemistry from ion dissociative recombination reactions and reduction of the Lewis number.…”

Section: Introductionmentioning

confidence: 99%

Electric Field Modified Bunsen Flame with Variable Anode Placement

Salvador

2017

Journal of Thermophysics and Heat Transfer

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A methane-air Bunsen flame was tested under dc electric field forcing with different ring anode sizes and locations. The anodes were placed within the flame to far outside the flame, both axially and radially. The focus of the work is to understand the limit of electrode placement and its effect on the flame under a dc field. A stoichiometric flame with voltages up to 9.1 kV was tested. The electrical current and flame height were measured as a function of the bias voltage and anode location. Plasma density measurements of the unmodified flame at various axial locations were used to corroborate that anode placement at regions of high electron density caused the largest reductions in flame height. The results showed the anodes closest to the burner at 35 mm caused the largest reduction (24%) in flame height. The effect of the electric field on flame height decreased as the anode moved farther downstream of the flame or radially outward. For the same voltage, larger currents were also observed for anodes close to the burner, whereas anodes placed far outside of the flame had minimal effects on current and, consequently, on the flame height. These differences are due to the variable electron density at the anode, which limits the net current collected and the strength of the field.

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Recent progress in electric-field assisted combustion: a brief review

Liu

Cai

2021

Front. Energy

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Effects of electric field intensity and distribution on flame propagation speed of CH4/O2/N2 flames

Cited by 20 publications

References 30 publications

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

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

Electric Field Modified Bunsen Flame with Variable Anode Placement

Recent progress in electric-field assisted combustion: a brief review

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