Flame spread over inclined electrical wires with AC electric fields

Lim, Seung Jae; Park, Sun H.; Park, Jeong; Fujita, Osamu; Keel, Sang In; Chung, Suk Ho

doi:10.1016/j.combustflame.2017.07.010

Cited by 38 publications

(38 citation statements)

References 26 publications

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“…2 . This process can be attributed to the electrospray phenomenon, which has been observed previously for single-wire experiments [23] . A small droplet simultaneously detaches from the main body of molten PE and moves toward the burnt wire [SM 1], driven by the di-electrophoresis phenomenon [24] .…”

Section: Overall Flame Spread Behaviorsupporting

confidence: 63%

“…In this work, we study flame spread over twin electrical wires with direct current (DC) electric fields applied to suppress time varying potential in AC, and we describe in detail the interaction between two spreading flames. Note that DC has minimal effect on flame spread for the single wire configuration [21][22][23][24] , however as will be shown later, DC has significant effect for the present twin wire configuration. We used PE insulated electrical wires because these types of wires have been investigated extensively for understanding the fundamental physics of wire fires [3,5 , 3-17,21-24] .…”

Section: Introductionmentioning

confidence: 97%

“…A limited number of studies have been conducted on the effect of electric fields on a spreading flame over electrical wires [21][22][23][24] , and has shown that a spreading flame over electrical wires that were either inclined [23] or installed horizontally [21,22,24] was sensitive to the alternating current (AC) electric field applied to the wire. These studies showed that when AC electrical fields were applied to polyethylene (PE)-insulated electrical wires, several molten-PE-related phenomena were observed.…”

Section: Introductionmentioning

confidence: 99%

“…[22] . The formation of a globular molten PE in front of a downward spreading flame led to the extinction of the flame, while multiple small droplets from the main flame were ejected due to an electrospray phenomenon [23,24] . Such phenomena can be important when judging the safety of an electrical wire, especially in cases, for example, when outdoor power lines with several hundred kVs cross forested and agricultural areas via a transmission tower, presenting a high risk of widespread fire [25,26] .…”

Section: Introductionmentioning

confidence: 99%

“…A spacecraft is designed to supply power for analyzers, spectroscopes, and cameras with DC voltages of ∼5 kV and even 15 kV for space borne radar systems used for ground observations [27] . Whereas previous studies have examined flame spread over a single electrical wire only [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][21][22][23][24] , most electrical wiring involves paired wires with various electrical potentials.…”

Section: Introductionmentioning

confidence: 99%

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Flame spread over twin electrical wires with applied DC electric fields

Park

Kang

Suk

et al. 2019

Combustion and Flame

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a b s t r a c tThe effect of DC electric field on the characteristics of flame spread over polyethylene-insulated twin electrical wires was studied by varying wire gap ( S ) and voltage ( V DC ). Under an applied electric field, the flame spread rate (FSR), flame width, leaning direction of the interacting twin flames varied substantially with varying the voltage and wire gap. The flame spread rate was initially larger for the wire with negative voltage (spreading flame with negative charge; SF −) than the wire with positive voltage (SF + ), but the two eventually became the same in the developed region when a quasi-steady state was reached. The FSR behavior could be classified into two regimes; twin flame spread (regime I) and single flame spread (regime II) after the extinction of SF + . Under regime I, three sub-regimes were identified depending on the wire gap and voltage. For the twin flame spread, the flame spread rate initially decreased with increasing voltage as the flame leaned toward the burnt wire. As the two flames interacted, the flame spread rate increased because of the ionic wind effect, and eventually decreased because of the loss of molten PE mass and the electrospray phenomenon. In regime II after the extinction of SF + , the single flame spread showed a transient behavior since the influences of electric field from burnt and unburned wire sections of SF + wire varied with flame spread. When the voltage was increased even further, SF-was extinguished by streamer generation and, at excessive voltages, an electrical short occurred. The flame spread rates for twin flame spread were best correlated with the electric field intensity in the form of | V DC | 0.91 / S 0.72 .

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Section: Overall Flame Spread Behaviorsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flame spread over twin electrical wires with applied DC electric fields

Park

Kang

Suk

et al. 2019

Combustion and Flame

Self Cite

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Melt dripping behavior in the process of flame spread over energized electrical wire at different pressures

Wang

Wei

et al. 2019

Fire and Materials

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SummaryMelt dripping of polymer insulation in electrical wires is impacted by some factors, such as ambient pressure and electric current. The motivation of this paper is to investigate and discuss the effect of these factors on melt dripping characteristics in the process of flame spread over electrical wire. The results show that the number of dripping times and dripping frequency generally increase with ambient pressure reduced. No dripping phenomenon occurs when the ambient pressure is below 40 kPa at any electric current or is above 70 kPa without electric current applied. There is a good parabolic correlation between the ambient pressure and dripping frequency. The equilibrium temperature of conductor resulted by electric current increases with electric current. A critical electric current found to divide the temperature rate into two regimes is about 8 A. The dripping period and dripping frequency depend on the electric current. The dripping frequency fits well with electric current using a power‐law function. The numerical data are consistent with the experimental data. Besides, the decrease in dripping frequency is greater with ambient pressure at reduced electric current, whereas at larger electric current, the electric current, rather than the ambient pressure, dominates the increased dripping frequency.

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New Approach to Assessment of Fire Hazards of Electrical Cables

Martinka

2022

SpringerBriefs in Fire

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Flame spread over inclined electrical wires with AC electric fields

Cited by 38 publications

References 26 publications

Flame spread over twin electrical wires with applied DC electric fields

Flame spread over twin electrical wires with applied DC electric fields

Melt dripping behavior in the process of flame spread over energized electrical wire at different pressures

New Approach to Assessment of Fire Hazards of Electrical Cables

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