Creeping flame spread along fuel cylinders in forced and natural flows and microgravity

Delichatsios, Michael; Altenkirch, Robert A.; Bundy, Matthew F.; Bhattacharjee, Subrata; Tang, Lin; Sacksteder, Kurt R.

doi:10.1016/s0082-0784(00)80706-7

Cited by 45 publications

(25 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This trend differs from what is found with polymer rod done by Delichatsios et al (11) , showing that an increase in opposed flow speed gives higher spread rate. This implies that the wire could play as "heat sink" in the present system; the wire always sucks the heat from the flame.…”

Section: Discussioncontrasting

confidence: 97%

“…Yang et al (8) have examined the burning characteristics of (small) polymer sphere with various pressure conditions including sub-atmospheric range under the reduced gravity conditions and found nearly constant in burning rate under low pressure. On the contrary, there are other evidences (9)- (11) showing that the flame spread is promoted with the pressure drop. Naturally one simple question arises; whether the fire chance from the wiring increases or decreases in sub-atmospheric pressure?…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Opposed-wind Effect on Flame Spread of Electric Wire in Sub-atmospheric Pressure

Nakamura

Yoshimura

Matsumura

et al. 2008

JTST

View full text Add to dashboard Cite

Opposed flame spread of electric wire in sub-atmospheric pressure is studied experimentally. Thin-polyethylene (PE) coated nickel-chrome (NiCr) and iron (Fe) wire are used as test samples in this study. Total pressure is reduced from atmospheric (100 kPa) to sub-atmospheric (40 kPa) and range of employed external forced-flow speed is from 0 cm/s to 40 cm/s. Results show that the spread rate monotonically decreases, or stays nearly constant, as the forced-flow speed increases regardless of the material of the wire. Dependence of the spread rate on the opposed-flow speed appears differently depending on the material of the wire; with high-conductive material (Fe), decrement trend of the spread rate with wind is suppressed. Importantly, under the conditions considered in this study, the spread rate tends to increase as the pressure decreases regardless of the pressure and the material of the wire. Dependence of the spread rate on pressure is more pronounced with less-conductive (NiCr) wire, whereas less-pronounced with high-conductive (Fe) wire. Qualitative discussions are made to explain the observed spread trend and the importance of the presence of wire to characterize the flame spread of the wire is addressed.

show abstract

Section: Discussioncontrasting

confidence: 97%

Section: Introductionmentioning

confidence: 96%

Opposed-wind Effect on Flame Spread of Electric Wire in Sub-atmospheric Pressure

Nakamura

Yoshimura

Matsumura

et al. 2008

JTST

View full text Add to dashboard Cite

show abstract

“…The flame heats the insulation and the conductor mainly by convection [23,24]. The heats transferred from the flame to the conductor and from the flame to the insulation are …”

Section: Steady-state Flame Propagation Modelmentioning

confidence: 99%

Ignition and Flame Propagation of Externally Heated Electrical Wires with Electric Currents

Wang

Zhao

et al. 2015

Fire Technol

View full text Add to dashboard Cite

This paper describes the results of an experimental and numerical study of the effect of electric current on the ignition and flame propagation propensity of polyethylene-insulated copper conductor electrical wire. Two simplified models were developed to describe the ignition and steady flame propagation of energized electrical wires exposed to an external heat flux, respectively. The models predict that for a higher-conductance wire it is more difficult to achieve ignition and flame propagation. Experiments were performed on three types of electrical wires with different conductor diameter of 0.5 mm, 0.8 mm and 1.1 mm and the same insulation thickness of 0.15 mm. A 20 mm long coil heater was used as the ignition source to generate a controlled heat flux. Experiments show that increasing the current of wire leads to a convexly decreasing critical heat flux for ignition, agreeing with model predictions. Effects of different currents on insulation temperature and flame height are discussed. The flame width of three types of wires could be considered invariable with the current, which are 9.06 mm, 12.45 mm and 15.07 mm respectively. The heat release rate of flame is discussed through the volume of flame and a correlation is presented that DV F µ I 2 . The likelihood for molten PE dripping is determined by the absolute and relative fuel load for different wires. Finally, the correlation between the flame propagation velocity and the current of wire, Dv f µ I 2 , is demonstrated.

show abstract

“…To better understand the heat transfer mechanism, Figure demonstrates the side view, front view, and end view of the flame shape for cylindrical fuel schematically. Actually, comparing with flat fuel with the same thickness, energy transferred from flame to solid surface for cylindrical fuel is increased because of a higher heat transfer coefficient, and the required heat for pyrolysis of solid is decreased because the flame is convex …”

Section: Resultsmentioning

confidence: 99%

“…Fernandez‐Pello et al studied the flame spread along cylindrical rods and investigated the mechanism of heat transfer associated with the rod diameter. What is more, Delichatsios et al performed experiments of creeping flame spread along cylinders and developed a semi‐analytical expression to predict flame spread rate for cylindrical surfaces. Their work included pressures of 1 and 2 atm, and the results showed that flame spread velocity in pressure of 2 atm was higher than that in normal pressure.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on flame spread along fuel cylinders in high pressures

et al. 2019

View full text Add to dashboard Cite

Summary Flame spread over solid fuels in high‐pressure situations, such as nuclear containment shells during a pressurized period, has potential to result in catastrophic disaster, thus requiring further knowledge. This paper experimentally reveals the flame spread behaviors over fuel cylinders in high pressures. Polyethylene and polymethyl‐methacrylate cylinders with the diameter of 4.0 mm are used in this study. Ambient gas is air, and total pressures are varied from naturally normal pressure (100 kPa) to elevated pressure (500 kPa). Flame characteristics including flame appearance and flame size and burning rate and flame spread rate are investigated. Results show that in high pressure, the flame appearance is significantly affected. As the pressure increases, the blue flame disappeared, and the color of flame tip changes from luminous yellow to orange as well the orange part extends down towards the base of flame. The dimensionless flame height increases with pressure for pressure below 150 kPa and then decreases with pressure above that level. The burning rates show increasing trend with pressure and are proportional to P0.6 and P0.79 for polymethyl‐methacrylate and polyethylene, respectively. Besides, flame spread rates for polymethyl‐methacrylate and polyethylene both were found to be proportional to P0.5.

show abstract

Creeping flame spread along fuel cylinders in forced and natural flows and microgravity

Cited by 45 publications

References 17 publications

Opposed-wind Effect on Flame Spread of Electric Wire in Sub-atmospheric Pressure

Opposed-wind Effect on Flame Spread of Electric Wire in Sub-atmospheric Pressure

Ignition and Flame Propagation of Externally Heated Electrical Wires with Electric Currents

Experimental study on flame spread along fuel cylinders in high pressures

Contact Info

Product

Resources

About