Flame Propagation over Energized Pe-Insulated Wire Under Low Pressure

Flame Propagation over Energized Pe-Insulated Wire Under Low Pressure

H. He Q.X. Zhang L.Y. Zhao J. Liu J.J. Wang Y.M. Zhang

State Key Laboratory of Fire Science, University of Science and Technology of China, P. R. China

| |
| | Citation



Flame spread along the energized polyethylene (PE) insulated copper wire under low pressure was investigated experimentally to gain a better understanding of electrical wire fire in aircraft and space habitats. Three types of sample wires, with the same insulation thickness and different core diameters, were used in this research study. First, a simplified model was developed to quantitatively explain the impact of lower pressure on the flame propagation over the energized wires. As with the pressure decreased, both of Grashof number (Gr) and Reynolds number (Re) were decreased and the air-flow diffusion played a gradual and dominant role in the combustion process. Mainly caused by the decrease of natural convention, the heat loss turned to be reduced, resulting in the reduction of oxygen flow and the formation of carbon black was inhibited. Second, several experiments were conducted to investigate the flame spread along the energized wires in a walk-in hypobaric chamber. The experimental results showed that, with the decrease of pressure, the flame height was reduced, the flame shape turned to be spherical, and the blue area showed increased. But the flame shape was reduced gradually along the wire, till extinguished when the pressure set out below a critical value. The accumulation of melt insulation increased and the dripping behavior occurred easily under lower pressure. Moreover, the influence of overload current on the flame spreading velocity was also presented. This work was useful for a further study on the fire risk of electrical wires under low pressure.


electrical wire, flame propagation, flame spread, low pressure, overload current


[1] Jia, F., Patel, M.K., Galea, E.R., Grandison, A. & Ewer, J., CFD fire simulation of the Swissair flight 111 in-flight fire-Part 1: Prediction of the pre-fire air flow within the cockpit and surrounding areas. Aeronautical Journal, 110(1103), pp. 41–52, 2006. http://dx.doi.org/10.1017/S0001924000004358

[2] Hirschler, M.M., Survey of fire testing of electrical cables. Fire and Materials, 16(3), pp. 107–118, 1992. http://dx.doi.org/10.1002/fam.810160302

[3] Kikuchi, M., Fujita, O., Ito, K., Sato, A. & Sakuraya, T., Experimental study on flame spread over wire insulation in microgravity. Symposium (International) on Combustion, 27(2), pp. 2507–2514, 1998. http://dx.doi.org/10.1016/s0082-0784(98)80102-1

[4] Fujita, O., Nishizawa, K. & Ito, K., Effect of low external flow on flame spread over polyethylene-insulated wire in microgravity. Proceedings of the Combustion Institute, 29(2), pp. 2545–2552, 2002. http://dx.doi.org/10.1016/S1540-7489(02)80310-8

[5] Nakamura, Y., Yoshimura, N., Ito, H., Azumaya, K. & Fujita, O., Flame spread over electric wire in sub-atmospheric pressure. Proceedings of the Combustion Institute, 32(2), pp. 2559–2566, 2009. http://dx.doi.org/10.1016/j.proci.2008.06.146

[6] Fujita, O., Kyono, T., Kido, Y., Ito, H. & Nakamura, Y., Ignition of electrical wire insulation with short-term excess electric current in microgravity. Proceedings of the Combustion Institute, 33(2), pp. 2617–2623, 2011. http://dx.doi.org/10.1016/j.proci.2010.06.123

[7] Huang, X., Nakamura, Y. & Williams, F.A., Ignition-to-spread transition of externally heated electrical wire. Proceedings of the Combustion Institute, 34(2), pp. 2505–2512, 2013. http://dx.doi.org/10.1016/j.proci.2012.06.047

[8] Nakamura, Y., Yoshimura, N., Matsumura, T., Ito, H. & Fujita, O., Flame spread over polymer-insulated wire in sub-atmospheric pressure: Similarity to microgravity phenomena. Progress in Scale Modeling, pp. 17–27, 2008.

[9] Hu, L., Zhang, Y., Yoshioka, K., Izumo, H. & Fujita, O., Flame spread over electric wire with high thermal conductivity metal core at different inclinations. Proceedings of the Combustion Institute, 35(3), pp. 2607–2614, 2015. http://dx.doi.org/10.1016/j.proci.2014.05.059

[10] Cahill, P., Electrical short circuit and current overload tests on aircraft wiring. Federal Aviation Administration Technical Center Atlantic City NJ, No. DOT/FAA/CT-TN94/55, 1995.

[11] Babrauskas, V., Mechanisms and modes for ignition of low-voltage PVC wires, cables, and cords. Fire & Materials, pp. 291–309, 2005.

[12] Bergman, T.L., Lavine, A.S., Frank, P., Incropera, F.P. & Dewitt, D.P., Fundamentals of Heat and Mass Transfer, John Wiley & Sons, pp. 407–408, 2011.

[13] Tsubouchi, T., Heat transfer from fine wires and particles by natural convection. Reports of the Institute of High Speed Mechanics, Tohoku University, 12, 1961.

[14] Faraday, M., The chemical history of a candle. Resonance, 7(3), pp. 90–98, 2002. http://dx.doi.org/10.1007/BF02896314

[15] Warnatz, J., Maas, U. & Dibble, R.W., Combustion: physical and chemical fundamentals, modeling and simulation, experiments, pollutant formation, 2006.