Study on mechanism of increased fire spread rate of suspended cables

doi:10.16265/j.cnki.issn1003-3033.2025.11.0453

Abstract

Abstract:

In order to clarify the influence of droop angle on suspended cable fire spread characteristics, a cable combustion test platform was constructed. The cable combustion tests with different droop angles (θ) and different cross-sectional areas (S) were carried out. The results show that the flame presents an axisymmetric conical state when the cable is arranged horizontally. When the droop angle is greater than 0°, as the combustion progresses, the flame shape transits from a multi-branched cone to an extended state along the cable direction. The flame spread behavior of cable can be divided into three stages: the advance of the pyrolysis front in stage I increases FSR, the interaction between thermal convection and thermal radiation in stage II leads to a rapid increase of FSR. Stage III thermal radiation dominates the continuous increase of FSR. The radiation heat flux generated by combustion plays a leading role in the increase of FSR. The rapid increase of radiation heat flux and the appearance of peak value are consistent with the three stages of fire spread, which can be used as a sign of the increase stage. The increase of θ and the decrease of S will promote the increase of FSR. According to the Stephen-Boltzmann law, the relationship between θ and S for the increase of FSR is proposed, and the theoretical index of the relationship is in good agreement with the experimental index.

Key words: suspended cable, flame spread rate (FSR), droop angle, cross-sectional area, heat flux

CLC Number:

X932爆炸安全与防火、防爆

PENG Wei, WANG Yiting, ZHANG Shaojie, REN Junsheng, ZHOU Yue, GU Heng. Study on mechanism of increased fire spread rate of suspended cables[J]. China Safety Science Journal, 2025, 35(11): 157-163.

Figures/Tables 9

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工况名称	S/mm²	θ/(°)
a₁―a₅	2.5, 4.0, 6.0, 10.0, 16.0	0
b₁―b₅		15
c₁―c₅		22.5
d₁―d₅		30
e₁―e₅		37.5
f₁―f₅		45
g₁―g₅		60