Abstract:

In this paper, based on the theory of fire dynamics，considering the influence of the thickness of the material and the position of the ignition source on the combustion process ，and a dimensionless fire spreading rate model of thermoplastic external thermal insulation material was established，and the  coupling combustion degree was proposed to characterize the mutual promotion between upward fire spread and downward melt flow combustion.By taking the thickness of the material and the position of the fire source as variables, the results show that the fire spreading rate of the thermoplastic external thermal insulation material increases exponentially with time, and the accuracy of the model is verified, and the coupling degree of combustion under different thickness and different position of ignition source was obtained，and the results show that the coupling combustion degree is proportional to the growth rate of fire spread.

Key words:  , thermoplastic external thermal insulation material,  , rate of fire spread,  , thickness of the material and the position of the ignition source, melt and flow, coupling combustion degree