Study on downward flame spread behavior of flexible polyurethane board in external heat flux

Abstract

In this work, the downward flame spread of flame of flexible polyurethane (FPU) foam with a different width was studied in an external radiant heat source. The effects of external radiation heat flux on the main parameters of flame spread, such as the flame height, mass loss rate, flame spread rate and flame pulsation frequency were investigated. The experimental results show that the flame spread of the FPU is an accelerating process when there is an external radiation condition and is a steady one without it. As the flame spread over board, the amount of pyrolysis gases involved in the combustion process showed a positive relationship with the external radiation heat flux. The flame height is under a combined effect of width and external radiation heat flux. However, the flame pulsation frequency shows a negative correlation with the fuel width and the radiation heat flux. Finally, an empirical equation approximation of linear pool fire is introduced to analyze the flame spread behavior of FPU as well as the validation with experiment data.