Numerical study on flame spread in cabin atmosphere under various overloads

The aircraft cabin is special confined space with various overloads during motion, whose effect on fires is not clear yet. To understand the fire behaviours at different overloads in cabin atmosphere, numerical simulation was performed on upward flame spread over thin solids by solving the governing equations of both gas and solid phase. The main parameter is the overloads and 0g to 2g was considered. At most overloads, the flame accelerates and grows continuously before extinction while at 0g, flame propagates only with imposed flow. The transient flame positions and spread rates was compared against the overloads and mathematical correlations were proposed. To further understand the effect of overloads on fire behaviours, the local flow speed, solid temperature and heat flux were studied in detail. With the increase of the overloads, the induced flow due to buoyancy increased significantly, which enhanced the oxygen transfer to the flame and heat transfer to the solids. As a consequence, both the gaseous reaction and solid pyrolysis was stimulated, which resulted in longer flame and faster spread rate. The results in this paper revealed that fire safety concern is more serious at high overloads and can contribute to the fire protection design in aircrafts.