Experimental investigation on the characteristics and propagation of fire inside subway train

With the rapid development of subway systems, the related fundamental knowledge is critically needed to benefit their designs and fire hazard assessment. The experimental study was performed in a 1/5th scale subway train model to characterize the fire inside subway train, and the experiment in open space was also conducted as a control group. Results show that in the case where the ceiling flame has not yet propagated to the sidewalls of the subway train, the normalized ceiling flame length varies as 1/4 power of the non-dimensional ceiling heat release rate. In addition, the temperature distributions at different transverse distances from the fire source follow the exponential decay law effectively, the decay rate is indeed a function of normalized transverse distance from the longitudinal centerline. An empirical model involving dimensionless transverse and longitudinal coordinates is proposed to predict the two-dimensional temperature underneath the ceiling, which is reasonably well fitting with experimental results from this study and literatures.