Visualizing experiment of smoke filling processes in underground long and narrow enclosed space

The experiment results show that smoke fills from top down to bottom when the model shape coefficient is less than 2 and the interface of smoke layer is horizontal, and that the long and narrow enclosed space smoke filling mode will be formed when the shape coefficient is equal or greater than 2, and it is more obvious with even larger shape coefficient. The distribution characteristics of smoke density in the two modes are different. When the shape coefficient is less than 2, the distribution of smoke density on the same horizontal plane is relatively uniform, while that is very non uniform when the shape coefficient is equal or greater than 2, the smoke density far away from the fire source is far higher than that near the fire source. The smoke filling mode in a long and narrow enclosed space is unfavorable for human evacuation under fire, so it should be considered fully when the fire evacuation plan was drafted for underground spaces.