Figs. 6 and 7 show the smoke dispersion in the tunnel and shaft at the steady period of smoke movement under different HRRs and correspondently Figs. 8 and 9 show the velocity vector field in the shaft (the red1 arrow length represents the velocity magnitude and the black arrow shows the general flow track of smoke and air). It can be found that the smoke dispersion inside the tunnel is similar under different environmental wind speeds, and at a fixed wind speed, the smoke layer inside the tunnel under a higher HRR is thicker. Moreover, when the wind speed increases or the HRR decreases, the angle of smoke plume exhausted by the shaft becomes larger, as a result, the smoke dispersion amount near the opening of the shaft becomes less.