Studies on internal fire whirls in a vertical shaft with a single corner gap

Internal fire whirls in a vertical square channel were studied experimentally in a vertical square channel of size 2 m by 2 m and height 15 m. Onsetting of fire whirl at different ventilation conditions at the shaft bottom was studied. Some of the experimental scenarios under different ventilations were simulated numerically using Computational Fluid Dynamics (CFD) with large eddy simulation. Predicted results were applied to justify the experimental observations. The bottom vent size was identified to be important in onsetting internal fire whirls. Air temperature and velocity profiles at center measured and predicted were compared. From the experimental observations and associated numerical experiments, it is further verified that the single corner gap is the key factor in generating a stable fire whirl in a vertical channel. Further, axis of the whirling fire would be shifted toward the side wall.