Simulating study on descent character of hot smoke under sprinkler spray and fire source with decreasing HRR

Varying the flow rate of sprinkler developed the spray model.The HRR of the fire source was modified by the Tamanini formula.Numerical simulation was performed to investigate the layer height of hot smoke and the development of the HRR under sprinkler spray.Based on the simulation result,the effect of the spray and the fire source on the descent characteristics of the hot smoke was analyzed.The driving force of the smoke descent was concluded by comparing the developments of the layer height under different fire source conditions.The study shows that increasing the flow of the sprinkler,the decay extent of the HRR decreases,and that the descent region extends and the layer height decreases with the enhancement of the descent effect on the hot smoke of the spray.The smoke descent results from the synergistic effect of the descent effect of the spray and the buoyant effect of the smoke layer.The layer height decreases with the decrease of the HRR after the occurrence of smoke descent arising.