Numerical Simulation Of Exhaust System In Room-channel Underground Commercial Street

With the wide application of Room-channel structure in underground commercial building, the current regulations are not fine-grained enough for the exhaust system parameters design in room-channel structure. The influence of exhaust parameters interaction on exhaust effect does not reflected in current regulations. Therefore, it is imventant to research the effect of smoke exhaust system of underground commercial street in different parameter combinations.The special characteristics of room-channel structure of underground commercial street was analyzed. The length of channel is70-80m. The fire broke out in the room which characterized by limited combustion, and the layers of phenomenon and entrainment phenomenon is more apparent in the process of the spread of smoke. To obtain the fire load of high fire risk area between330-504MJ/m through investigation According to the norms of the theoretical analysis to the design method of smoke control system and the parameter design principle. Paper work including:Choose the FDS software which suitable for field simulation of smoke as the research method by comparative analysis on the applicable conditions of different simulation methods.Combined with the requirements of smoke zone area of not more than500m2, the farthest distance not more than40m from evacuation and some engineering parameters, build the physical model of a room with7.5m×6m×3m and a channel with80m×6m×3.2m. Changing of HRR with1MW of the indoor fire has little effect on the flue gas parameters in the channel based on the analysis of natural spread flue gas conditions in the channel under different HRR. According to the design code, determine the fire power of the4MW fire period.Set a fire in the room at the middle part of the channelas the most unfavorable fire scenarios. There are eight working conditions about exhaust vent arrangement and exhaust volume, and sixteen working conditions about air supply way and air supply ratio. The conclusion is, the influence on the effects of exhaust system from vent arrangement is more important than the influence from exhaust volume. The advantage of centralized arrangement increases with the increasing of exhaust volume, and exhaust volume is not more than72m3/(m2·h) at4MW fire period.The influence on smoke layer height and the lower smoke layer temperature in the channel from air supply way is very obviously.The distal air supply way has obvious advantages at50%air supply ratio compared with the uniform ventilation, and the50%air supply ratio is optimal.The conclusion has certain practical significance, which can provide reference for the exhaust system design and renovation of underground commercial street.