Simulation Study On Smoke Spread And Ventilation Of Underground Garage Fire

The development and use of underground space is the trend of urban development today.With the massive increase in the number of cars,the construction of underground garages has also increased year by year.In the case of the shortage of land resources on the ground,the construction of underground garages has brought convenience to people’s lives and work,and at the same time,it has also brought about fire hazards that cannot be ignored.Underground garage not only stores a large number of vehicles,but also arranges various pipeline,which leads to numerous cases of underground garage fire.Because there are few doors and windows in the underground garage and it is airtight,once there is a fire,the heat and toxic smoke are difficult to be discharged from the outside,and it is very difficult to escape and rescue.Therefore,it is very meaningful to study the smoke movement law of the underground garage fire.In this paper,a 1:1 three-dimensional underground garage model is established by using the Pyrosim numerical simulation software based on the field investigation of a university experimental complex building in Hefei and the collected CAD drawings,and the numerical research on the fire smoke spread and smoke exhaust ventilation of the underground garage is carried out.Seven working conditions are set up to analyze the movement law of smoke and the variation law of fire parameters such as visibility,temperature and CO concentration in underground garage from three aspects of fire source location,smoke exhaust speed and air supplement speed.The results show that:(1)From the simulation results of different fire source locations,it can be seen that the different fire source locations will have a significant impact on the smoke movement law of underground garage.Because the fire source is located at the corner and the side of the wall,it is limited by the wall.The smoke first accumulates on the wall and then spreads in one direction.The whole smoke prevention zone is not filled when the combustion time reaches 110 s,and the fire source is located in the garage In the central position,the smoke basically filled the whole smoke control zone in 110 s.Comprehensive comparison shows that when the fire source is located in the center of the garage,the temperature and CO concentration are relatively high,and the fire hazard is the largest,which is the most unfavorable fire source location.(2)Compared with natural exhaust,mechanical exhaust system can effectively reduce the smoke concentration and temperature in the garage.With the increase of smoke exhaust wind speed,a lot of smoke is discharged to the outside,and the smoke concentration in the garage is reduced.When the building space is fixed,the smoke exhaust speed can not be increased.When the smoke exhaust speed is 6m/s,the CO concentration in the garage is not much higher than 9m/s,and the overall temperature is about 70 ℃,which is lower than the smoke exhaust speed of 9m/s.therefore,the speed of the smoke exhaust fan has a boundary value,and the increase will have the opposite effect.(3)When the wind speed of the mechanical exhaust fan is fixed,adding an air supplement system can better dilute the CO concentration in the garage,but the effect on the temperature and visibility is not obvious.Figure[66] table[4] reference[51]...