Numerical Simulation Of Ventilation And Smoke Exhaust Of Special Long Highway Tunnel Based On CFD

Due to its narrow and narrow building structure,the extra-long road tunnel makes it difficult to effectively discharge pollutants in the tunnel for a long time,thus affecting the health and safety of tunnel personnel.Although the tunnel fire is not a frequent incident,once it occurs,it will cause irreparable damage to the tunnel personnel safety and social economy.On the one hand,the toxic fumes generated by fire will threaten people's life and health;on the other hand,the high temperature heat generated by the fire will destroy many auxiliary electromechanical facilities of the tunnel.In severe cases,the wall lining structure will be destroyed,and there is a greater potential safety hazard.Therefore,the use of effective and reasonable ventilation and smoke extraction methods can not only improve the ventilation and smoke exhaustion effect,increase the safety and comfort of tunnel personnel,but also greatly save energy and reduce the probability of secondary accidents.Exhaust smoke has important practical significance.Based on the existing theoretical research results of tunnel ventilation and smoke exhaust at home and abroad,this paper takes the extra-long highway tunnel as the research object,and analyze the characteristics of ventilation and smoke exhaust in extra-long tunnels with independent exhaust ducts.Through theoretical analysis and the use of CFD software,a three-dimensional model of tunnel ventilation and smoke extraction is established,and the numerical simulation of tunnel ventilation and smoke exhaust is carried out based on the theoretical knowledge of tunnel ventilation and smoke exhaust.In the aspect of ventilation,the standard turbulence model and SIMPLE solution method of CFD software solver are used to study the action law of the jet fan in the tunnel,the influence of natural wind on the range of the fan under flue system,and through the comparative analysis,it demonstrates the advantages of the ventilation effect of the tunnel fan when the exhaust duct is installed;in the aspect of fire smoke,the fire solving model of the CFD is used to simulate the smoke emission characteristics of the tunnel with independent exhaust ducts,and the fire temperature in the horizontal and vertical sections is analyzed and discussed.The law of distribution,then simulation and comparison,under the effect of free fire propagation and critical wind speed of tunnel fire,compare the analysis of the smoke exhausting effect of the flue-discharging and non-exhaust flue,and finally put forward the fire control strategy of the extra-long tunnel fire with flue.The results show that the ventilation and smoke exhaust under the new mode,which is the extra-long road tunnel with exhaust duct at the top,it shows a certain advantage compared with the traditional single longitudinal ventilation method of the tunnel.This provides more time and possibility for special road tunnel fire rescue.