| As one of the major dangers of loss of control in time and space,the fire brought great economic losses and casualties.The tunnel fire because of its unique spatial characteristics,in the event of tunnel smoke and away from the fire brigade and other reasons for the fire extinguishment caused a large extent.Water mist as an alternative to recent years,the emergence of alternative environmental fire extinguishing agent,rapid development,and other systems of linkage control makes the water mist in the effective time to suppress the fire,to control the further spread of fire.FLUENT obtains the spatial and temporal distribution of the characteristic parameters in the fire process by numerical solution of the partial differential equations of fire.It can simulate the process of the temperature and concentration of the flue gas in the fire,and provide the theory for the suppression of the fire help.Application of FLUENT to study the optimization of water mist design parameters and mechanical smoke control equipment linkage control is particularly important.In this paper,pentane and heptane were selected as fire source fuels.The non-premixed combustion model was used to study the changes of temperature and flue gas concentration in whole space under the conditions of single chamber and tunnel.The influence of different water mist flow,spray method,droplet size and exhaust method on the temperature field and concentration field in the fire field.(1)Compared with the data of the temperature of the fire source at the end of the fire source,the FLUENT is proved to be the reliability of the water mist fire suppression and the error reason is analyzed.On the basis of the comparison model,the ignition power is set to 60 Kw,and the simulation condition is changed.The conclusion is that when the particle size is 100?m,the water flow or the flow rate is constant,The increase of the mist flow rate or the flow rate will reduce the suppression time of the water mist to the fire,the flow rate or the flow rate of the same proportion,the flow rate will have the better effect than the flow rate.When changing the water droplet size of 300?m,The flow rate and the flow rate are found.The effect of the fine water mist on the fire source is lower than 100?m.In the side spray mode,the particle size is 100?m,the optimal flow rate and the flow velocity,the fire source is cooled by the water mist The effect is not strong,it is difficult to cool the fire room space fire.(2)Under the steady-state simulated road tunnel model,the influence of different water mist atomization cone angle on the temperature field of the fire space space is obtained.When the 90 ° water is obtained,the water mist is the best for the fire control effect.When used in conjunction with vertical smoke,the combination of smoke and water mist can effectively reduce the temperature of the fire and eliminate the toxic fumes.The effect is better than that of the application of fine water mist,but the exhaust wind speed will be smaller The water mist has a negative impact.(3)The influence of the coupling effect of different mechanical exhaust conditions and fine water mist on the temperature field and the flue gas concentration of the tunnel is simulated.The results show that the temperature field and the flue gas concentration of the tunnel smoke Of the control effect is better than the application of water mist alone,can reduce the thickness of the flue gas,but may produce flue gas reflux and temperature field vortex.The effect of vertical ventilation is better than the top of the smoke,the inlet side of the ventilation into the high temperature smoke in the case of thrust to the export side of the discharge,to prevent the smoke back,but will affect the movement of water droplets and fog Source suppression effect.Vertical ventilation + downstream of the top of the best exhaust effect,combined with the advantages of the previous two smoke conditions,while the tunnel space temperature and smoke concentration to achieve effective control. |
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