The effect of fine water mist working pressure on the temperature and smoke transportation in the utility tunnel
In order to investigate the effect of fine water mist pressure on the temperature field and smoke of the utility tunnel fires,through the construction of 1:6 scaled corridor test bed,using the flow coefficient of 3 of the fine water mist nozzle,the design of the corridor fire test under five different fine water mist working pressure,comparative analysis of the corridor fire temperature field and smoke under the five conditions of the pattern of change of temperature field and smoke.The results show that:prop-erly increasing the spray pressure can improve the fire extinguishing efficiency of the water mist,and with the increase in the pressure of the water mist,the flue gas temperature in the tunnel first greatly reduces and then slowly decreases,the flue gas flow rate slows down,and the height of the flue gas lay-er drops.When the pressure of fine water mist is 2 MPa,the flue gas temperature peaks earlier than when there is no fine water mist,and the peak value is greatly reduced;when the pressure reaches 4 MPa,the peak temperature decreases more slowly.In addition,it is found that the temperature distri-bution in the horizontal direction shows a gradual decay trend,with the highest temperature at the cen-ter of the fire source;in the vertical direction,the closer to the roof,the higher the temperature.The horizontal and vertical temperature distribution of the roof of the utility tunnel under different fine water mist pressures are well fitted with the exponential model,and the exponential model can predict the horizontal and vertical temperatures of the roof under different fine water mist pressures.Based on com-prehensive analysis,the pressure of 3 MPa,fine water mist on the fire suppression and smoke discharge efficiency are higher,set the fine water mist pressure parameters should not be too large to ensure that the smoke has less impact on the basis of the completion of the fire suppression and cooling.The results provide a reference for the optimization of the design of water mist fire extinguishing systems and the improvement of smoke evacuation efficiency in utility tunnel.
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