| With the rapid development of highway tunnel technology in China,the shape of the tunnel is various,and the curved tunnel gradually appears in people's field of vision.Factors such as the slope and curvature of the tunnel can interfere with the diffusion movement of the fire smoke,causing fire accidents and endangering personal safety.Therefore,FLUENT software is used to carry out three-dimensional transient numerical simulation of highway tunnel fire with longitudinal wind.The temperature and concentration distribution clouds of the longitudinal and transverse sections of the tunnel are analyzed,and the trends of temperature and concentration along the vault and the human high are discussed in detail to provide reference for personnel evacuation and protection for lining structure during the fire in the tunnel.The main research contents and conclusions are as follows:(1)When the ventilation wind speed is 2m/s,the linear tunnel fire under different slopes is studied.The variation of smoke spread,smoke temperature and CO concentration in the tunnel are analyzed.As the slope increases,the upstream backflow length is shorter and the downstream spread distance is longer.The smoke concentration in the cross section is basically symmetrical on both sides and presents a distribution pattern of upper and lower.In the downstream area of the fire source,both smoke temperature and the CO concentration increase.However,due to the relatively high wind speed,this law is not obvious.(2)Considering the influence of longitudinal wind speed,the non-slope curved tunnel fire under different curvatures is studied.It is concluded that when the ventilation wind speed is greater than 3m/s,the amount of smoke in the downstream of the tunnel is significantly higher than that in the upstream.The lateral concentration in downstream of the fire source no longer exhibits a symmetric distribution,and the concentration in the upper right corner of the cross section is slightly larger than the lower left corner.The temperature of the vault smoke in the curved tunnel is higher than that of the linear tunnel,and the temperature decreases with the increase of the curvature.This law is opposite to the ventilation wind speed of 2m/s.(3)Study on the non-slope curved tunnel fire under different fire source powers.It is concluded that in the same ventilation wind speed,the plume flow under the 5MW fire source power has a larger inclination angle to the downstream than the 20 MW firesource power,and the smoke does not settle to the bottom of the tunnel.As the power of the fire source increases,the smoke in the tunnel spreads faster,the thickness of the smoke settles increases,and the temperature of the downstream smoke is higher.(4)Change the ventilation wind speed and analyze the smoke flow of the straight tunnel and the curved tunnel fire.When changing the ventilation wind speed,analyze the smoke flow of the straight tunnel and the curved tunnel fire.When the tunnel conditions are consistent and the wind speed becomes larger,the amount of smoke in the upstream of the fire source is gradually reduced,and the downstream smoke starts to settle at a farther position,the temperature and CO concentration of the smoke are lower.(5)For the curved tunnel,when the fire source power is 5MW,the CO concentration in the human high region is the smallest in the wind speed 1m/s.When the fire source power is 20 MW,the CO concentration is obviously increased,and the wind speed needs to be increased to promote the flow of smoke in the tunnel.But as the wind speed increases,the gradient of the temperature drop decreases,and the effect of lowering the temperature by increasing the wind speed is worse.Therefore,proper ventilation wind speed is critical for fire rescue. |
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