Numerical simulation of fire smoke spread in long highway tunnel
In order to study the influence law of jet fan wind speed,installation angle and change of exhaust hole conditions on fire smoke spread in long highway tunnels,the model of the center section(300 m)of a 10 km sepa-rated tunnel was established,and the non-premixed combustion model was adopted.The concentration,temperature and diffusion of toxic gas in the tunnel under different working conditions were analyzed.By changing the wind speed,installation angle and exhaust hole conditions of the jet fan,the fire smoke spread law,temperature distribu-tion and CO gas movement trajectory under different working conditions were studied,and the influence degree of different factors on smoke diffusion was obtained.The results showed that the exhaust effect was the best when the fan jet velocity was30.2 m/s,and the average volume concentration of smoke in the tunnel was 6.16×10-3.In a certain range,increasing the tilt angle of the fan could effectively increase the fire smoke exhaust effect in the tun-nel,but the continuous increase of the tilt angle might hinder the effect of jet air,making the fire smoke increase in the tunnel.Comprehensive comparison showed that the smoke exhaust effect was the best when the fan installation angle was 3°.The exhaust effect of different exhaust hole layout:double row 1.5 m×4 m>double row 2.45 m×2.45 m>single row6 m×1 m;the average volume concentration of smoke in the tunnel was 1.38×10-2、2.25×10-2、5.27×10-2,respectively.
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