Numerical Simulation And Model Experiment On Smoke Concentration Field In Interchangeable Ventilationhighway Tunnel Fire

With the scale of expressway construction increasingly enlarged,the number of theinterchangeable ventilation highway tunnel has increased rapidly in recent years.But once the fire breakes out in highway tunnels,serious casualties and property losswill be caused because of the large length of tunnel.And the biggest factor which influencedpeople’s escape is the poisonous smoke in the tunnel fire.So understanding and masteringthe smoke distribution and change rules in the tunnel fire makes a great significance toformulating a reasonable disaster preparedness plan and conducting effective personnelevacuating and rescue.The paper firstly analyzed the k turbulent double-equation model with buoyancymodification and the specific steps of SIMPLE arithmetic aimed at the the basic theories ofnumerical simulation of highway tunnel fire.It also studies the basic theories on model testand goes through the similarity relations of the main physical quantities related to modeland prototype according to the similarity criterion that the highway tunnel fire must besatisfied.Secondly, taking Lianhua tunnel in Xiamen as the research object,the paper conductsthree-dimentional steady and transient numerical simulations on highway tunnel fire usingFLUENT software.It studies the critical wind velocities under different firescales,longitudinal distribution rules of smoke concentration at different test point in thetunnel at different ventilation wind velocities,transverse distribution rules of smokeconcentration at different cross-section of the fire downstream,the laws of smoke flow andspreading,the variations of smoke concentration and the influence of cross aisle on smokedistribution.Thirdly,tunnel fire experiment is conducted with the test platform set up using Lianhuatunnel as the object. The critical wind velocities and the change rules of smokeconcentration is tested and the results are compared with the simulated results.It turned outthat critical wind velocities and the change rules of smoke concentration obtained innumerical simulation can be applied to actual tunnel fire studies.Finally,the harm of the poisonous gas generated in tunnel fire to human body andpeple’s psychic reaction and behavior reaction are introduced.Using the datas obtained fromthe model test,the paper calculated escape time under a fire scale of10MW.The controlrange of smoke concentration and reasonable spacing between cross aisles are given in the case that people can escape safely. The ventilation method,basic principles and workflow ofevacuation and rescue under the tunnel fire mode is also introduced.The research achivements of this paper can provide a reference to formulate theventilation scheme, evacuation and rescue plans if the fire breakes out in Lianhua tunnel.