Numerical Simulation Study Of Highway Tunnel Fire

Fire in the highway tunnel will cause enormous losses. The control of smoke in the tunnel fire will take great place in the fire protection and prevent. Numerical simulation of smoke flow and tunnel fire is discussed in this paper. Provides the fast accurate policy-making method for tunnel fire preventing and controlling.First, the paper introduces the highway tunnel fire about its characteristies, causes, damages. The status and future of the technology of fire simulation in quo of research in the world is introduced. Then, with the combination of theoretic analysis and fire experiment, the paper analyzes the layout and process of combustion in the fire. Based on the research results that calculation of heat release rates and products of flame and the rule that the temperature of fire changed with the time, the way of simulation in the turbulence combustion is presented. The model of PDF (Probability density function) in turbulent combustion is studied. Analyses the characteristic of smoke flow in tunnel fire and summarizes the law of three-dimensional flow. Based on these, the law of buoyant plume flow is analyzed. The influence and affection of critical velocity to the smoke's flow is discussed. The paper explained the principles of three-dimensional field simulation technology of tunnel fire. Field simulation of tunnel fire and technology of CFD (Computational Fluid Dynamics) simulation is introduced and compared. Based the principles of field model, the fundamental model, turbulent model and boundary condition of smoke flow progress in tunnel fire is established. The separate method and solve method of basic equation groups are built. The basic function and structure of commercial soft Fluent is recommended. The principles of numerical compute is submitted. The tunnel fire experimental bench has been built and the experiment has been made. With the help of Fluent, numerical computation has been taken to highway tunnel fire in different air velocities, the temperature and the distribution of concentration of the smoke has been simulated.By means of analyzing, the paper offers the law of smoke flow in the tunnel fire. Ventilation control was took with the critical ventilation velocity 2m/s to a tunnel fire by the 20MW heat release rate, the results is similar with the experiment. Compared the results the paper fund that the velocity of ventilation is very important to the distribution of the temperature. With the aggrandizement of ventilate velocity, the temperature and concentration of the smoke in the up area is decreased. The ventilation with the velocity of 2m/s can prevent the smoke's roll back, thereby, it can reduce casualties and cut down the loss. The field model of tunnel fire is suitable for simulate tunnel fire and the mathematics model is applicability. The results of numerical calculation is conform to experiment generally, it is prove out that use the simulation software in the research of tunnel fire smoke flow is the efficient way, it can give the quick and nice decision to prevent and cure the tunnel fire.