Numerical Simulation Of Small-radius Curves Tunnel Fire Ventilation

In this paper, large eddy simulation technology is applied to study the numerical simulation of fire smoke flow law in small radius curve tunnel in the highway of Ya'an to Xichang in Sichuan. The main works and progresses attained are as follows:(1) Based on the analysis of ventilation theory of highway tunnel fire and combined the special boundary condition of small radius curve tunnel, appropriate control equation in numerical calculation and numerical simulation software are determined, and three-dimensional numerical model of curve tunnel fire smoke flow is established. Then setting method of fire source and simulation working condition are determined on the basis of codes for tunnel fire protection and tunnel fire incidents at home and abroad.(2) Backflow control method of fire smoke is studied and the critical wind velocity of Ganhaizi curve tunnel in the fire emergency situation is proposed from a thorough analysis on simulation results. The characters of fire smoke flow in curve tunnels, which include velocity, temperature and concentration distributions, are analyzed under different ventilation conditions.(3) Though the transverse and longitudinal comparison analysis in different tunnel curvature, the effect of tunnel curvature on fire smoke flow is studied quantitatively and the special motion laws of fire smoke flow are summarized.(4) The distribution of temperature field of different fire working condition in small radius curve tunnel is studied; and aiming at this curve tunnel's fire safety design, the fire-resistant grade of the building material for the upper part of tunnel should be enhanced in the construction design and the ventilation equipments on the crown should be defended form fire and high temperature.(5) High temperature damage and toxicity hazard of fire smoke are studied and the control methods of smoke are investigated in small radius curve tunnel.The fire smoke flow model of this paper can offer comprehensive information; hence it can be served as a reference for the further research on curve tunnel fire and ventilation in China.The research results in this paper can provide not only direct guidance for the formulation of the scheme concerning the Ganhaizi Curve Tunnel's disaster prevention and relief, but also relevant reference for the other curve tunnel fire safety projects.