摘 要

本文主要对公路隧道火灾中为了提高安全性和减少烟流。本文提出了一个小规模的隧道模型，研究火灾烟气控制的纵向和横向通风系统的数值研究。我们研究了通风系统的温度分布和分层的影响，估计通风系统的有效性。流的特点是温度场，温度分布和弗劳德数。采用FDS数值模型与实验结果将被用来评估临界速度.

关键词: 隧道火灾，烟气流动，FDS，临界速度

Abstract

This paper focuses on fires in road tunnels in order to increase safety and reduce smoke flow. This paper proposed numerical investigations carried out on a small scale tunnel model to study the fire-induced smoke control by longitudinal and transverse ventilation systems. We studied the effect of two ventilation systems on the temperature distribution and stratification of the smoke to estimate the effectiveness of ventilation systems. The flow is characterized by the temperature fields, temperature profiles and the Froude number. With the use of FDS the numerical model and experiment result will be used to evaluate the critical velocity .

Key Words：Tunnel fire, Smoke flow, FDS, Critical velocity.

CONTENTS

Chapter 1 Introduction 2

1.1 Tunnel Fire disasters 3

1.2 Research status 5

1.3 Research contents and methods 3

1.3.1 Research contents.............................................................................................9

1.3.2 Research methods............................................................................................9

Chapter 2 Tunnel fire simulation measurement standard and CFD numerical simulation 10

2.1 Introduction 10

2.2 Froude number 10

2.3 CFD numerical simulation 14

2.4 Large Eddy Simulation..........................................................................................16

Chapter 3 Research and development status abroad 17

3.1Tunnel Fire Experimental research..........................................................................17

3.2 Critical velocity.......................................................................................................17

Chapter 4 within the country - Theoretical consideration..........................................................20

4.1 experimental data ...................................................................................................20

4.2 Scaling parameters..................................................................................................21

4.3 Temperature field in tunnel fire..............................................................................22

4.4 description of tunnel fire........................................................................................24

Chapter 5 effects of longitudinal ventilation on Tunnel fire......................................................27

Conclusion..................................................................................................................................29

Reference....................................................................................................................................30

Acknowledgment........................................................................................................................32

CHAPTER 1 INTRODUCTION

Tunnel fire is a major cause of accidents in mining industry which threatens lives of many people among the field. But fire does not go alone without smoke control in which are all affected by tunnel geometry, ventilation system also chemical reaction.

The exposure to fire in not only the threat to life but also smoke inhalation which can cause difficulties in breathing and reduce visibility in tunnel during evacuation. Longitudinal ventilation system is diversely used in many fields thus preventing back-layering of smoke in a tunnel. Back-layering is the situation when ventilation system is low and the smoke produced from the fire can travel in the upstream direction against the direction of the ventilation

The smoke from fire reduce visibility and cause slower evacuation, toxic gases in the smoke can also be fatal in duration of time. So in all conditions possible the ventilation system must ensure safe environment.Most of the major accidents in recent years have been in private as opposed to state mines. At least 104 people died in 2009 in an accident in Heilongjiang; an explosion killed 45 people at the Xiaojiawan coal mine in Sichuan province and a few days later 14 miners were killed in Jiangxi province. 

Experiments and research have carried out to overcome smoke flow in a tunnel. Thomas and Heselden results are largely used in design which suggest the critical ventilation velocity depends on the cube root of the heat release per unit width of the tunnel.

1.1 Tunnel fire disasters

mining tunnel fire disasters or accidents are the most dangers in mining industry today. Thousands of miners die each year due to different causes. Generally speaking surface mining has less accidents to underground mining.

Causes of mining fire accidents varies from Methane and Consecutive Coal Dust Explosions in coal mines (Methane which is a highly explosive gas trapped within coal layers can be triggered due to Mechanical errors from badly used or malfunctioning mining equipment), Blasting Related Accidents (fly rock, premature blast, misfire and mine-Induced Seismicity) other causes of fire accidents are electrical and exploding vessels under pressure.

China has the world high records of mining accidents and many of them occur in coal mines. According to a 2003 government report, the coal miners' death rate per one million population was about 37 times that of America's coal-mining death rate. Below are relevant tables and statistics of accidents during 2001-2008: