FIRE-INDUCED AIR FLOW IN BUILDINGS

Abstract

The purpose of this work is to numerically simulate the 2-D air flow induced by fire in rooms and atria with field modeling incorporating a ?-? turbulence model. The thesis is divided into five chapters. Chapter 1 describes the importance of the research on the heated air and smoke flow induced by fire and reviews three main research methods, experimentation, zone modelling and field modelling. Chapter 2 introduces the assumptions and mathematical model for the problem. Chapter 3 elaborates on the details of the initial conditions, boundary conditions, algorithm and the solution method for the problem. Chapter 4 is devoted to an analysis of the results obtained through the computer simulation. Chapter 5 presents the conclusions to the present work and recommendations for further exploration. This work simulates seven different cases of the air flow in a room or atrium fire. The fire strength varies from 50 kW to 270 kW, which can cause the hot layer temperature to rise to around 400 K to 800 K from the ambient temperature 300 K. This computer simulation uses the ?-? turbulence model and directly solves six partial differential equations, continuity equation, u-momentum equation, v-momentum equation, energy equation, turbulence kinetic energy equation and dissipation rate equation. The computer program was written in Fortran 77 and used the well known SIMPLE algorithm. The Dou Guo Ren wall function was adopted in the computation for the ? and ? boundary conditions and it proved to be very effective. Some of the parameters, such as the fire strength, fire location and door openings, were changed to study their effects on the air flow. The computer simulation was performed on the SUN and DEC workstations. The results of all seven cases are very encouraging. The predictions from the simulation were compared with the available experimental data, with reasonable agreement.