Numerical Simulation of Fire in the Temperature Stratified Atrium with a Mathematical Field Model

[摘要] References(6)2-dimensional numerical computations of the fire induced convective heat flow in an atrium have been done using a pseudo K-ε flow model of a viscous heat conducting compressible fluid. The size of the atrium is 30 m high and 30 m wide, with a 3 m high doorway at the bottom of the wall.The effect of pre-fire temperature stratification which can be formed by normal air-conditioning has been considered. Prior to the simulated fire initiation, the stratified environment is calculated numerically with the pseudo- K-εfield model. The initial conditions of the pre-fire computation are set as that the air in the atrium is initially motionless with uniform temperature of 20°C. The solid boundary has been divided into two parts. The temperature of the ceiling and the walls of the upper part has been set as 40°C, and the temperature of the floor and the lower wall has been set as 20°C.After a steady state is attained in the pre-fire calculation, a fire-simulating heat source is placed at the center of the floor. The initial temperature is set as 20°C and then its temperature is increased linearly unit 800°C in 5 minutes and then kept constant.As a results of the computation, it has been found that the ceiling-mounted heat detectors or smoke detectors may not respond to the early stage of the fire occurred in a temperature stratified high atrium. The pre-existing hot temperature layer may so inhibit penetration of the smoke flow that the initial smoke layer is formed not adjacent to the ceiling but under this hot layer. Thus ceiling-mounted smoke detectors or heat detectors may not provide early stage fire detection in high atria with air-conditioning.

[学科分类] 环境科学（综合）