中文摘要：

为研究层化环境对内部火灾烟气扩散的影响,以线羽流为研究对象,在正常环境下线羽流流动特性研究的基础上,通过理论分析对恒温度梯度环境中线羽流的流动特性进行了分析研究,得到线羽流的扩散半径、轴心速度、轴心密度差随高度的变化规律,线羽流所能达到的最大高度,烟气浮力发生变化的临界高度等.

英文摘要：

Thermal-stratified environment is often seen in atria or other large space buildings with glass roofs due to the solar radiation. In order to study the effect of the thermal-stratified environment on the smoke spread in fire cases,theoretical analysis of the thermal dynamics of the line plume in the environment with constant vertical temperature gradient was carried out based on the former research in this paper. Variations of the radius,central velocity,density difference of the line plume with height were derived,and the maximum height of the plume was obtained. The upward buoyancy due to the line source changed its direction at the height of 76% of the maximum height which the plume could rise.