Fire alarm system relates the safety of people's life and property when the fire occurs in high-rise buildings. The characteristic of the smoke spread process in the fire is a crucial problem for design of the fire alarm system. In this paper, the smoke spread process under different ceiling heights is investigated via the computational fluid dynamics method and the numerical simulation in high-rise buildings. The temperature, visibility and obscuration rate in the fire are discussed and the technology about the fire alarm system is studied. From the simulation results, some conclusions are obtained as follow. When the height of ceiling with the smoke detectors is above 16.0 m, the higher ceiling, the lower temperature, and the detected maximum temperature is below 35.0 °C. The alarm time of the smoke detector lags that of the cloud chart of visibility, since it takes time for the smoke to propagate in the dark room inside the detector. When the ceiling height is below 8.0 m, the horizontal installation way of the line type smoke detector (LSD) is better than the vertical way. Simulation results show that the numerical simulation method is reliable and used widely in the fire information research.

高层建筑发生火灾时，火灾报警系统关系到人们生命财产安全。火灾中烟雾扩散过程的特性是火灾报警系统设计的关键问题。本文通过计算流体动力学方法和高层建筑的数值模拟研究了不同天花板高度下的烟气扩散过程。讨论了火灾中的温度，能见度和遮挡率，并研究了火灾报警系统的技术。从仿真结果可以得出以下结论。当烟雾探测器的天花板高度超过16.0 m时，天花板越高，温度越低，检测到的最高温度低于35.0°C。烟雾探测器的警报时间落后于可见性云图的警报时间，因为烟雾在探测器内部的暗室中传播需要时间。当天花板高度低于8.0 m时，线型烟雾探测器（LSD）的水平安装方式要好于垂直安装方式。仿真结果表明，该数值模拟方法可靠，在火灾信息研究中得到了广泛的应用。