Abstract

With the modernization of urban development, land resources are becoming increasingly scarce. A new type of building model comprising an underground depot and a superstructure has been constructed. To study the hybrid ventilation (HV) in interlayer of the underground depot with a superstructure under monorail line section fire, full-scale numerical simulation and reduced-scale (1:50) experiment were performed. Five ventilation velocities were used under a certain heat release rate. The temperature distribution and stratification in the interlayer were examined, and the movement of the fire smoke was analyzed. The smoke layer was visualized using a laser sheet and the smoke layer thickness determined by N-percentage rule (N = 10, 20, 30) was compared with the results of visual observation. At the same time, CFD simulations were conducted to measure the height of smoke layer and the smoke front propagation. Besides, the distribution of carbon monoxide (CO) in the interlayer was also simulated. The results show that N value of 30 could properly determine the smoke layer thickness in relatively stable stage of combustion. HV had a better effect on smoke control than natural ventilation (NV) did. At a ventilation velocity of 1.4 m/s, the smoke layer in the interlayer remained in a steady state until its exclusion from the building. CO could be effectively controlled and did not spread all over the interlayer in HV systems. The structure of HV system can be adjusted according to the actual conditions of the various sizes and types of buildings. Thus, the HV system shows good adaptability and can be directly applied to the design and installation of new buildings such as underground garages and depots. The results of the fire dynamic simulations and experimental tests exhibited considerable agreement.

摘要

随着城市发展的现代化，土地资源日益稀缺。一种由地下仓库和上层建筑组成的新型建筑模型已经建成。为研究单轨线段火灾下带上部结构的地下车辆段夹层混合通风（HV），进行了全尺寸数值模拟和缩小比例（1:50）试验。在一定的放热率下使用五种通风速度。对夹层内的温度分布和分层进行了检查，并分析了火烟的运动。烟雾层使用激光片可视化，烟雾层厚度由N百分比规则（N = 10, 20, 30) 与目测结果进行比较。同时，进行CFD模拟，测量烟层高度和烟锋传播。此外，还模拟了夹层中一氧化碳（CO）的分布。结果表明，N取值 30 可以较好地确定燃烧相对稳定阶段的烟气层厚度。与自然通风 (NV) 相比，HV 对烟雾控制的效果更好。在 1.4 m/s 的通风速度下，夹层中的烟雾层保持稳定状态，直到它被排除在建筑物之外。在高压系统中，CO 可以得到有效控制，并且不会扩散到整个夹层。高压系统的结构可以根据各种规模和类型的建筑物的实际情况进行调整。因此，高压系统显示出良好的适应性，可直接应用于地下车库、车厂等新建建筑的设计和安装。火灾动态模拟和实验测试的结果显示出相当一致的结果。