剧场建筑性能化排烟设计探讨

分析了常规排烟设计方法在剧场建筑排烟设计申存在的问题,重点讨论了性能化排烟设计方法在剧场建筑排烟设计申排烟量计算、烟层高度设计、排烟口位置选择等方面的设计方法。     

基于性能化的电影院观众厅排烟设计

分析了常规排烟设计方法在影院观众厅排烟设计中存在的问题,重点讨论了性能化排烟设计方法在影院观众厅的排烟设计,包括排烟量计算、烟层高度设计、以及人员疏散安全验证等方面。     

商场及购物中心的排烟设计

本文针对装有自动喷洒灭火系统的商场和购物中心，在规定了“设计火灾规模”（即疏散时间内火灾范围为周长１２ｍ，放热速率为５ＭＷ）的条件下，提出了蓄烟拱的规模、烟流量、烟层温度、挡烟垂壁尺寸、排烟口数量和面积等计算公式、数据和实验曲线，讨论了排烟系统的基本功能、挡烟垂壁的设置、自动洒水对烟气的冷却作用、进气口的风速、自然排烟和强制排烟等具体问题。     

建筑火灾烟层稳态简化模型排烟效果计算

阐述建筑火灾时期烟气的危害及防排烟的必要性,并应用烟层稳态简化模型对建筑物侧墙开口的排烟效果进行计算。研究表明,烟气的产生量与其沉降速率有关,烟层沉降与否及沉降速率将威胁到室内人员的生命安全。研究可为人员的安全疏散以及房屋的自然排烟设计提供科学依据。     

某高大空间热烟试验研究

对大空间的防排烟设计主要参考"中庭"的要求进行设计,消防验收中对其防排烟系统的有效性只能依据是否符合规范来评定.许多大空间建筑超出了规范涵盖的建筑形式,参考规范中"中庭"的要求进行防排烟的设计和评价已不再适宜.在澳大利亚热烟试验标准的基础上对某大空间的烟控系统进行测试,通过对烟气层高度和烟气层温升变化等数据的分析,研究大空间烟控系统的排烟效果.结果表明:热烟试验能够模拟火灾烟气的流动,可用于评价大空间排烟系统的有效性及消防验收.     

关于高层建筑防排烟设计问题的探讨

本文论述了高层民用建筑防排烟设计方面的几个问题，从设计工作的初中中对高层建筑中庭大堂的防排烟设计、工程设计中常用的防排烟方式和排烟口的大小、布置及防烟分区与挡烟板的设置等问题提出了详尽的论述和解决办法，对高层建筑防排烟设计有一定的参考价值。     

机械排烟系统清晰高度的影响因素分析

通过对排烟口最大允许排烟量计算过程的分析,讨论了烟气温度对清晰高度的影响,推导出当排烟场所一定时,烟气层平均温度与环境温度的差与设计清晰高度之间的关系。列举典型案例,测算了不同热释放速率场所在机械排烟时控制烟气层温度不超过280℃所需的设计清晰高度限值。     

防排烟系统对拱形地铁站厅烟气蔓延的影响

地铁站厅防排烟系统对人员安全疏散具有致关重要的作用。通过烟气层沉降理论分析,编写了适用于拱形地铁站厅火灾烟气蔓延区域模型程序,研究不同机械排烟量下烟气沉降高度随时间的变化规律。研究表明,随着排烟量的增加,烟气层沉降速度变慢,排烟量为28.4 m³/s时,360 s左右烟气层方才达到溢出口高度,该设计排烟量能满足人员安全疏散要求。通过火灾动力学软件FDS数值模拟的方法,研究不同排烟量和挡烟垂壁高度对地铁站厅能见度、CO浓度的影响。研究表明,烟气从高大站厅空间向狭小的通道空间溢出,容易在通道出口处形成烟气堆积,导致通道出口处能见度最低,CO浓度最高;验证了烟气层沉降理论计算地铁站厅烟气排烟量可以满足人员安全疏散的要求;设置挡烟垂壁可以提高地铁站厅的能见度和降低其CO浓度。     

基于挡烟垂壁和通风的地铁站烟气控制

利用PyroSim软件对地铁车站站台火灾进行全尺寸数值模拟。分析采用不同的防排烟措施时,车站内的烟气扩散情况,对比分析火源附近的温度场以及车站轴面处温度场。结果表明:挡烟垂壁具有一定的防烟效果,但在火灾后期防烟失效;在设置挡烟垂壁的同时,采用地下一层送风、地下二层排烟的防排烟措施效果更佳,且着火层排烟量对烟气控制效果影响最明显。     

喷淋的冷却作用对自然排烟影响的实验研究

通过实验.研究了火源功率一定的情况下,喷淋的冷却作用对自然排烟造成的影响.针对喷淋前后烟气层温度和自然排烟速度进行了分析,结果表明,喷淋的冷却作用会对烟气层温度、自然排烟速度产生较大的影响,对建筑工程进行自然排烟设计时要充分考虑喷淋对排烟的影响.     

大空间火灾机械排烟的数值模拟分析

火灾烟气中含有多种有毒和有害成分，具有很大危害性，减少烟气危害的关键是将烟气层底面高度控制在对人员没有危害的高度。通过对大空间机械排烟的烟气流动过程进行CFD数值模拟，得出了大空间机械排烟的烟气流动性状，根据模拟结果可知，按现行设计规范，在火源释热率较大的情况下，难以将烟气层控制在理想的高度。文章建议根据火源释热率、火灾发生后的逃生时间、烟气层的控制高度合理确定大空间的机械排烟速率。     

狭长通道顶部障碍物下游火灾烟气密度跃变的数值模拟研究

火灾烟气的密度跃变过程会卷吸烟气下部的空气,使得烟气层明显增厚、质量流量显著增大,这会加大疏散与救援的难度,并影响既有防排烟设计的有效性。为明确烟气层密度跃变的机理及危害,采用数值模拟方法,研究了狭长通道火灾烟气沿顶棚水平蔓延过程中,顶部障碍物的存在对其下游烟气层密度跃变的影响。结果表明,若没有顶部障碍物的作用,仅增大热释放速率并不能使得烟气层发生密度跃变。而顶部障碍物可能引起其下游烟气流动状态突变,并引发密度跃变。跃变所产生的烟气层厚度、卷吸质量流量变化均与障碍物高度相关。并提出采用梯度弗劳德数作为判断烟气层密度跃变发生与否及衡量密度跃变效果的无量纲数。     

关于中庭建筑防排烟系统设计中排烟量的探讨

中庭建筑发生火灾的情况下,排烟系统设计的目标是应确保烟气层在认可的安全高度之上以利于室内人员的逃生或是使烟气层下降到危险高度所需的时间大于建筑物内人员安全撤离所需要的时间,因此排烟量的确定是排烟系统设计的关键.本文对中庭建筑火灾中2种火源工况下产烟量的计算公式进行了介绍,并与我国高规中确定排烟量的方法进行了对比.研究结果表明,对于轴对称羽流,NFPA模型能给出较好的预测结果;对于阳台喷射羽流,还存在一定的争论,对该情况下的羽流卷吸机理还需进行更深层次的研究;由换气次数确定的排烟量,尽管方便使用,但还存在许多不足,不能满足性能化分析的要求.本文的研究结果为我国相关规范的制订和性能化设计提供一定的依据.     

侧部重点排烟与水喷淋协同作用下隧道烟气运动研究

合理的水喷淋设计参数及排烟策略，可保证隧道有效排烟和烟气层的稳定性，为人员安全疏散提供有利环境。为研究侧部排烟模式下烟气失稳临界状态时最佳喷水流量和排烟口设计参数，采用FDS 对15 MW 火灾规模下，不同喷水流量、排烟量、排烟口间距及排烟口高度下19 组工况进行模拟计算。结果表明：喷淋流量越大，烟气层高度越高，隧道整体温度降低，改变喷水流量对控制烟气层的稳定性效益不大，隧道空间内有烟气滞留；排烟量为70 m3/s、排烟口间距为50 m、排烟口高度为3.2 m 或4.0 m 为烟气层稳定临界状态时的排烟口最佳参数，此时侧部抽吸力向上的分力与烟气的热浮力大于水喷淋拽曳力，烟气层较稳定，隧道空间内无旋涡烟气滞留，有利于排烟和人员疏散。     

Analyses of smoke management models in TFT-LCD cleanroom

This study evaluated the effectiveness and performance of smoke management models in a TFT-LCD cleanroom. Several smoke management models are discussed in a distinct 3-level cleanroom compartment. The tools used included a fire dynamics simulator (FDS) and SIMULEX. The design fires were 3 MW and 5.4 MW in ultra fast fire, respectively. In life safety, both a downward smoke exhaust system and upward smoke exhaust system, incorporating a decrease of filter fan unit air supply rate, could be used in a cleanroom, according to the simulation results of performance-based design. For occupant evacuation, the SIMULEX results showed a total evacuation time less than smoke layer descending time, which descended to 1.8 m height from floor to smoke layer in all FDS simulations. In view of property protection, insurance companies generally require significantly higher standards of property protection. For 3 MW or more heat release rate, smoke was hardly controlled by any smoke exhaust system in the cleanroom without sprinklers.     

中庭机械排烟量计算方法探析

阐述了中庭防排烟系统机械排烟量的性能化计算方法,即以区域模型为理论基础,结合中庭建筑特征设定火灾热释放率后进行火灾烟气层高度和排烟速率等计算,并给出了计算实例。     

Should Smoke Yield be Regulated for Wall, Ceiling and Floor Linings?

A major issue in fire safety engineering is the control and regulation of smoke production from wall linings. When a material burns it produces smoke. Smoke production has two attributes, its volume and its concentration. The smoke volume is the total amount of smoke per unit time, and is proportional to the heat release rate. The smoke concentration depends on the smoke yield of the material, which is defined as grams of smoke produced per gram of material burnt. Current two-zone models, generally accepted in fire safety design, determine whether tenability conditions are met based on smoke volume. In these models a distinct interface between the smoke and the clear layer is assumed. This paper focuses on the impact of smoke yield on tenability. Two issues are discussed (a) the variation of smoke yield with ventilation conditions and (b) the influence of smoke density gradients between the smoke and clear layer on tenability conditions. Two examples are presented to illustrate the significance of these issues.     

Smoke management for covered malls and atria

This paper provides an overview of the principal design considerations of smoke management systems for covered malls and atria included in a recently proposed technical guide. The engineering basis for formulating an appropriate design for a smoke management system is presented in the form of algebraic equations and graphs. Techniques to assess the level of life hazard created by a fire in an atrium or covered mall with a smoke management system are discussed. The level of life hazard is expressed in terms of the following hazard parameters: smoke layer depth; visibility through the smoke layer; and the carbon monoxide concentration and temperature rise in the smoke layer.     

Experimental study of natural roof ventilation in full-scale enclosure fire tests in a small compartment

An analysis of full-scale fire test experimental data is presented for a small compartment (3×3.6×2.3 m). A square steady fire source is placed in the center of the compartment. There is an open door and a horizontal opening in the roof, so that natural ventilation is established for the well-ventilated fire. A parameter study is performed, covering a range of total fire heat release rates (330, 440 and 550 kW), fire source areas (0.3×0.3 m and 0.6×0.6 m) and roof ventilation opening areas (1.45×1 m, 0.75×1 m and 0.5×1 m). The impact of the different parameters is examined on the smoke layer depth and the temperature variations in vertical direction in the compartment. Both mean temperatures and temperature fluctuations are reported. The total fire heat release rate value has the strongest influence on the hot smoke layer average temperature rise, while the influence of the fire source area and the roof opening is smaller. The hot smoke layer depth, determined from the measured temperature profiles, is primarily influenced by the fire source area, while the total fire heat release rate and the roof opening only have a small impact. Correlations are given for the hot smoke layer average temperature rise, the buoyancy reference velocity and the total smoke mass flow rate out of the compartment, as a function of the different parameters mentioned. Based on the experimental findings, it is discussed that different manual calculation methods, widely used for natural ventilation design of compartments in the case of fire, under-predict the hot layer thickness and total smoke mass flow rate, while the hot layer average temperature is over-estimated.