可燃性PVC电缆燃烧时的火蔓延速度

电缆燃烧时火蔓延速度受到多种因素影响,与电缆本身粗细、电缆布置方式和环境通风条件有关。不同型号的PVC电缆,火蔓延速度不同,细电缆较粗电缆火蔓延速度要快;电缆的布置方式对火蔓延速度产生影响,无风环境中PVC电缆水平布置时火蔓延速度约为0.05 m.min-1,垂直布置时火蔓延速度约为0.2~0.3 m.min-1;风速和风向对电缆燃烧的火蔓延速度也有影响,当风与火蔓延同向时,在一定范围内增加风速会对电缆火蔓延速度起加速作用,超过此范围后(1.5~2.0 m.s-1),增加风速火蔓延速度下降;反向增加风速,火蔓延速度降低。     

含添加剂细水雾熄灭油池火的机理及实验

为了提高普通细水雾灭火的有效性，采用小尺度实验方法，通过在普通细水雾中加入添加剂，研究了在受限空间内含添加剂细水雾扑灭油池火的有效性．实验研究发现：当火源位于细水雾的作用范围内时，灭火时间较短，灭火性能较高；当火源位于细水雾的防护区域外时，灭火有效性显著降低．而在相同流量和压力下向细水雾中加入添加剂，能显著地影响它的灭火性能，使火焰容易熄灭，灭火时间大大缩短，从而提高了细水雾的灭火能力，因此细水雾对受限空间内油池火的灭火有效性大大增强．通过细水雾对O2、CO、CO2的体积分数以及对火焰温度、烟气温度影响分析，为筛选和制备细水雾灭火添加剂提供了实验数据．     

含添加剂细水雾熄灭油池火的机理及实验

为了提高普通细水雾灭火的有效性,采用小尺度实验方法,通过在普通细水雾中加入添加剂,研究了在受限空间内含添加剂细水雾扑灭油池火的有效性.实验研究发现:当火源位于细水雾的作用范围内时,灭火时间较短,灭火性能较高;当火源位于细水雾的防护区域外时,灭火有效性显著降低.而在相同流量和压力下向细水雾中加入添加剂,能显著地影响它的灭火性能,使火焰容易熄灭,灭火时间大大缩短,从而提高了细水雾的灭火能力,因此细水雾对受限空间内油池火的灭火有效性大大增强.通过细水雾对O2、CO、CO2的体积分数以及对火焰温度、烟气温度影响分析,为筛选和制备细水雾灭火添加剂提供了实验数据.     

油池火下横隔梁对多肋钢筋混凝土T梁桥温度场的影响

基于油池火焰蔓延特性,探究了火灾下横隔梁对多肋钢筋混凝土T梁桥温度场的影响。理论分析了T梁底火焰蔓延总长度与热释放速率间的无量纲关系,用FDS建立4种火灾场景的流体计算模型,分析T梁边界温度时空分布规律,将FDS计算结果加载到T梁桥有限元模型上,计算截面内部温度场。结果表明：在开放空间,T梁底火蔓延与无量纲热功率之间的线性比值大于封闭空间的2.58;横隔梁有效降低了火焰邻近区域的温度,在顺桥向将T梁边界温度场分成4个区域,各分区间温度比无横隔梁时分别降低9.7%、41%、56.8%。说明横隔梁限制了热传递,使火源直接作用的梁构件温度梯度梁肋中部提高33%,梁底提高13.3%,翼板底提高5%。     

碳源对自蔓延高温合成TiC粉末的影响

在氩气保护下用钛、碳元素通过自蔓延高温合成(SHS)工艺制备了碳化钛,采用X射线衍射(XRD)和扫描电子显微(SEM)技术,分析检测了采用不同碳源合成的碳化钛的物相组成和微观结构.结果表明,钛与碳元素粉末的自蔓延合成产物均为碳化钛相,产物形貌因碳源的不同而有所不同,以石墨为碳源所合成的TiC晶型比较完整,粒度相对粗大、颗粒均匀性相对较好,团聚较少,更接近化学计量比.     

基于(火用)分析法抽汽压损对机组经济性的影响

抽汽压损是一种不明显的热力损失,使蒸汽的作功能力下降、热经济性降低.首先定性分析抽汽压损对机组经济性的影响,根据(火用)的物理意义定义锅炉(火用)效率、机组(火用)效率、发电(火用)耗率的数学表达式；由小扰动理论和微分理论,建立抽汽压损变化对抽汽量影响的微分关系式,以及锅炉(火用)效率、机组(火用)效率、发电(火用)耗...     

科学技术对建筑空间的影响与推动

从本质上说,建筑是一种空间的营造过程,是在技术基础上进行的建造活动.空间的功能、结构、形态在其发展过程中受到科学技术不同程度的影响.通过对影响建筑空间发展因素的分析,探讨了科学技术对建筑空间演变的影响与推动作用.     

Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

Experimental study and numerical simulation of spread law for fire on tunnel

In order to research spread law and distribution law of temperature nearby fire sources on roadway in mine, according to combustion theory and other basic, the theory model of temperature attenuation was determined under unsteady heat-exchange between wind and roadway wall. The full-size roadway fire simulation experiments were carried out in Chongqing Research Institute of China Coal Technology & Engineering Group Corporation. The development processes of mine fire and flow pattern of high temperature gas were analyzed. Experimental roadway is seen as physical model, and through using CFD software, the processes of mine fire have been simulated on computer. The results show that, after fire occurs, if the wind speed is less than the minimum speed which can prevent smoke from rolling back, then the smaller wind speed can cause smoke to roll back easily. Hot plume will lead to secondary disasters in upwind side. Because of roadway wall, hot plume released from roadway fire zone has caused the occurrence of the ceiling jet, and the hot plume has been forced down. Whereas, owing to the higher temperature, buoyancy effect is more obvious. Therefore, smoke rises gradually along the roadway in the flow process, and the hierarchical interface appears wavy.Oxygen-enriched combustion and fuel-enriched combustion are the two kinds of combustion states of fire. The oxygen content of downwind side of fire is maintained at around 15% for oxygen-enriched combustion, and the oxygen content of downwind side of fire is maintained at around 2% for fuel-enriched combustion. Furthermore, fuel-enriched combustion can lead to secondary disasters easily.     

空心剪力墙结构房屋动力特性试验研究

为了研究空心钢筋混凝土剪力墙结构小高层房屋的动力特性，进行了10层房屋1：2．8比例模型的模态试验和拟动力试验，获得了结构的周期、振型、动力放大系数等参数．研究结果表明，这种空心剪力墙结构的动力特性有别于传统的剪力墙结构，性能更优于传统的剪力墙结构．     

高层建筑玻璃幕墙的抗爆炸设计

玻璃幕墙是一种融建筑艺术和建筑功能于一体的建筑外维护构件,在高层建筑中得到广泛应用。近年来,世界各地袭击高层建筑的恐怖活动频繁发生,促使建筑设计中逐渐考虑到建筑的抗爆炸设计要求。文章针对建筑玻璃幕墙的爆炸冲击波防护问题,在分析冲击波对建筑幕墙破坏原理的基础上,给出了玻璃幕墙抵抗爆炸冲击波设计的途径,建立了冲击波荷载的计算准则。最后,提出了玻璃幕墙的冲击波试验方案,并具体介绍了距离试验的实施方法。     

高层建筑玻璃幕墙的抗爆炸设计

玻璃幕墙是一种融建筑艺术和建筑功能于一体的建筑外维护构件,在高层建筑中得到广泛应用。近年来,世界各地袭击高层建筑的恐怖活动频繁发生,促使建筑设计中逐渐考虑到建筑的抗爆炸设计要求。文章针对建筑玻璃幕墙的爆炸冲击波防护问题,在分析冲击波对建筑幕墙破坏原理的基础上,给出了玻璃幕墙抵抗爆炸冲击波设计的途径,建立了冲击波荷载的计算准则。最后,提出了玻璃幕墙的冲击波试验方案,并具体介绍了距离试验的实施方法。     

Experimental study on fire smoke movement in a multi-floor and multi-room building

With the rapid development of social economy in China, more and more high-rise buildings were set up. How to avoid and reduce fire loss of high-rise buildings has be-come not only the key problems of fire departments, building designers and administra-tions, but also the new challenges of fire safety researchers[1]. Because of fire-heating air pressure in high-rise building fire[2,3], high temperature smoke may spread upward or downward from the fire resource floor along all kinds of passagewa…     

塔楼群玻璃幕墙碎粒飞行轨迹预测方法

结合某塔楼群玻璃幕墙的风灾实例,进行了塔楼群玻璃幕墙碎粒飞掷物的运动轨迹预测,研究了4种不同风场条件对幕墙碎粒飞行轨迹的影响。首先,在对大涡模拟方法及参数设置的有效性验证的基础上,通过紊流边界层风场内塔楼群的非定常绕流大涡模拟,获取了建筑周围的三维非定常绕流场。然后,采用五阶龙格库塔法,求解粒状飞掷物的三维刚体运动方程,通过均匀流场下飞掷物轨迹计算方法与文献试验结果的对比,验证了本文方法的有效性。最后,对比分析了不同流场条件对颗粒的飞行轨迹及飞行速度的影响。结果表明,本文飞掷物运动轨迹计算方法结合大涡模拟获取的流场能够对飞掷物飞行轨迹进行有效预测;对同一位置释放的颗粒,与理想均匀流场相比,三维自由来流场中颗粒的飞行速度和飞行距离相对较低;三维自由来流场忽略湍流成分时,会使颗粒的飞行速度进一步降低,而飞行距离增大;对于塔楼群三维非定常绕流场,与理想均匀流和三维自由来流场的飞掷物轨迹预测的结果相差较大,且飞掷物的飞行轨迹受绕流场中不同初始位置的影响较大,并可能显著影响最终的评估结果。因此,飞掷物的飞行轨迹应充分考虑建筑群周围的三维非定常绕流场和初始破坏位置的影响。     

A case study on fractal simulation of forest fire spread

This paper relates to the semi-empirical model based on fire field energy balance and the physical model based on land temperature, aiming to provide a practical way of describing fire spread. Fire spread is determined by the characteristics of combustible materials and the agency of meteorological factors and terrains. Combustible materials, such as surface area, have no featured scale, yet the process of forest fire spread contains the self-replicating feature, both of which contribute to the self-similarity of fire spread. Consequently, fire behavior can be described by fractal geometry. In this research, we select Wuchagou forest in Da Hinggan Mountains as the experimental site where a forest fire took place three years ago. The forest fire was detected on low-resolution NOAA-AVHRR images, and fire spread was simulated on high-resolution TM images as another attempt to merge information. Based on remote sensing and GIS, we adopted the method of limited spreading lumping (DLA) to describe growing phenomenon to simulate the dynamic process of fire spread and adjusting shape of the result of fire simulation by the scale rule. As a result, the simulated fire and the actual fire manifest the self-similarity in their spreading shapes as well as the quantitative similarity in their areas.     

A case study on fractal simulation of forest fire spread

This paper relates to the semi-empirical model based on fire field energy balance and the physical model based on land temperature, aiming to provide a practical way of describing fire spread. Fire spread is determined by the characteristics of combustible materials and the agency of meteorological factors and terrains. Combustible materials, such as surface area, have no featured scale, yet the process of forest fire spread contains the self-replicating feature, both of which contribute to the self-similarity of fire spread. Consequently, fire behavior can be described by fractal geometry. In this research, we select Wuchagou forest in Da Hinggan Mountains as the experimental site where a forest fire took place three years ago. The forest fire was detected on low-resolution NOAA-AVHRR images, and fire spread was simulated on high-resolution TM images as another attempt to merge information. Based on remote sensing and GIS, we adopted the method of limited spreading lumping (DLA) to describe growing phe     

胶合板表面火蔓延特性研究

实验研究了在一定风速作用下典型的可燃固体材料三合板和五合板上下表面都处于流场中的情况，表面火蔓延的特性，并与施加超细水雾后火焰的蔓延状态对比，探究了细水雾对固体燃料火焰的抑制作用。     

火灾后无机胶植筋拉拔试验研究

无机胶较有机胶具有良好的耐高温性能,进行火灾后无机胶植筋的拉拔试验研究对完善后锚固技术规范具有重要的理论意义。文章研究了不同钢筋直径、不同植筋深度的构件的拉拔承载力及其破坏形态,分析了各个植筋试件拉拔极限承载力及承载力损失,阐明了植筋深度、钢筋直径与拉拔承载力的关系。结果表明:火灾后试件在植筋深度为15 d和20 d时,试件发生钢筋的滑移破坏;当植筋深度为22 d时,试件为钢筋的颈缩破坏。在钢筋直径一定时,植筋深度为15 d或20 d时,其高温后的极限拉力较常温下均折减50%以上;随着植筋深度的增加,混凝土内部温度场逐渐递减,高温后的极限拉拔承载力随二者变化呈增长趋势,高温后的极限拉力呈增长趋势,且锚固长度越长极限拉力增加愈明显。