共查询到19条相似文献,搜索用时 156 毫秒
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细水雾与固体木垛火相互作用的实验研究 总被引:1,自引:0,他引:1
为了更好地研究细水雾熄灭固体火焰的机理及其有效性 ,建立了单流低压细水雾灭火模拟实验平台 ,在 3m× 3m× 3m的受限空间中开展了一系列的灭火实验。实验过程中采用了两种不同功率的木垛火源 ,利用热电偶和红外热像仪对细水雾施加前后的火焰的温度场进行了实时观察研究 ,结果表明当细水雾的压力低于 0 .2 MPa时 ,细水雾不能有效地扑灭木垛火 ,当细水雾的压力较低时 ,喷嘴距火焰表面的距离和细水雾施加的流量是影响细水雾灭火有效性的关键因素 ;同时 ,功率越大的木垛火 ,越易被细水雾扑灭。 相似文献
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为了进一步研究混合腔内部流场和参数最佳组合的两相流装置,设计了6 种不同结构的两相流雾化喷嘴,并实验测定雾滴粒径、雾滴轴向速度、雾化角和雾通量等相关雾化特性参数。在实验基础上,采用Fluent 模拟软件对混合腔内部的速度流场、压力流场和气液体积分数进行模拟分析,对实验结果进行补充与验证。得到雾化特性和灭火效果兼优的最优喷嘴的工作参数为:液体工作压力0.4 MPa,液体质量流量为60.0 kg/h,气体工作压力0.6 MPa,气体质量流量为0.1 kg/h,喷孔直径0.8 mm,注气孔数32 个。 相似文献
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《Planning》2015,(11)
为了研究自然循环的静态不稳定特性,通过对一个实验系统建立两相自然循环物理模型和数学模型,编程计算了两相情况下自然循环流量,研究自然循环流量漂移不稳定性的静态分岔特性及其影响因素。其中在实验段内,单相和两相段由净蒸汽产生点划分,净蒸汽产生点由萨哈-朱伯模型计算,两相摩擦压降采用均相流模型计算。最终得到了流量漂移的分岔特性曲线,并给出了相应的两相自然循环的稳定性准则,同时讨论了实验段入口欠热度、系统压力对分岔特性曲线的影响,并比较了分相流与均相流模型的计算结果。结果表明,提高入口温度、提高系统压力有利于系统稳定,分相流的计算结果比均相流稳定。 相似文献
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分析了目前消防部队配备的移动式细水雾灭火装置的灭火机理和类型特点,通过对同样工作流量的细水雾灭火装置和喷雾水枪进行的水雾粒径测量和灭火对比试验研究后,得出了相关结论。 相似文献
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This paper describes both theoretical and experimental studies on the application of a portable water mist extinguisher in suppressing multiple fire types. Two prototype portable water mist fire extinguishers were developed and their feasibility in extinguishing flammable liquid, cooking oil and wood crib fires, and for use in fires associated with an energized target was investigated. The interaction between water mist and the fire plume was studied by analyzing the instantaneous process of fire extinction, and fire and fuel temperature profiles. Both theoretical analysis and experimental results showed that the extinguishing mechanisms and process as well as water mist characteristics required (such as water flux density, droplet size and spray coverage) change with the types of fires encountered. The portable water mist extinguisher with appropriate mist characteristics was able to extinguish multiple fire types. 相似文献
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由于对民机货舱中不同气液流量的低压双流体细水雾研究较少,且对单个喷头雾通量和雾动量的定量、定性分析不够完善,还需设计开展实验进行更深入的研究。参考美国联邦航空管理局(简称“FAA”)制定的相关标准,设计并搭建飞机货舱低压双流体细水雾实验平台,主要包括FAA全尺寸飞机货舱、低压双流体细水雾系统。采用的喷头与常规的喷头有所不同,喷出的细水雾是一个圆形平面,具有优良的弥散性和滞空性。实验中采用马尔文粒径分析仪结合Spraytec软件测量不同气液流量下的细水雾雾滴粒径,发现当气体流量从250 L/min增加至350 L/min、液体流量保持0.5 L/min不变时,细水雾雾滴粒径从130 μm降低至95 μm;当液体流量分别为0.75 L/min和1.0 L/min时,粒径大小分别从161 μm降至110 μm,从201 μm降至142 μm。根据美国防火协会的标准,采用量杯收集法测量得到不同气液流量下的雾通量,发现单独增加气体流量或液体流量,其雾通量都会增加。当气体流量为350 L/min、液体流量为1.0 L/min时,雾通量达到最大值,为0.255 L/(min·m2)。利用粒子图像测速仪的高速摄像机拍摄喷雾照片,测量雾滴速度,结果显示,在3种不同的液体流量工况下,随着气体流量从250 L/min增加至350 L/min,对应的雾滴速度均近似以0.04的增长率上升,最小值为8.5 m/s,最大值为16.0 m/s。在假设细水雾雾滴形状为球状时,雾动量关系式由雾滴质量与速度的乘积得到。选取雾滴速度最大值代入公式,得到单个雾滴在不同气液流量下的雾动量变化曲线,发现当气体流量为250 L/min、液体流量为1.0 L/min时,单个雾滴动量达到最大值,为3.6×10-8 kg·m/s。通过实验研究不同气液流量对低压双流体细水雾雾场特性的影响,得出以下结论:当液体流量不变,气体流量从250 L/min以25 L/min的变化率增加至350 L/min时,雾滴粒径和雾动量逐渐减小,而雾滴速度和雾通量逐渐增加;当气体流量不变,液体流量从0.5 L/min以0.25 L/min的变化率增加至1.0 L/min时,雾滴粒径、雾动量和雾通量均逐渐增大,而雾滴速度逐渐减小。对于单个雾滴,雾动量取决于雾滴粒径的大小;而对于喷头喷出的所有雾滴,雾滴速度决定了整体雾动量的大小。今后课题将进行细水雾灭火实验,探究达到最佳灭火效果的气液流量。结论可用于飞机货舱细水雾灭火系统的设计与改进,为飞机防火系统一些参数的设置提供了实验和理论基础。 相似文献
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细水雾喷嘴是细水雾灭火系统的关键部件。本文主要采用激光多普勒测试仪(LDV)和相位多普勒粒子测量仪(PDPA)对一种旋流式喷嘴进行雾化实验研究。通过实验得到了不同测试压力下,喷嘴的流量、流量特性系数K、雾化锥角θ、水平射程、索特尔平均粒径(SMD)和粒子轴向速度的分布情况,最后得到了这几个参数随测试压力的变化关系。所测试的细水雾灭火喷头具有较大的轴向动量和径向动量,有利于扑灭深位火灾和扩大灭火范围。 相似文献
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采用高压细水雾灭火系统,以障碍物较多的商场、超市火灾为研究对象,分析在存在障碍物遮挡的条件下火灾中产生辐射热的变化规律。相同燃烧方式下变换细水雾工作压力测量辐射热通量变化。实验结果表明:燃烧组件单侧敞开燃烧时产生的辐射热较全敞开时的辐射热强;细水雾控火效果明显,但将火焰熄灭需一定的时间;细水雾系统压力过大时雾滴直径小,容易蒸发或被吹散,难以达到燃烧物表面;细水雾系统压力太小雾滴速度不足,难以发挥作用。 相似文献
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Zhigang Liu Andrew K. Kim Don Carpenter J. M. Kanabus-Kaminska Ping-Li Yen 《Fire Technology》2004,40(4):309-333
A series of full-scale experiments were conducted in a mock-up commercial cooking area to study extinguishing mechanisms and effectiveness of water mist against cooking oil fires. The impact of water mist characteristics, such as spray angle, droplet size, flow rate, discharge pressure and type of nozzle, on the effectiveness of water mist against cooking oil fires was investigated. A series of oil splash experiments were also conducted to determine if the oil was splashed by water mist. In addition, the change in oil composition during heating and fire suppression was determined using Fourier Transform Infrared (FTIR) technique.The study showed that cooking oil fires were very difficult to extinguish, because they burned at high temperature and re-ignited easily due to changes in oil composition during heating and fire suppression. The water mist systems developed in the present work effectively extinguished cooking oil fires and prevented them from re-ignition. The spray angle, discharge pressure, and water flow rate were important factors to determine the effectiveness of water mist in extinguishing cooking oil fires. 相似文献
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世界各国都在致力于新的消防技术研究,细水雾灭火以其高效、环保的特点,已经成为最具有发展潜力的哈龙替代技术和国际火灾科学前沿的研究热点之一。在军船领域。欧美发达国家的细水雾灭火系统已在舰船上得到应用,为此,国内正在进行这方面的研究。 相似文献
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E. Blanchard P. Boulet P. Fromy S. Desanghere P. Carlotti J. P. Vantelon J. P. Garo 《Fire Technology》2014,50(3):565-587
The paper deals with interaction between water mist and hot gases in a longitudinally ventilated tunnel. The work aims at understanding the interaction of mist, smoke and ventilation.The study is based on one intermediate tunnel test and an extensive use of the computational code Fire Dynamics Simulator (FDS, NIST). The approach consists first of reconstructing the test with the CFD code by defining the relevant numerical parameters to accurately model the involved water mist system. Then, it consists of handling from the local data the complicated flows generated by the water mist flooding on the one hand and by fire and ventilation on the other hand. The last stage consists in quantifying each mechanism involved in interaction between water mist and hot gases. There are three main results in this study. Firstly, the CFD code prediction is also evaluated in this configuration, with and without water mist. Before the mist system activation, the agreement is satisfactory for gas temperatures and heat flux. After the activation time, the CFD code predicts well the thermal environment and in particular its stratification. Secondly, water mist plays a strong thermal role since in the test studied, roughly half of the heat released by fire is absorbed by water droplets. Thirdly, heat transfer from gaseous phase to droplets is the main mechanism involved (73%). The remaining heat absorbed by droplets results from tunnel surface cooling which represents (9%) and radiative attenuation (18%). 相似文献