细水雾作用下狭长空间火灾烟气特性参数变化研究

发布时间：2018-05-18 04:22

本文选题：细水雾 + 狭长空间　；参考：《安徽理工大学》2017年硕士论文

【摘要】：狭长空间尺寸特征特殊,长宽比例较大,火灾发生后烟气纵向蔓延并迅速在空间内积聚,温度升高、浓度较大导致供氧困难,又因为狭长空间发生火灾后不易被发现的特殊性,导致人员疏散无法及时进行且疏散难度加大。以水为材料的高压细水雾作为灭火工具,在环境保护方面避免了卤代烷类火剂对臭氧层的破坏或者温室效应的加剧,并且细水雾对火灾的降温效果显著,还能对烟气颗粒产生吸附作用。因此,本文采用实验和数值模拟方法分析高压细水雾作用下狭长空间火灾烟气特性参数变化,为细水雾系统在狭长空间的广泛应用提供参考依据。分析了高压细水雾作用下火源近端和远端烟气温度变化规律。实验结果表明火源近端和远端烟气温度变化的过程为先快速下降,后较为缓慢下降。在快速下降阶段火源近端和远端烟气温度下降的原因不完全一致。近端由于高压细水雾对烟气羽流的抑制作用和降温作用。远端烟气温度下降除了上述作用,还由于水雾阻挡了一部分烟气蔓延,使得远端烟气无法通过对流和热辐射作用来补充能量。研究了高压细水雾作用下不同高度火源近端和火源远端烟气温度下降速率的变化规律。从实验结果得到火源近端和远端烟气温度下降速率随烟气层高度降低呈现减小趋势,即V3.0mV2.5mV2.0m,但是底层烟气温度下降速率(V1.5m)会出现稍高的状况。获得了高压细水雾作用下顶层烟气温度沿着纵向空间变化规律。实验得到喷雾作用下顶层烟气温度沿着空间纵向呈现指数衰减趋势,衰减曲线拟合关系式为T=l0+l1exp(-x/l2),在喷雾初期衰减幅度较明显,喷雾后期衰减幅度相对较低。得到了高压细水雾作用下O2和CO浓度变化规律。从实验数据可以看出喷雾启动后烟气中O2浓度呈现出先快速回升,后缓慢回升。CO浓度变化呈现出,先缓慢上升,后CO浓度开始迅速下降,最后CO浓度开始缓慢下降。在实验参数基础上,采用FDS分析了高压细水雾作用下烟气温度场和CO浓度随时间的变化,并将这一结果和实验结果进行了对比,发现数值软件计算结果同实验吻合度较高,能够用来展现细水雾作用下狭长空间火灾烟气参数变化规律。
[Abstract]:The long and narrow space is characterized by special size, large ratio of length to width, vertical spread of smoke and rapid accumulation in space after fire, rising temperature, high concentration of oxygen, and the particularity that is not easy to be found after fire in the long and narrow space. As a result, evacuation can not be carried out in time and the evacuation is more difficult. Using high pressure water mist as fire extinguishing tool, water mist can avoid the destruction of ozone layer or the aggravation of Greenhouse Effect caused by halogenated fire agents in environmental protection, and the effect of water mist on the cooling of fire is remarkable. It can also adsorb the smoke particles. Therefore, in this paper, the experimental and numerical simulation methods are used to analyze the variation of fire smoke characteristic parameters in narrow space under the action of high pressure water mist, which provides a reference for the wide application of water mist system in narrow space. The variation of flue gas temperature at the proximal and distal end of the fire source under the action of high pressure water mist is analyzed. The experimental results show that the temperature changes of the proximal and distal flue gas of the fire source decrease rapidly first and then slowly. The reasons for the decrease of flue gas temperature at the proximal and distal end of the fire source are not completely consistent during the rapid descent. The suppression and cooling of flue gas plume due to high pressure water mist at the proximal end. In addition to the above effects the decrease of the temperature of the far flue gas can not replenish the energy through convection and heat radiation due to the water mist blocking the spread of a part of the flue gas. Under the action of high pressure water mist, the variation of flue gas temperature drop rate at the proximal end and the distal end of the fire source with different heights was studied. From the experimental results, it is found that the decreasing rate of flue gas temperature at the proximal and distal end of the fire source decreases with the decrease of the height of the flue gas layer, that is, V3.0 MV 2.5mV 2.0 m, but the falling rate of the bottom flue gas temperature is 1.5 m). The variation of flue gas temperature along the longitudinal space under the action of high pressure water mist is obtained. The experimental results show that the top flue gas temperature shows an exponential attenuation trend along the longitudinal space under spray action. The decay curve fitting formula is T=l0 l1exp-x / L ~ (2). The attenuation amplitude is obvious at the initial stage of spray, and the attenuation amplitude is relatively low at the later stage of spray. The variation of O _ 2 and CO concentration under the action of high pressure water mist is obtained. From the experimental data, it can be seen that the concentration of O _ 2 in flue gas rises rapidly first, then slowly rises. The concentration of CO increases slowly, then CO concentration begins to decrease rapidly, and finally the concentration of CO begins to decrease slowly. On the basis of experimental parameters, the variation of flue gas temperature field and CO concentration with time under the action of high pressure water mist is analyzed by FDS, and the results are compared with the experimental results. It is found that the numerical results are in good agreement with the experimental results. It can be used to show the variation of smoke parameters in narrow space under the action of water mist.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU998.1

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