火灾场景下细水雾幕保护窗玻璃的实验研究

发布时间：2018-01-26 00:13

本文关键词： 细水雾幕玻璃保护工作压力细水雾幕厚度启动时间水膜　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：窗玻璃在火灾条件下极易受到过量热流的影响而发生破裂和脱落,形成新的开口,强化火灾区域通风,造成火势急剧增长,甚至溢出并跨区域蔓延,影响人员逃生。因此,研究防止玻璃在火灾条件下受过量热流影响而破裂脱落的技术是建筑火灾防控的重要内容之一。本文针对这一背景提出了一种采用细水雾幕阻隔火焰热辐射保护玻璃的方法,开展了细水雾幕对浮法玻璃保护效果的实验研究。本文首先考虑了不同细水雾幕工作压力和不同细水雾幕启动时间对细水雾幕保护玻璃效果的影响,同时与传统水膜对浮法玻璃保护效果进行对比。结果表明,火源与保护装置同时启动,细水雾幕和水膜都能将玻璃首次破裂时间延长。本文实验条件下,火源与保护装置同时启动,细水雾幕和水膜都能将玻璃首次破裂时间由150 s延长到600 s。相同的实验条件及流量下,细水雾幕比水膜表现出更好的保护效果。细水雾幕工作压力越大,保护效果越好,但当压力超过1.0 MPa持续提高细水雾幕压力,保护效果变化不明显。当玻璃表面温度达到一定值后启动分隔型细水雾幕,可以发现随着细水雾幕启动时间的延迟,其保护效果与同时启动的工况相比变差。当玻璃表面温度达到一定值后启动喷洒型细水雾幕,细水雾幕对窗玻璃保护效果不受影响,仍能有效延长浮法玻璃首次破裂时间。但延迟启动水膜,玻璃首次破裂时间与同时启动工况相比明显缩短。本文还通过改变细水雾幕厚度,详细分析不同厚度细水雾幕保护下玻璃首次破裂时间、玻璃内部最大温差及玻璃背火面辐射热通量等关键参数。结果表明,细水雾幕厚度对玻璃破裂有显著影响:压力一定,细水雾幕厚度越厚,保护效果越好,玻璃首次破裂所需时间越长。同时本文针对细水雾幕对热辐射的衰减作用,理论计算了不同厚度细水雾幕作用下的透射率和辐射衰减效率,发现随着细水雾幕厚度增加,辐射衰减效果增强,但当细水雾幕厚度增加到一定值(本文为7.5 cm),继续增加细水雾幕厚度,其衰减热辐射效果无明显改善。此外,在理论计算细水雾幕透射率基础上,通过分析经典的玻璃破裂时间理论预测模型,建立了细水雾幕保护下玻璃首次破裂时间的预测模型,并将预测结果与实验结果进行对比,发现结果呈现较好的一致性。
[Abstract]:Window glass is easily affected by excessive heat flux to rupture and fall off under fire conditions, forming new openings, strengthening ventilation in the fire area, resulting in a sharp increase of fire intensity, even overflow and spread across regions. Affecting the escape of personnel. To study the technology of preventing glass from breaking and falling off under the influence of excessive heat flux is one of the important contents of building fire prevention and control. In view of this background, this paper puts forward a kind of protection against flame heat radiation with water mist curtain. The method of glass. The effect of water mist curtain on the protection of float glass was studied. Firstly, the effects of different working pressure of water mist curtain and different starting time of water mist curtain on the protection effect of water mist curtain were considered. At the same time, compared with the traditional water film to float glass protection effect. The results show that the fire source and protection device start at the same time, the water mist curtain and water film can prolong the first time of glass rupture. At the same time, the water mist curtain and water film can extend the first rupture time of glass from 150 s to 600 s. Under the same experimental conditions and flow rate. The higher the working pressure of water mist curtain, the better the protection effect, but when the pressure is more than 1. 0 MPa, the water mist screen pressure will continue to increase. When the surface temperature of the glass reaches a certain value, the separated water mist curtain can be started, it can be found that the delay of the starting time of the water mist curtain can be found. When the surface temperature of the glass reaches a certain value, the spray water mist curtain is started, and the water mist curtain does not affect the window glass protection effect. The initial rupture time of float glass can still be prolonged effectively. However, when the water film is delayed to start, the first rupture time of glass can be shortened obviously compared with the simultaneous starting condition. The thickness of water mist curtain is also changed in this paper. The key parameters, such as the first rupture time of glass under the protection of water mist curtain with different thickness, the maximum temperature difference inside the glass and the radiation heat flux on the back of the glass fire surface, are analyzed in detail. The thickness of water mist curtain has a significant effect on glass rupture: the thickness of water mist curtain is thicker, the better the protection effect is. The more time it takes to break the glass for the first time, at the same time, the transmittance and radiation attenuation efficiency of water mist curtain with different thickness are calculated theoretically for the attenuation effect of water mist curtain on thermal radiation. It is found that the radiation attenuation effect increases with the increase of the thickness of the water mist curtain, but when the thickness of the water mist curtain increases to a certain value (7.5 cm in this paper, the thickness of the water mist curtain continues to increase. In addition, on the basis of theoretical calculation of transmittance of water mist curtain, the classical prediction model of glass rupture time is analyzed. The prediction model of the first rupture time of glass under the protection of water mist curtain is established and the results are compared with the experimental results. It is found that the results are in good agreement with the experimental results.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ171.721;TU998.1

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