【作者】 刘航；

【导师】 李元洲；

【作者基本信息】 中国科学技术大学 ， 安全科学与工程， 2019， 硕士

【摘要】 随着国家经济建设的飞速发展,大量的复杂建筑拔地而起,很多建筑内会使用一些可燃材料,一旦燃烧,通常会伴随着大量的有毒有害烟气的产生,所以建筑火灾中的烟气控制问题是现阶段火灾防控的重点之一。现代建筑中机械排烟系统方面,规范中规定,机械排烟系统管道高度在公共建筑中不得超过50m,民用建筑中不得超过100m。我们研究了机械排烟系统管道高度对风机效果的影响,首先通过实验的方法,测量了同一机械排烟系统下不同楼层的排烟量,发现在50m和100m的管道高度下,排烟口的风速相比0m时,分别衰减了 15%和33%。之后我们通过数值模拟,发现风机风量与管道高度成线性关系,随着管道高度的增加,风机风量在不断的减少。从本文中得到的结果来看,当管道高度为50m时,风机的实际风量约为额定风量的90.1%,而当管道高度达到100m时,风机的工作风量仅为额定风量的81%。也就是说在机械排烟系统的设计中,需要提前考虑风机管道所造成的损失情况,适当的增加风机的额定风量,以满足规范中对机械排烟系统风量的要求。对于自然排烟,规范中认为除平推窗是按照是实际开口大小计算外,其他悬窗均是以开口后的投影面积计算。而实际上自然排烟窗的实际排烟效果还受到窗体类型的影响。本文通过数值模拟方法,主要研究了上悬窗和下悬窗对排烟效果的影响。我们通过改变上悬窗开口角度,发现了上悬窗主要排烟区域为窗体两侧,而上悬窗排烟效率跟开启角度正弦值为线性关系,而与窗体的长度关系不大,在此基础上提出了一种提高建筑中上悬窗排烟效率的方法。而下悬窗的模拟结果则表明,窗体开启角度大于23°时,其排烟效果基本与没有窗体遮挡时相同。更多还原

【Abstract】 With the rapid development of the country’s economic construction,a large number of complex buildings have risen from the ground.Many buildings use some combustible materials.Once burned,they are usually accompanied by a large amount of toxic and harmful fumes,so the smoke in the building fire.Control problems are one of the key points of fire prevention and control at this stage.In terms of mechanical exhaust system in modern buildings,the specification stipulates that the height of the pipe of the mechanical exhaust system shall not exceed 50m in public buildings and 100m in civil buildings.We studied the influence of the pipe height of the mechanical exhaust system on the effect of the fan.Through the experimental method,the smoke exhaustion of different floors under the same mechanical exhaust system is measured.It is found that at the pipeline heights of 50m and 100m,the wind speed of the exhaust outlet was attenuated by 15%and 33%respectively compared with 0m.After that,we found through numerical simulation that the fan air volume is linear with the pipe height.As the pipe height increases,the fan air volume are reduce continuously.From the results obtained in this paper,when the pipeline height is 50m,the actual air volume of the wind turbine is about 90.1%of the rated air volume,and when the pipeline height reaches 100m,the working air volume of the wind turbine is only 81%of the rated air volume.That is to say,in the design of the mechanical exhaust system,it is necessary to consider the loss caused by the fan pipeline in advance,and appropriately increase the rated air volume of the fan to meet the requirements of the specification for the air volume of the mechanical exhaust system.For natural smoke exhaust,the specification considers that except for the flat push window,which calculated according to the actual opening size,the other hanging windows is calculated based on the projected area after the opening.In fact,the effect of the natural smoke exhaust windows is also affected by the type.In this paper,the influence of the top-hung windows and the bottom-hung windows on the smoke exhausting effect are mainly studied by numerical simulation method.By changing the opening angle of the upper hanging window,we found that the main exhaust area of the top-hung windows is the two sides of the window,and the efficiency of the exhaust of the top-hung windows is linear with the sine value of the opening angle,but has little relationship with the length of the window.Based on this,a method for improving the efficiency of exhausting the top-hung windows in buildings are proposed.The simulation results of the bottom-hung windows show that when the opening angle of the window is greater than 23°,the smoke exhausting effect is basically the same as when there is no window occlusion.更多还原