【作者】 杨春英；

【导师】 郜冶；

【作者基本信息】 哈尔滨工程大学 ， 一般力学与力学基础， 2012， 博士

【摘要】 在一个容腔的容积确定、开口尺寸也确定的小空间中，当有热释放量存在时，三者在一定的匹配比例下会产生整体高温气流按一定规律反复喷出的现象。这一现象曾经被多位学者认真研究，但是在理论上没有给予有效地被大家认可的总结，有关研究多数局限于零散的实验现象的报道和描述。近年来，各种建筑都钟爱于玻璃幕墙材料的美观、方便以及室内装修的透明敞亮，玻璃幕墙下的有开口尺寸的小空间内如果有可燃材料，就会发生整体热气流振荡的危险。特别是高层建筑的外围护玻璃幕墙，一般都有下部的安装通道和底层小空间，这些小空间内经常存放装修中使用的可燃材料，烟囱效应会使可燃热烟气迅速到达楼的上层，在一定条件下易于产生整体热气流振荡并使玻璃幕墙破坏，而玻璃破裂后会掉落并可能伤及周围人群。本文系统地研究了有限侧向开口小空间热气流低频振荡的基础实验现象和工程理论计算方法，并对典型实验结果给出了理论预示的基本计算公式。在此基础上，研究了高温热气流从玻璃侧向扑打时的基本实验，并和本文提出的理论分析结果和数值模拟结果进行了比较。在ISO9705火灾标准实验台上，对四种典型开口、平均热释放率为650kW、大约350s燃烧时间条件下，对热气流喘振的发生、维持和强弱程度进行了实验研究。给出了该实验条件下振荡频率的范围在0.1～0.25Hz，并和本文由质量和能量方程推导出的基本振荡频率的关系式进行了比较。该推导的关系式还和以往其他学者的实验结果进行了比较和修正。实验记录图像显示了开口尺寸和位置的不同、开口空间内和外界环境温度差别和有浮力作用下产生的整体振荡的基本情况。本文把小空间内高温热气流引起的振荡按照压力驱动和浮力驱动进行二类数学模型的建立，给出了振荡频率f，振荡增长率α和振荡响应能力函数R m之间的关系。本文确定了浮力驱动作用下的特征滞后时间和压力驱动下的特征滞后时间。提出在小空间压力驱动流和浮力驱动流的振荡频率与室内平均温度、出口面积、空间尺寸之前的关系。通过对玻璃平板的专门实验，本文给出了典型实验情况下火焰和高温气流扑打玻璃板表面一侧温度变化平面上二维分布的函数。给出了温度分布变化情况下，热张力和热弯矩以及位移在不同的约束条件下的解析解。为确定玻璃破裂临界应力发生的位置、破碎时间的预示提供了理论计算基础。采用ANSYS软件，对玻璃平板一侧有高温气流扑打且温度场不均匀分布，随时间变化的热气流冲击进行了数值模拟，给出了在不同热冲击情况下玻璃平板热应力和热弯矩变化的数值结果。根据玻璃平板的温度分布以及周围边框的典型四种约束条件，给出不同时间后玻璃内部热应力和位移分布，可以观察到哪一种约束形式下应力和位移更大一些，从而确定约束形式对延长玻璃破裂时间的影响。同时比较了四种约束形式下哪种情况玻璃受到的拉应力最小，为工程施工指明了设计方向。更多还原

【Abstract】 For a small opening space which has the determined cavity volume and thedetermined size, when existing the release of heat, in a certain proportion the threematches will produce the phenomenon in which the overall heat flow emits repeatedlyaccording to certain rules. This phenomenon has been carefully studied by a numberof scholars, but in theory it has not get the recognized conclusion, and the relevantresearches is largely confined to reports and description of scattered experimentalphenomena.In recent years, various buildings tend to glass curtain wall materials because ofthe beauty, convenient and the transparent light and spacious interior. However ifthere is combustible material in the small space under a glass wall, the overall heatflow may be at the risk of oscillation. Especially the outer enclosure glass curtainwalls of high-rise building, it generally have lower installation channel and the smallspace in bottom, and in these small spaces often there are combustible materials usedin decoration. Combustible hot flue gas will rapidly reach the upper floor because ofthe chimney effect. In certain conditions, the overall heat flow oscillations are proneto make the glass curtain wall damaged, and the broken glass may injure people.In this paper, systematic study of basic experimental phenomena and engineeringtheory calculations for low-frequency oscillatory heat flow in a small space withlimited lateral opening are done, and the theory indication basic formula for typicalexperiments also are obtained. Based on this study, the basic experiments of the singleheat flow lateral swatting at the glass is taken, and the comparison between theoreticalanalysis results and simulation results is made.On the ISO9705fire standard laboratory bench, the experimentation for theoccurrence, maintenance and the strength of hot air oscillation is done, whichaccording to four typical openings, average heat release rate of650kW, and theburning time of about350s. The oscillation frequency under the experimentalconditions range of0.1~0.25Hz and the result are modified and compared to thefundamental oscillation frequency derived from mass and energy equations. It alsocompares to previous experimental results of other scholars. Recorded image showsthe basic situation of overall oscillation with the different openings sizes, different locations, different temperature difference between inside and outside, and if with theeffect of buoyant.Next in this paper, two types of mathematical models for oscillation in smallspace caused by high-temperature hot are constructed, the relationship amongoscillation frequency f, oscillation rate α and the function of oscillation responsecapability Rmis given. It also determines the characteristics lag time with the effect ofbuoyancy-driven and the characteristics lag time with the effect of pressure-driven.The relationship among oscillation frequency, average indoor temperature, dischargearea and space size of pressure-driven flow and buoyancy-driven flow in a smallspace are obtained.The paper shows the function of two-dimension distribution on the temperaturechange plane when the flame and high temperature air swatting the side of the glasssurface in typical experimental conditions. The analytical solutions of thermal stress,hot bending moments and displacement under the condition that different constraintsand changes in temperature distribution are given. It provides the basis of theoreticalcalculations for the position fracture critical stress occurring and the indicating forbroken time. According to the temperature distribution and the four kinds of typicalconstraints border around the glass plate, it gives the heat stress and displacementdistribution within the glass in different time. It can be observed in which constraintform stress and displacement is much larger, so it will determine the impact ofconstraint form to extension of glass broken time. It uses ANSYS to carry onnumerical simulation for the impact on glass plate of hot air varying with time. Andthen it gets the numerical result about the glass plate heat stress and heat bendingmoment changes in the different case of heat shocking. It also compares fourconstraints and obtained in which form the tensile stress of the glass by the minimumin order to specify the direction for construction.更多还原