【作者】 周勇；

【导师】 张和平；

【作者基本信息】 中国科学技术大学 ， 安全技术及工程， 2009， 博士

【摘要】 壁面装饰材料垂直火蔓延是室内火灾发展的重要途径,水喷雾是有效的火蔓延抑制手段。本文选用四种不同厚度的杉木板（10mm,12mm,15mm,18mm）,分别开展了热失重分析实验和在ISO9705标准燃烧室开展了全尺寸实验,主要研究不同厚度的杉木板垂直壁面火蔓延特性以及侧向水喷雾对其的抑制作用,并在前人的基础上改进了侧向水喷雾临界水施加率的计算方法,在实验中验证。从微观的角度对杉木材进行热失重分析实验研究。利用热重-差热（TG-DTA）联用分析仪研究杉木材的热解行为,分析材料在受热过程中结构和成分的变化,考虑升温速率对热解过程的影响,最终依据国际标准局（ISO）TG曲线关键温度表示法确定热解特征温度,为后面划分木板预热区与热解区提供实验依据。在杉木板垂直壁面火蔓延的研究中,采用了先进的测量仪器红外热像仪,通过在红外热像仪实时观测窗口中设置若干条等距等宽的刻度线,记下每条刻度线上平均温度达到杉木材热解特征温度的时间,得到杉木板壁面垂直向上火蔓延位移数据。根据火蔓延位移数据,计算出火蔓延平均速率,从而得到杉木板垂直火蔓延规律:杉木板垂直火蔓延分为三个阶段——点燃阶段、过渡阶段和发展阶段;另外总结出厚度对杉木板垂直火蔓延的影响。利用曲线拟合的数值处理方法,拟合出火蔓延位移和时间的函数。根据位移和速率的基本关系式,对火蔓延位移函数求导,得到火蔓延瞬时速率的函数,并通过matlab绘制出火蔓延位移和瞬时速率的曲线图。将数字图像处理方法运用到实验中,通过读取摄像机拍摄的杉木板垂直火蔓延的视频,实时获取火焰高度,为后续计算临界水施加率提供参数。首先对单帧图像进行阈值分割,消除背景噪声,提取火焰目标;然后计算出火焰的像素高度,再对其进行标定,得到实际高度;最后对每一秒取15帧图像中的火焰高度求平均值,消除因为火焰跳动带来的误差。侧向水喷雾作用于木板预热区的情况下,研究了四种不同厚度杉木板贴面固定在墙壁时的燃烧特性,并测量了热释放速率、木板表面温度以及CO/CO₂浓度。在红外热像仪中标出水喷雾作用区的最底端界限,并依据杉木材热解特征温度设定等温线280℃～300℃,当等温线蔓延至最底端界限时开始喷水,此时水喷雾呛米饔迷谏寄景宓脑と惹?调整喷头压力使得等温线既不向上蔓延也不向下回落,此时即为预热区的侧向水喷雾临界水施加压力,结合喷头相关喷流特性得到临界水施加率实验值。改进了作用在预热区的侧向水喷雾临界水施加率计算方法,主要是从预热区和热解区的判据和计算方法中的重要参数两方面改进,并引入了厚度因子。计算出4种厚度杉木板的临界水施加率理论值,与临界水施加率实验值进行对比,给出实验验证。更多还原

【Abstract】 Lining material is an important approach of flame spread while water spray is an effective way to control flame spread.China fir boards of four different thickness （10mm,12mm,15mm,18mm） were chosen to conduct the thermal gravimetric analysis experiments and Full scale experiments according with ISO9705 standard. The behavior of the china fir board vertical flame spread and its suppression with lateral water spray were studied.Moreover,the calculation method of lateral critical water flow rate was improved and was verified.The experiments were conducted to make the thermal gravimetric analysis of the china fir board from the microcosmic angel.The pyrolysis behavior of the china fir board and the changes of construction and ingredients of the material were studied using the TG-DTA analyzer.Considering the effect of heating rate on the prolysis process,according to the ISO TG curve key temperature representation,the pyrolysis characteristic temperature was determined to divide the preheat zone and prolysis zone.The infrared thermography was used to research the relation of china fir board vertical flame spread.By setting several equidistant scale marks with equal length in the real-time observation window of the infrared thermography,the time when the average temperature on every scale mark arise to the prolysis characteristic temperature was recorded to get the data of displacement of flame spread.Based on the data of displacement of flame spread the average velocity of flame spread was calculated.So the conclusion is:the vertical flame spread process of china fir board is divided into three stages:kindling stage,transition stage and developing stage.And the effect of thickness on the vertical flame spread was concluded.The method of curve fitting was selected to get the function of displacement of flame spread.Based on the relationship of velocity and displacement,the function of displacement of flame spread was differentiated to get the function of velocity of flame spread.The curves of the function of displacement of flame spread and the function of velocity of flame spread were plotted in matlab. The image processing method was introduced into the experiments.Flame height was acquired by the video frequency taken by the camera to give the parameters of lateral critical water flow rate.First,single frame image was processed by threshold segmentation and background noise reduction to extract the fire target;second,the height of the fire was calculated and calibrated;finally,to eliminate the errors of flame flutter,15 flames images in one second were chose to calculate the mean flame height.Full scale experiments were conducted according with ISO9705 standard to study the fire behavior of four china fir board of different thickness on the wall when the water spray acted on the preheat zone of the board,and the parameters such as heat release rate,board surface temperature and concentration of CO/CO₂ were measured.The bottom limit of the action area of the water spray was marked in the infrared thermography and the isothermal line（280℃～300℃） were set according to the pyrolysis characteristic temperature.When the isothermal line spread to the bottom limit the water spray started which acted on the preheat china fir board to the moment.If the pressure of the sprayer was adjusted to keep the isothermal line neither rising nor falling,it was the lateral critical water flow pressure of the preheat zone.So the experimental value of the lateral critical water flow rate could be calculated according to the jet characteristics of the sprayer.The calculation method of lateral critical water flow rate on the preheat zone of the china fir board was improved:The parameters such as fire height and heat release rate was modified;the criterion of preheat zone and prolysis zone was proposed;the thickness factor was added.The computation value of the lateral critical water flow rate of four china fir board with different thickness was calculated to compare with the experiment data.The result proved that the experimental data matched well with the model values.更多还原