This paper presents the development of a thin filament pyrometry method to characterize the time-varying temperature field in a medium-scale pool fire burning in a quiescent environment. A digital camera with optical filters and zoom lens was used to record the high temperature emission intensity of 14 µm diameter, silicon-carbide filaments oriented horizontally at various heights above the center of a steadily burning 0.30 m diameter methyl alcohol (methanol; CH 3 OH) pool fire. Experiments collected 30 Hz video of the planar filament array. In a separate experiment, a 50 µm diameter thermocouple was used to acquire independent temperature measurements in the high temperature zone of the fire. A correlation was developed between the probability density functions of the radiation-corrected thermocouple measurements and the camera grayscale pixel intensity of the filaments. This arrangement enables measurement of the time-varying temperature field over a temperature range from about 1150 K to 1900 K with a spatial resolution of 160 µm, a temporal resolution of 0.033 s, and an expanded uncertainty of about 150 K (at a mean temperature of 1300 K). Measurements of the grayscale pixel intensities of the filaments were obtained. False color maps of the temperature field were produced to characterize the high temperature field as a function of time. Using statistical analysis, the local time-averaged temperatures and their variance for each location on the filaments were determined. Time-averaged temperatures were compared favorably to previously reported measurements. The dominant frequency of the puffing fire was determined. The temperature field time series was transformed to consider its character during consecutive phases of the fire’s puffing cycle. The analysis emphasizes the cyclic nature of a pool fire, providing insight on its complex dynamic structure.

中文翻译：

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中等规模池火中的细丝高温场测量

本文介绍了一种用于表征在静止环境中燃烧的中等规模池火中随时间变化的温度场的细丝高温计方法的发展。使用带有滤光片和变焦镜头的数码相机记录了直径为 14 µm 的碳化硅细丝的高温发射强度，碳化硅细丝在稳定燃烧的直径为 0.30 m 的甲醇（甲醇；CH 3 OH ) 池火。实验收集了平面灯丝阵列的 30 Hz 视频。在单独的实验中，使用 50 µm 直径的热电偶在火灾的高温区获取独立的温度测量值。辐射校正热电偶测量的概率密度函数与灯丝的相机灰度像素强度之间建立了相关性。这种布置能够测量约 1150 K 至 1900 K 温度范围内的时变温度场，空间分辨率为 160 µm，时间分辨率为 0.033 s，扩展不确定度约为 150 K（在平均温度下） 1300 K）。获得了细丝的灰度像素强度的测量值。制作了温度场的假彩色图以将高温场表征为时间的函数。使用统计分析，确定了灯丝上每个位置的局部时间平均温度及其方差。时间平均温度与先前报告的测量值进行了比较。确定了喷火的主要频率。转换温度场时间序列以考虑其在火灾喷发周期的连续阶段的特征。分析强调了池火的循环性质，提供了对其复杂动态结构的洞察。