Sandia Heat Flux Gauge Thermal Response and Uncertainty Models
Sandia Heat Flux Gauge Thermal Response and Uncertainty Models
复制标题
桑迪亚热通量计热响应和不确定性模型
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
W. Gill
中科院分区：
文献类型：
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作者：
T. Blanchat;L. Humphries;W. Gill
San&a热通量计（HFG）是一种坚固耐用、经济高效的技术，用于在池火环境中进行稳态热通量测量。该技术包括通过动态热模型将薄金属板的时间-温度历史减少到入射热通量，即使该测量计用于稳态。在本报告中，对轨距的构造进行了回顾。然后提出了描述压力表对f~e环境的动态响应的热模型，并说明了如何从温度读数确定热流密度。该响应模型基于第一性原理，没有经验调整常数。提出了一个验证实验，其中压力表暴露在一个阶梯输入的辐射热通量。由热响应模型确定的入射通量与已知通量输入的比较表明，该计具有明显的时间滞后。分析了测量的不确定度，并利用实验数据建立了不确定度模型。不确定性模型包含来自17个独立来源的贡献，这些来源被松散地分类为来自不受控制的变率、缺少物理或简化假设。作为缺失物理的一部分，发现了一个经验常数来补偿规范时间滞后。由于该补偿被纳入不确定性模型而不是响应模型，因此该信息可以用于分析非稳态情况下引起的大不确定性的池火数据。对仪器的不确定度进行了简短的一般性讨论，并提出了一些建议的设计更改，以方便确定和减少测量不确定度。
The San&a Heat Flux Gauge (HFG) was developed as a rugged, cost-effective technique for performing steady state heat flux measurements in the pool fire environment. The technique involves reducing the time-temperature history of a thin metal plate to an incident heat flux via a dynamic thermal model, even though the gauge is intended for use at steady state. In this report, the construction of the gauge is reviewed. The thermal model that describes the dynamic response of the gauge to the f~e environment is then advanced and it is shown how the heat flux is determined from the temperature readings. This response model is based on first principles, with no empirically adjusted constants. A validation experiment is presented where the gauge was exposed to a step input of radiant heat flux. Comparison of the incident flux, determined from the thermal response model, with the known flux input shows that the gauge exhibits an noticeable time lag. The uncertainty of the measurement is analyzed, and an uncertainty model is put forth using the data obtained from “the experiment. The uncertainty model contains contributions from seventeen separate sources loosely categorized as being either from uncontrolled variability, missing physics, or simplifying assumptions. As part of the missing physics, an empirical constant is found that compensates for the gauge time lag. Because this compensation is incorporated into the uncertainty model instead of the response model, this information can be used to advantage in analyzing pool fire data by causing large uncertainties in non-steady state situations. A short general discussion on the uncertainty of the instrument is presented along with some suggested design changes that would facilitate the determination and reduction of the measurement uncertainty.