Evaluation of Directional Flame Thermometer for Real-Time Inversion of Heat Flux
Evaluation of Directional Flame Thermometer for Real-Time Inversion of Heat Flux
复制标题
定向火焰温度计实时反演热通量的评价
DOI：
10.1115/ihtc14-22917
复制
发表时间：
2010
期刊：
影响因子：
3.4
通讯作者：
O. Ezekoye
中科院分区：
文献类型：
--
作者：
P. Kokel;C. Weinschenk;O. Ezekoye
定向火焰温度计（DFT）通常用于测量室内火灾测试过程中的热通量。在文献和实践中，DFT的传热解决方案已被后处理。重要的是开发基于测量温度计算热通量的实时能力，因为这种能力将允许控制火灾测试炉。在这项研究中，我们表明，如果用户将接受中等误差的热通量，那么一个简单的前向解决方案的方法允许热通量测量进行实时。从本质上讲，“逆”问题是充分良好的条件，允许一个简单的解决方案。一个简单的电子表格类型的解决方案和有限差分代码被用来产生的热通量。该代码在正向和反向意义上都得到了验证。通过空间离散（dx）和时间离散（dt）的正反解的收敛性研究，验证了计算结果。逆解在空间和时间离散化中均表现出预期的收敛行为。在所有情况下，前板的解产生约5%的最大误差，其随着DFT达到稳态温度而减小。通过辐射加热器面板的实验测试，验证了正、逆模型。将逆模型的计算结果与施密特-博尔特规的测量结果进行比较。在大多数测试期间，DFT的前板热通量测量值与Schmidt-Boelter计相当好地匹配（2-6%差异）。然后，热通量用于驱动正演模拟，并将正演模型的计算结果与测试获得的实际温度数据进行比较，产生不超过4%的差异。DFT还被放置在室内火灾中，以评估其在该环境中的有效性。将DFT放置在砂燃烧器附近并进行面板火灾测试。DFT产生了合理的热通量值，但比辐射加热器面板前面的结果有更多的噪音（标准偏差为1500 W/m2，而不是400-600 W/m2）。
The Directional Flame Thermometer (DFT) is often used to measure heat flux during room fire testing. In literature and practice, heat transfer solutions for the DFT have been post processed. It is important to develop real-time capability for calculating heat flux based on measured temperatures as such capability will allow control of fire testing furnaces. In this study, we show that if a user will accept moderate errors in the heat flux, then a simple forward solution methodology allows heat flux measurements to be made in real-time. Essentially, the “inverse” problem is sufficiently well-conditioned to allow for a simple solution. Both a simple spreadsheet type solution and a finite difference code were used to generate the heat flux. The code was verified in both forward and inverse senses. The calculations were verified through a convergence study of both the forward and inverse solutions in spatial discretization (dx) and temporal discretization (dt). The inverse solution showed expected convergence behavior in both spatial and temporal discretization. In all cases, the solution for the front plate produced a maximum error of around 5%, which decreased as the DFT reached a steady state temperature. The forward and inverse models were validated through experimental testing using a radiant heater panel. The inverse model’s calculations were compared to measurements from a Schmidt-Boelter gage. The front plate heat flux measurements of the DFT matched reasonably well with the Schmidt-Boelter gage (2–6% difference) during the majority of the testing. The heat flux was then used to drive a forward simulation, and the forward model’s calculations were compared to actual temperature data acquired by the tests, producing a difference no greater than 4%. The DFT was also placed into a room fire to evaluate its effectiveness in this environment. The DFT was placed near a sand burner and in a panel fire test. The DFT produced reasonable heat flux values, but had more noise than results from those in front of the radiant heater panel (standard deviation of 1500 W/m2 compared to 400–600 W/m2 ).Copyright © 2010 by ASME