Frequency response and spatial resolution of a thin foil for heat transfer measurements using infrared thermography
Frequency response and spatial resolution of a thin foil for heat transfer measurements using infrared thermography
复制标题
使用红外热成像技术进行传热测量的薄箔的频率响应和空间分辨率
DOI：
10.1016/j.ijheatmasstransfer.2009.04.019
复制
发表时间：
2009
影响因子：
5.2
通讯作者：
Hajime Nakamura
中科院分区：
文献类型：
--
作者：
Hajime Nakamura
本文提出了一种测量对流换热时空分布的技术，该技术采用电加热薄片制成的测试表面。如果测试表面的热容量足够低，则可以使用高帧率红外热像仪测量箔上的波动温度。然而，这种方法有一个固有的问题，即由于热惯性和传导，测试表面的温度在时间和空间上都有衰减。在本研究中，考虑热损失，分析了薄膜的频率响应和空间分辨率。通过引入波动频率和空间波数等无量纲变量，推导出测试表面温度的时空幅值，从而推导出两者之间的一般关系。基于这些关系，利用测量系统的控制参数，成功地制定了可检测的波动频率和空间波数的上限。这使我们能够定量地评价红外热像仪测量传热的可靠性。实际条件下的数值表明，该测量技术有望用于研究流动湍流引起的传热的时空行为。
A technique for measuring the spatio-temporal distribution of convective heat transfer has been developed using a test surface fabricated from a thin foil heated electrically. If the heat capacity of the test surface is sufficiently low, the fluctuating temperature on the foil can be measured using high-frame-rate infrared thermography. This method, however, has an inherent problem in that the temperature on the test surface attenuates both in time and space due to thermal inertia and conduction. In the present study, the frequency response and the spatial resolution of a thin foil were examined analytically considering heat losses. In order to derive general relationships, non-dimensional variables of fluctuating frequency and spatial wavenumber were introduced to formulate the temporal and spatial amplitudes of the temperature on the test surface. Based on these relationships, the upper limits on the detectable fluctuating frequency and spatial wavenumber were successfully formulated using governing parameters of the measurement system. This enables us to evaluate quantitatively the reliability of the heat transfer measurement by infrared thermography. The values, evaluated here for the practical conditions, indicated that this measurement technique is promising for investigating the spatio-temporal behavior of heat transfer caused by flow turbulence.