用分形理论研究低温条件下Al-Al界面间的接触导热现象

Using Fractal Theory to Study Heat Transfer between Al-Al Interfaces at Cryogenic Temperatures and Vacuum

界面形貌是固体界面间接触导热的最主要影响因素 ,传统的形貌表征参数与仪器的分辨率和取样长度密切相关 ,因而基于这些参数的常规接触导热模型显然是尺度相关的。分形网络模型利用粗糙表面处处连续却不可微的分形特征 ,采用与尺度无关的分形参数 ,揭示了接触导热的本质 ,为准确预测接触热导开辟了一条新的途径。实验测定了粗糙表面的分形参数和低温条件下 Al50 52 - Al50 52界面间的接触热导 ,将接触热导的实验值与分形网络模型的预测结果进行了比较 ,并就接触热导与压力、分形参数和温度之间的关系进行了分析 ,指出分形网络模型的预测精度与分形参数相关联。

Micro-topography is the main factor influencing thermal contact conductance (TCC) between solid interface. Previous studies have shown that traditional roughness parameters are scale-dependent, so the TCC theoretical models based on these parameters are also scale-dependent. The fractal network model uses rough surface fractal parameters, which are irrelevant to instrumental resolution, and reveals the intrinsic properties of thermal contact. In this paper, the cryogenic TCC values have been measured across four pairs of Al5052-Al5052 specimens. The fractal network model has been used to predict TCC value as a function of contact pressure and surface fractal parameters. The measured and predicted values have been presented and compared. The relationship between TCC values and contact pressure, interface temperature, fractal parameters has been analyzed. And it is indicated that the prediction precision of network model is related to fractal parameters.