A three-dimensional fractal theory based on thermal contact conductance model of rough surfaces
A three-dimensional fractal theory based on thermal contact conductance model of rough surfaces
复制标题
DOI：
10.1177/0954408917727198
复制
发表时间：
2018-10
期刊：
影响因子：
--
通讯作者：
Yongsheng Zhao;C. Fang;L. Cai;Zhifeng Liu
中科院分区：
文献类型：
--
作者：
Yongsheng Zhao;C. Fang;L. Cai;Zhifeng Liu
接触导热是传热学中的一个重要问题。本文提出了一种基于接触热导模型的三维分形理论。接触表面形貌具有分形特征，由分形参数决定。微尺度下的微凸体被认为是弹性、弹塑性或塑性变形。基于赫兹接触理论，可以得到微凸体的真实的接触面积。它被认为是由许多离散的和平行的微接触圆柱的粗糙接触表面。因此，表面粗糙度的接触热导由微接触的热收缩热导和微间隙的空气介质热导组成。粗糙表面的接触热导可以通过微凸体积分计算。设计了一个环形界面的实验装置来验证所提出的接触导热模型。对具有不同分形维数D和分形粗糙度参数G的三种材料进行接触热导分析。结果表明，微凸体的弹塑性变形会影响接触热导，在较低接触载荷下，差距热导不可忽略。该模型可为传热工程应用提供理论依据。
The thermal contact conductance is an important problem in the field of heat transfer. In this research, a three-dimensional fractal theory based on the thermal contact conductance model is presented. The topography of the contact surfaces was fractal featured and determined by fractal parameters. The asperities in the microscale were considered as elastic, elastic-plastic, or plastic deformations. The real contact area of the asperities could be obtained based on the Hertz contact theory. It was assumed that the rough contact surface was composed of numerous discrete and parallel microcontact cylinders. Consequently, the thermal contact conductance of the surface roughness was composed of the thermal constriction conductance of microcontacts and the air medium thermal conductance of microgaps. The thermal contact conductance of rough surfaces could be calculated by the microasperities integration. An experimental set-up with annular interface was designed to verify the presented thermal contact conductance model. Three materials were used for the thermal contact conductance analysis with different fractal dimensions D and fractal roughness parameters G. The numerical results demonstrated that the thermal contact conductance could be affected by the elastic-plastic deformation of the asperities and the gap thermal conductance should not be ignored under the lower contact load. The presented model would provide a theoretical basis for thermal transfer engineering application.