考虑辐射影响的接触传热模型与分析

应用GW统计接触模型,建立了粗糙表面之间的接触导热模型.与实验数据的对比分析表明:该模型能够正确地反映接触导热现象.在此基础上,对接触表面进行了合理的简化,建立了接触界面间的辐射传热模型.数值计算表明:当接触表面的温度高于400K时,辐射的影响已不可忽略;载荷对接触导热热导的影响明显大于对辐射热导的影响,导热热导随载荷的增大迅速增大,而辐射热导以及等效辐射系数均随载荷的增大有所减小,这主要是由接触界面的空隙面积减少造成的;在接触面几何参数中,粗糙峰等效斜率对等效辐射系数起着主导作用,在相同的量纲1的载荷情况下,粗糙峰等效斜率越小,等效辐射系数越大;通过对本文提出的等效辐射系数的误差检验,结果表明其最大相对误差为10^-3数量级,说明等效辐射系数仅仅为接触界面黑度、几何特性和接触载荷的函数,而与接触界面温度水平和温差无关,同时也间接证明了本文提出的等效辐射系数可以较为合理地描述接触界面间的辐射换热强度.

Mathematical model and analysis of contact heat transfer with radiation

A mathematical model of contact heat transfer was build by the GW statistic contact model, and the results agree well with experimental data. By simplifying the rough interfaces, a model of radiation heat transfer between interfaces was constructed. The numerical results indicate that the effect of radiation heat transfer can not be neglected when the temperature of interfaces above 400 K. Nondimensional contact load has a larger influence on the conductive than the radiant conductivity, and for the non-contact area decreasing as the non-dimensional contact load increasing, the conductive conductivity increasing quickly and the radiant conductivity decreasing slowly. The influence of asperity slope on the equivalent radiation coefficient is the most important one among the geometric parameters of interfaces. At the same non-dimensional contact load, the smaller asperity slope the higher equivalent radiation coefficient. The numerical error-test of equivalent radiation coefficient shows that the order of the max relative error is 10^-3. Within the range of this paper, the equivalent radiation coefficient is only the function of interfaces' character and contact load. It has nothing to do with the temperature and temperature difference of interfaces. The equivalent radiation coefficient is an appropriate parameter to express the radiation intensity in contact heat transfer.