导热-辐射耦合传热的多尺度分析和数值模型

Multiscale analysis and numerical model for coupled conduction-radiation heat transfer

复合材料高温传热特性的准确预测对飞行器热防护结构的设计有重要意义,相关模型也是国家数值风洞工程中多相多介质计算模型的重要组成部分。针对周期性结构复合材料的高温传热问题,利用多尺度渐进分析方法,对包含导热方程和辐射传输方程的导热-辐射耦合传热模型开展了研究。建立了表征单元尺度模型及宏观平均导热-辐射耦合传热模型,获得了材料宏观等效导热系数与表征单元模型间的关系,发现宏观等效辐射吸收和散射等系数可通过表征单元内的体积平均求取。结合有限容积方法与格子Boltzmann方法,建立了复合材料导热-辐射耦合传热多尺度数值模型。采用二维常物性材料传热过程的模拟验证了多尺度模型的有效性,结果表明所建立的多尺度模型能够对温度场给出准确高效的计算结果。该方法有助于为复合材料传热特性的预测提供数值手段。

Predictions of the heat transfer processes in composite materials are important for designs of thermal protection structures of hypersonic vehicles.The corresponding model is also an essential part of the multiphase-multicomponent submodel of the National Numerical Windtunnel Project.In this work,a multiscale asymptotic analysis method is used to study the problem of coupled conduction-radiation heat transfer for high temperature composite materials with periodic structures.Both the conduction equation and radiative transfer equation are analyzed.The cell problem and homogenized macroscopic conduction and radiation equations are established.The relation between effective thermal conductivity and the results of the cell problem is obtained.It is also found that the radiative absorption and scattering coefficients can be calculated from the volumetric averages in a representative element.A multiscale numerical model for conduction-radiation heat transfer in composite materials is built based on the finite volume method and the lattice Boltzmann method.The multiscale model is validated by the simulation of heat transfer in 2 Dmaterials with constant thermal properties.It is shown that the temperature fields can be effectively and accurately calculated by the multiscale model proposed.The model can be further used in the prediction of high-temperature heat transfer processes in composite materials.