多层高温隔热结构的传热特性

Heat Transfer Characteristics of High Temperature Multilayer Thermal Insulations

建立了高温多层隔热结构传热计算模型,采用蒙特卡罗方法模拟每个半透明隔热材料层内的一维辐射传递,采用有限体积法对多层隔热结构辐射导热耦合换热能量方程进行求解,对多层隔热结构的瞬态传热及热响应进行了数值模拟分析,研究了反射屏个数等因素的影响。结果表明,反射屏对多层结构隔热性能的影响取决于隔热材料的辐射特性与导热性能,当隔热材料衰减系数小时,将屏布置于高温区可提高隔热性能,当衰减系数大时,反射屏布置在低温区进行蓄热则更加有利。

High temperature multilayer thermal insulations have wide application in thermal protection technologies for hypersonic vehicles.Computational model of the heat transfer in the materials was established by the MCM for the one dimensional radiative transfer in each semitransparent insulation layer and by the FVM for the heat transfer of combined radiation and conduction in the multilayer materials.The transient heat transfer and thermal response of the multilayer insulations were numerically simulated and analyzed.Influencing factors including screen numbers,screens layout,emittance etc were analyzed.Results obtained show that both radiation and conduction properties of the insulation material influence the insulting performance of the multilayer structure.Densely distributed foils in high temperature zone can improve transient insulating performance when extinction coefficient of the insulation material is relatively small.Otherwise foils in low temperature zone are preferred for insulations with large extinction coefficient to increase heat storage capability of the multilayer structure.