气动加热下高温陶瓷材料的红外辐射机理与特性

从分析材料内部热辐射与导热耦合传热温度场、表面反射及折射之间的内在关系出发,建立了气动加热下高温陶瓷材料的红外辐射模型.采用控制容积法结合蒙特卡罗法和谱带模型,数值模拟了红外辐射能在材料内部的传递及出射过程.引入介质影响因子,分析了材料的红外辐射机理和外部气动热流对材料红外辐射特性的影响.结果表明,高温陶瓷材料内部热辐射的光谱选择性与温度场的耦合,导致高温陶瓷材料的红外发射率随气动热流变化而变化.由于陶瓷材料在紫外和中远红外谱带范围对辐射的吸收非常强,而在近红外和可见光谱带范围对辐射吸收较弱,随气动热流密度增大,对陶瓷材料表面红外辐射产生贡献的内部热辐射区域增大,但材料的红外发射率降低.

Infrared Radiation of High Temperature Ceramics Under Aerodynamic Heating

An infrared radiation model for high temperature ceramics under aerodynamic heating condition was developed by analyzing the relationship between the internal thermal radiation. the temperature field of heat transfer, as well as the reflection and refraction at surface. The control volume method combined with the Monte Carlo method and spectral model were used to simulate the radiation heat transfer in the ceramics and outgoing process. The medium effect factor was introduced to analyze the infrared radiation mechanism of the material and the effects of aerodynamic heating on the infrared characteristics. The results show that the coupling of spectral selectivity of thermal radiation inside the high temperature ceramics of the temperature field results in the dependence of material infrared emissivity on the heat flux of aerodynamic heating. The high temperature ceramics absorbs radiation in the ultraviolet, mid-infrared, and the far infrared intensively while absorbs radiation in visible spectra and near infrared weakly. So, the effective region inside the material, where the thermal radiation of medium can contribute to the infrared emission of the material surface, enlarges will the increase of aerodynamic heating, but the infrared emissivity of material decreases.