Transient Coupled Heat Transfer In Multi-Layer Absorbing-Scattering Composite With Specular And Diffuse Reflection Properties

Semitransparent materials are widely used in industry, such as the ceramic parts of aircraft and automobile engine, the ceramic layer for insulating protection of turbine engine, the space optical windows, the fibre for insulating protection, the manufacture of optical fibre and components, and the ignition of semitransparent plastic, etc. When evaluating the thermal properties of these materials, ignoring radiation effect can cause errors.In this thesis, by using the ray tracing/node analyzing method in combination with spectral band models, the transient coupled radiative and conductive heat transfer in a three-layer and a multi-layer composite is investigated respectively. The optical properties and thermal physical properties in each layer are different from one another. The isotropic scattering and the radiative and convective boundary conditions are considered.The interfaces of the composite are semitransparent. Considering direct radiation transfer among all the layers, the physical and mathematical models are developed, which can fit four sorts of surface radiative properties and three sorts of interface reflective mode. The four sorts of surface radiative properties are: (1) both surfaces are semitransparent, (2) both surfaces are opaque, (3) the left surface is semitransparent, but the right one is opaque, (4) the left surface is opaque, but the right is semitransparent. The three sorts of interface reflective mode are: (1) specular reflection, (2) diffuse reflection, (3) both specular reflection and diffuse reflection are included.The main work in this thesis includes the following several aspects.1. The ray tracing method is extended to be applicable to the multi-layer medium. By introducing the one-layer and multi-layer radiative intensity and radiative energy quotient transfer function conceptions, and resorting to them to trace the radiative intensity and radiative energy transfer in multi-layer medium, the multi-layer ray tracing method is presented.2. The radiative transfer coefficients for specular reflection are solved. The...