Heat Transfer in Translucent Thermal Barrier Coatings of Turbine Engine

Some of thermal barrier materials for coating in aeroengine,such as zirconia and ceramic,are partially transparent to thermal radiation.So it is necessary to estimate quantitatively the radiation effect in the thermal analysis of turbine engine under high temperature.In this paper,various surface radiative characteristics are considered including opaque (with soot) and semitransparent (without soot) coating surfaces,specular and diffuse reflections.The radiative transfer coefficients of the absorbing and isotropic scattering coatings are derived by the ray tracing/node analysis method.The transient coupled radiative and conductive heat transfer in the coatings are numerically simulated by the radiative transfer coefficients in combination with the full implicit control volume method.The radiative properties of the coatings are modelled by two or four spectral bands.The analysis includes the effects of the opaque surface emissivity,the coating thickness,and the surface radiative characteristics on the temperature distributions and heat flux densities.