Identification of thermal conductivity and radiation properties of alumina below 1300K based on wavelet decomposition

Open cell foam ceramics are a common absorbing and scattering material, which has excellent thermal transmission and mechanical strength properties and is widely used in various high-temperature industrial fields. The measurement error at high temperature makes it difficult to obtain its physical parameters. Hereto, this study establishes a radiative and conductive heat transfer model in which the thermal conductivity and extinction coefficient are dependent on temperature, and constructs an inversion model through wavelet decomposition, it is different with traditional method that bring error to calculate. The radiative and conductive heat transfer model is solved by finite volume method combined with Monte Carlo method, and the db9 wavelet is used for wavelet decomposition. The research shows that the wavelet decomposition detail coefficients of the temperature field are mainly concentrated in the 7-9 wavelet frequency bands, while the wavelet detail coefficient in the 1-6 frequency bands is basically 0, This phenomenon is just the opposite of the random error, which could distinguish errors from parameters. The influence of physical parameters like thermal conductivity, extinction coefficient and scattering albedo on wavelet coefficients amplitude is the same as that of temperature field. The temperature thermal response of 10PPI aluminum foam under the 1300K was measured by the self-designed high temperature device, and its effective thermal conductivity and radiation properties are obtained. The thermal conductivity at high temperature increases significantly, and its extinction coefficient also increases linearly with temperature.