Simulation of temperature field in a partially delaminated thermal barrier coating
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 78, Issue 2
Abstract
The problem of determining temperature in a thin partially delaminated thermal barrier coating is considered taking into account the convective heat exchange with the surrounding environment at the front and end surfaces of the coating and the imperfect thermal contact with the base, which is modeled by thermal resistance. In view of deterioration of heat exchange between the base and the coating in the separation region, thermal resistance in this region is assumed to be greater than thermal resistance in the regions of full adhesion. The heat-transfer coefficient at the front surface of the coating is coordinate-dependent. With the use of the propositions of heat conduction in thin elements of constructions, a model for describing temperature field in a partially delaminated coating, caused by the difference between the temperatures of the base and the surrounding environment, is proposed. Utilizing the method of variation of constants, an approach for reducing the heat conduction boundary value problem for the coating to a system of Fredholm integral equations of the second kind for the functions that are linear combinations of the integral characteristics of the coating temperature (the mean temperature and the temperature moment) and the temperature of the surrounding environment and the base is developed. A numerical scheme for solving the system of integral equations is constructed using the quadrature method. In particular, Simpson's quadrature formulae are utilized to evaluate the integrals, and the system of Fredholm integral equations of the second kind is reduced to a system of linear algebraic equations. The results of numerical analysis of temperature distribution at the front surface of the coating and at the interface between the coating and the base are given for the case of thermal insulation of the end surfaces and the case of convective heat exchange with the surrounding environment at them. The distributions of the mean temperature and the temperature moment are examined for various values of thermal resistance in the separation region. It is revealed that an increase in thermal resistance leads to a significant temperature perturbation at the front surface as well as at the interface between the coating and the base. However, the value of the temperature moment in the separation zone is slightly decreasing in comparison with the case when the delamination does not occur at the interface between the coating and the base.
Authors and Affiliations
Bogdan Khapko, Rostislav Martynyak
Keywords
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