Numerical Study Of The Thermal Insulation Of 8YSZ TBCs And Conjugate Heat Transfer Between Tbcs And Cooling Film

The output power and operation efficiency of gas turbine,as well as the weight ratio of aircraft engine can be optimized with the improvement of inlet temperature.Therefore,it is one of the key techniques for the development of turbine engines.However,the environment of the gas turbine blades becomes deteriorated with the improvement of the inlet temperature.This has been a key factor restricting the development of turbine engines.Thermal barrier coatings(TBCs)applied to gas turbine and cooling jet over the blade surface can efficiently protect the hot parts of gas turbine and improve the comprehensive performance of the blades,thus extend the cycle life of the turbine blades.Based on the four parameters random growth method and Matlab image recognition,two types of software programs were developed for the geometry reconstruction of thermal barrier coatings.Meanwhile,in order to analyze the relationship between the thermodynamic properties of coatings and the pores structure,analysis programs of lattice Boltzmann were compiled.Based on the M701 F gas turbine and the micro-structure of thermal barrier coatings,the thermal insulation of 3D thermal barrier coatings and the conjugate heat transfer between the thermal barrier coatings and the cooling film were analyzed in this paper through numerical program.Therefore,the effect of the microstructure of coatings on the flow and heat transfer was analyzed from microscopic perspective.The equivalent thermal conductivity and aerodynamic parameters with different porosity,pore size and length of elongated pore were calculated.The results showed that the equivalent thermal conductivity of columnar and layered coatings decreases and then increases with the improvement of temperature.The minimum thermal conductivity appears near the temperature of 700 C?.The equivalent thermal conductivity of the columnar coatings increases with the increase of pore diameters.When the porosity is 15% and pore diameter varies from 0.74?m to 5.46?m,the equivalent thermal conductivity is increased by 6.4%.But the layered coatings displayed opposite rules.The equivalent thermal conductivity is decreased by 5.3%.The thermal insulation performance reduced with the improved length of the elongated pores for columnar structure and within a certain growth probability range between 0.0002 and 0.2,the reduction was logarithmic.However,the opposite results were gained for layered coatings.For the conjugate heat transfer,there is weak flow in the interior perpendicular pores.Spatial variations in the velocity over the layered coatings are larger because of its rough surface.The spatial variations ratio can reach 2.5%.The fluctuation of the isothermal curve is severer for layered coatings compared with columnar coatings.The intensity of the conjugate heat transfer and the porosity of the thermal barrier coatings were positively correlated.The performance of the conjugate heat transfer between the layered coatings and the cooling film becomes better as improvement of the pore size and the length of the elongated pore.While the columnar coatings showed the opposite trend.