Finite Element Simulation On Thermal Stress Of A Turbine Blade With Thermal Barrier Coatings Considering Cooling Channels

Thermal barrier coatings (TBCs) are the ceramic coatings with the insulating effect, itsthermal conductivity is generally lower than other materials which usually prepared on the outersurface of temperature alloy or metal to reduce the temperature of the protected alloy or metal, andalso greatly enhance the operating temperature of the substrate, thus improving the efficiency ofthe device or machine and extending its life. TBCs are widely used in many fields, especially inthe hot part of the aerospace aircraft, metallurgical industry, chemical industries and energyindustries. The object of this article is focused on the inside turbine blade thermal barrier coatingof the high-performance aero-engine. In actual use, the complex structure of turbine blades withTBCs and diversified using environment, making the stress evolution of the turbine blade withTBCs in actual service process to be the important and difficult issues of this research. So thisresearch is focus on the analysis of temperature changing and strain evolution of the turbine bladeTBCs in the thermal cycling considering cooling channel inside, and exploring the evolution of thestress, to determine the occurrence of easily damaged area. The main contents of this thesis are asfollows:Firstly, build the geometric model for the complex structure of the aero-engine turbine bladewith thermal barrier coatings considering the cooling tunnels. Build the aero-engine turbine bladewith thermal barrier coatings without considering the cooling channels, then, build the coolingtunnels’ geometry model. Merge them to form the final model. Define the property of matierials,load, boundary conditions and initial conditions. Calculate the field of temperature, calculate thefield of stress using the result of temperature, then.Secondly, analyse the result of the finite element simulation of temperature and stress fields.The temperature gradient distribution in the blade is very different at different positions, thebiggest temperature gradient is shared on the pressure surface. So, if only temperature distributionis considered, thermal barrier coatings on the pressure surface where the slimmest area compare tothe substrate have to bear higher temperature effect, but the protection is the best. Stress evolutionin ceramic layer can be found after the number of thermal cycles’ calculation. From the stress evolution after once heating, insulation and cooling cycle, we can found thata with the increase inthe number of thermal cycles, the stress in ceramic layer become smaller and smaller, and thenincrease to be the tensile stress after zero while tensile stress in most areas remain around a smallvalue, then will continue to increase with the increase of thermal cycles. When the tensile stressreaches a high value enough, YSZ would be damaged.Thirdly, The last work is the influence on thermal barrier coatings by diffenent coolingtunnels. Keeping the whole acreage and the thickness of TBCs same, we us the FEM to simulatethe temperature and stress fields. Then we found that different number of cooling tunnels made noeffect obviously when we don’t consider the cooling gas’ flow velocity and the change of heatexchange coefficient, on the other word, the temperature and stress fields are only concerned withthe thickness and the shape of the TBCs.This paper studied the finite element simulation of thermal barrier coatings consideringcooling channels and found out the stress evolution in layers, providing a guidance to improve theability to predict the life of the turbine blades and thermal barrier coatings heat cycle.