Analysis Of Force-thermal Coupling Response Of High-temperature Turbine Blades

As the core key component of the aero engine,turbine blades not only face the role of high-temperature gas during service,but also need to bear various forms of loads such as centrifugal force and aerodynamics,which puts forward a severe test for the safety and reliability of aero-engines.Since further increasing the thrust of the aero engine requires increasing the temperature before the turbine,in order to prevent the deterioration of the performance of related components and prolong the service life,the application of thermal barrier coating system to the surface of hot end components such as advanced gas turbines and aero-engines can effectively protect the substrate from high temperature transients and environmental influences,which is of great significance to the safe and stable operation of aero engines.In this paper,the elastoplastic finite element calculation of high-temperature blades is carried out under force-thermal coupling conditions,and the mechanical-thermal response mechanism of high-temperature blades is explored.Secondly,a thermal barrier coating is introduced for the high-temperature blade,the cooling process after the preparation of the thermal barrier coating blade is simulated,and the temperature field and stress state of the thermal barrier coating turbine blade under high temperature thermal shock and high speed are further simulated,and the stress mechanism of the difference in mechanical behavior between the blade substrate with thermal barrier coating and the blade without coating at high temperature is revealed.The results are as follows:(1)A three-dimensional finite element model of superalloy blades and thermal barrier coated turbine blades was established.Firstly,a simplified certain turbine blade geometric model is established,and the cooling channel structure and thermal barrier coating structure are added step by step,so as to establish a series of turbine blade finite element models from simplified certain blades,cooling channel blades,to more realistic simultaneous thermal barrier coating and cooling channel blades,so as to quantitatively analyze the influence of blade geometry and thermal barrier coating on their mechanical thermal behavior.(2)Based on the finite element method,the cooling process after the preparation of the thermal barrier coating of turbine blades was simulated and analyzed.By using thermal convection heat transfer to simulate the cooling stage of thermal barrier coating blades,the residual deformation and residual stress state of thermal barrier coating and blade substrate are obtained.The results show that the residual stress and residual deformation distribution generated by the thermal barrier coating after preparation are dominated by the cooling shrinkage and curvature changes of the blade,and the residual compressive stress value is within 0～200 MPa.(3)Based on the finite element method,the actual service process of superalloy blades and thermal barrier coated blades is simulated.According to the different working conditions of the aero-engine,the turbine blade failure analysis and research on centrifugal load,temperature load and coupling of the two loads are carried out in turn,and the stress distribution and evolution law of the turbine blade system are obtained,and it is found that the thermal barrier coating has the most obvious thermal barrier effect in the suction side during service,and the maximum blade temperature can be reduced by290 °C.Furthermore,a thermally grown oxide is introduced for the thermal barrier coated turbine blades,and its influence on the failure form of the thermal barrier coated turbine blades is discussed.