Numerical Prediction Of Dangerous Regions In A 3D Turbine Blade With Multilayer-Structure TBCs By A Fluid-Solid Coupling Method

As a kind of temperature-resistance material have been widely applied in super high temperature components in aircraft engines. While cracking and flaking off of thermal barrier coatings(TBCs) lead to the immediate damage of the turbine blade, and further the whole engine, which seriously restrict its application. The high temperatures and stress concentrations act as the local sources of damage initiation and defects propagation in the form of cracks, therefore, in order to investigate the failure of TBCs, it is necessary to know the temperature distribution of blade. In this paper, a reasonable turbulence model has been selected to simulate the internal flow file from three kinds of the most frequently used turbulence models. A three-dimensional numerical model of a turbine blade with TBCs has been developed to investigate the temperature distribution and thermal-stress field by a fluid-solid coupling method. The research content and results are illustrated as follows:(1) A mathematical model contained fluid domain and solid domain and coupling interface was built in this paper. The external flow field and temperature field of solid domain are governed by compressible turbulent flow Navier-Stokes equations and solid thermal-conductivity equations, respectively. Continuous conditions was specified in the coupling interface.(2) Based on the coupling interface of MPCCI, a fluid-structure coupling scheme between FLUENT and ABAQUS was built, which the fluid domain was simulated by FLUENT, the solid domain include turbine blade and thermal barrier coatings analyzed by ABAQUS, the transfer of coupling variables was implemented by MPCCI. Based on this scheme, a FEM model contain turbine blade with multilayer-structure TBCs and its appropriate external flow file was built. The material parameters, boundary conditions and loading were defined according experiment dates. Finally, iterated the procedure after meshing.(3) This paper discusses the results of the established numerical model that applied RNG-ε 、 realizable-ε and SST-w turbulence model. The results showed that the temperature and pressure distribution of external flow file are similar, while at the stagnation point, there are large differences exist. Compared with experiment dates, the distribution of temperature and pressure performed by realizable- ε turbulence model exhibited the best agreement. Therefore, in this case, the conclusion that realizable-ε model has the best accuracy compared with the experimental data and predict the complex flow near the blade surface better can be obtained.(4) Based on the selection of turbulence models on the CHT simulation results, the temperature file and thermal stress file of a 3D turbine blade with multilayer-structure TBCs were obtained. The distribution of temperature is not homogeneous both thermal TBCs and turbine blade under really condition. The maximum temperature with a value of 1296 K occurred at the leading edge, the minimum value only 1089 K located at the suction side. TBCs performed a excellent heat insulation ability. In addition, it appears that temperature distribution in the coating thickness direction varies from region to region, ranging from 45 to 72 K, TBCs presents an excellent insulating effect and the heat insulation performance at the leading and trailing edges are relatively better than the suction and pressure sides. The stress level of TC is higher than BC, the maximum stress of TC with a value of 194 MPa, and the BC with a maximum value of 118 MPa, they both occurred at the blade root near leading edge, namely, TBCs may scale off at this region, especially the TC.