Optimization design of turbine blade cooling structure based on conjugate heat transfer

Conjugate heat transfer (CHT) has been widely used in the analysis on flow field and heat transfer of turbine blades. In this paper, a baseline design of turbine rotor blade is selected. By improving the arrangement of film holes, turning cylindrical holes into laid back fan-shaped holes in the pressure surface (PS) and suction surface (SS), and reducing the radially inclined angle of film holes on the leading edge (LE), an optimized design (OPT) is created. Grid independence validation is conducted by comparing the pressure and temperature distributions adopting three different numbers of grids. In order to select a suitable turbulence model, experiment is performed and its values are compared with the calculation results of three different turbulence models. The distributions of static pressure, static temperature, overall cooling effectiveness and streamlines of cooling flow are compared between the OPT and baseline design by the numerical calculation results of CHT. Furthermore, the adiabatic film cooling effectiveness is calculated and the cooling performances between cylindrical holes and laid-back fan-shaped holes are compared. At last, the flow and heat transfer mechanisms are analyzed and the forming causes of low or high temperature regions on the blade are explained. Calculation results show that compared with the baseline design, the area average temperature drops by 2.6% on the PS and by 3.7% on the SS. The area average overall cooling effectiveness increases by 9.3% on the PS and by 14.1% on the SS. The cooling performances are promoted greatly on the PS and SS but change little on the LE and TE. Obviously, the improvements are successful.