Optimization of stator and rotor blades using adjoint method in an axial turbine

Axial turbines are used to convert the energy of the high-energy gas coming out of the combustion chamber into mechanical energy by the stator and rotor blades and to transfer the power generated by this movement to the compressor shaft in gas turbine engines. Therefore, stator and rotor blade profiles significantly affect the efficiency of turbines. In this study, the 1.5-stage axial Aachen Turbine in the literature was taken as a reference, and it was aimed to optimize the 2D rotor-stator blades. Numerical studies were performed with the multi-purpose Ansys Fluent flow solver. First off, a 2D flow field was created using the reference geometry, then the appropriate mesh and flow problem were defined. In numerical studies, ideal gas assumption, compressible flow, steady-state flow conditions and k-ω SST turbulence model were used. Numerical study results were compared with the experimental data to validation work was carried out. In the first step of the optimization studies, the stator blade was optimized, and then the results were compared by performing it with different improvements ratios. In the second step, the rotor blade was optimized, and then the results were compared by performing it with different improvement ratios. The improvement results were evaluated by considering the pressure difference and entropy generation. As a result of this evaluation, profile improvement for the stator blade was limited to 7%, and 4% for rotor blade. Numerical analyzes were repeated using the optimized profiles, and it was seen that stage efficiency increased.