Multi-objective optimization of lean and sweep angles for stator and rotor blades of an axial turbine

Abstract

The axial turbine is one of the most challenging components of gas turbines for industrial and aerospace applications. With the ever-increasing requirement for high-aerodynamic performance blades, three-dimensional aerodynamic shape optimization is of great importance. In this research, the rear part of a gas turbine consisting of a one-stage axial turbine is optimized numerically. A useful optimization algorithm is presented to improve the efficiency and/or pressure ratio of the axial turbine with two different objective functions. The three-dimensional blade-shape optimization is employed to study the effects of the turbine stator and rotor lean and sweep angles on the turbine performance. The investigation is carried out at the turbine design speed. By coupling a verified computational fluid dynamics simulation code with the genetic algorithm, an automated design procedure is prepared. Geometry candidates for the optimization algorithm are generated by re-stacking of the two-dimensional airfoil sections. Three-dimensional, turbulent, and compressible flow field is numerically investigated via a Navier–Stokes solver to calculate various objective functions. Experimental results of the gas turbine are used for specifying the boundary conditions and validation of the simulation results. The proposed method results in 1.3% and 1.5% improvements in the turbine stage efficiency in design speed and reduced mass parameter at choke condition, respectively.