Automating the Design Process for 3D Turbine Blades

Abstract An automated design system has been developed by coupling a hybrid optimization technique to a quasi-3d aerodynamic analysis code for design of turbine blades. Using this technique, multiple quasi-3d surface airfoil sections of the turbine blade are optimized simultaneously and stacked radially to produce a smooth 3d turbine blade geometry, with optimal quasi-3d surface Mach number distributions. The airfoil geometry on quasi-3d m’/theta surfaces is modelled using 2d Bezier curves which ensure a reasonably smooth geometry and adequate flexibility for manipulating the blade shape. A combination of heuristic-search, and numerical optimization techniques is used in the design process. In each design iteration, the existing blade geometry is changed, the new geometry is analyzed using a Computational Fluid Dynamics (CFD) analysis code, and a numerical score of the blade quality is computed. The blade quality includes both the blade surface Mach number distribution and the smoothness of the radial stack of the blade. Both aerodynamic and mechanical constraints are imposed on the design to ensure that the optimized design meets feasibility requirements of both disciplines. The design system described herein is being used by engineers for production design of turbines at GE Steam Turbines. Short delivery schedules and custom designs required for each steam turbine unit manufactured make this technology a high priority in this business; at the same time GE Gas Turbine and GE Aircraft Engine also benefit from this development. The system has been demonstrated to turn an initial guess at the airfoil shape automatically derived by the aero design system into a full 3d turbine blade that meets aerodynamic, smooth radial stacking, and some mechanical requirements.