Optimization Methodology for the Design of Axial Turbine Flow Path and Blade Elements

Abstract

The main requirement of fighter aircraft aero gas turbine engine is to have high newlinethrust to weight ratio for better aircraft maneuverability and higher payload, low specific newlinefuel consumption for long aircraft range and low operating costs and long life for low life newlinecycle costs of the aircraft. Hence for fighter aircraft engines, turbines with high efficiency newlineand high turbine entry temperature with advanced cooling, materials and manufacturing newlineprocess can meet the above challenging demands. Turbine design has to meet the newlineconflicting demands of aerodynamic performance, thermal, structural and castability newlinerequirements. Hence optimization of turbine design in terms of aerodynamic performance, newlinelife and weight needs to be carried out. newlineIn the present research work, a methodology to optimize the turbine mean line newlinedesign taking into account aerodynamic performance, life and weight aspects using genetic newlinealgorithm is established. An optimization code based on genetic algorithm is integrated newlinewith mean-line code to carry out optimization for multiple input variables like flow newlinecoefficient, stage loading and exit swirl angle and objectives of turbine stage efficiency, newlinelife and weight. From the optimization, meridional flow-path, number of blades and vanes newlineand mean velocity triangles are obtained. newlineA meridional hub-to-tip controlled vortex design is carried out using stream line newlinecurvature code and obtained the hub, mean and tip velocity triangles. A profile generation newlinecode based on Bezier curves, to match the velocity triangles i.e. performance and with newlineflexibility to take care of thermal and structural requirements is developed. Hub, mean and newlinetip blade element profiles of stator and rotor have been generated using the developed code. newlineThe stator profiles are generated with aft-loading and the rotor blade profiles are generated newlinewith mid-loading by ensuring smooth flow acceleration and required flow deflection. The newlineblade element profiles are analyzed using a 2D time marching technique for different exit newlineMach number