Aero-thermal-elasticity-materials Optimization of Cooled Gas Turbine Blades: Part I

The first lecture in this two-lecture sequence provides background and general concepts. The second lecture provides practical examples. The objective of these two lectures is to provide a modular design optimization tool description that will take into account interaction of the hot gas flow-field, heat transfer in the blade material, internal coolant flow-field, stresses and deformations of the blades in a multi-stage axial gas turbine. These methodologies should result in a multi-disciplinary design optimization tool for the entire system (a multi-stage turbine) rather than a design method for an isolated component (a single turbomachinery blade). In order to make the entire design methodology computationally economical, the proposed method should utilize a combination of fast approximate models as well as highly accurate and detailed complete models for aerodynamics, heat transfer, and thermoelasticity. These calculations should be performed using parallel computing. The by-products of the optimization are shapes, optimized average surface roughness of the coolant passages, coolant bulk temperature variation, coolant bulk pressure variation and pressure losses in the coolant passages, and surface convective heat transfer coefficients in each of the coolant passages. The resulting benefits of using this general approach to design are: 1. maximized efficiency and minimum size and weight of the entire multi-stage cooled gas turbine at design and a wide range of off-design conditions, 2. multi-stage 3-D analysis and design capability instead of an isolated blade row capability, 3. simultaneous account of aerodynamics, heat transfer, and thermoelasticity instead of aerodynamics alone, 4. ability to specify geometric, flow-field, thermal, and stress/deformation constraints, 5. capability to analyze and optimize thermally coated and uncoated turbine blades, 6. maximized turbine inlet temperature for a fixed coolant mass flow rate, 7. minimized coolant mass flow rate for a fixed turbine inlet temperature, 8. optimized average surface roughness of the internal coolant flow passage walls, 9. reduced need for manufacturing of small holes for blade film cooling, 10. optimized networking of the small cooling channels for transpiration cooling, 11. optimized blade shapes in each blade row for minimum total pressure loss and maximum torque, 12. optimized thickness distribution of blade walls and interior struts of coolant flow passages inside each blade row, 13. optimized concentrations of alloying elements to be used for the blade material, 14. minimized overall design cycle time.