Thermo-mechanical Redesign of a High-Pressure Turbine Nozzle Guide Vane

Abstract

The current paper presents an internal cooling redesign for a high-pressure turbine nozzle guide vane. The primary design goal is to achieve a longer creep life at constant cooling consumption, referred to as maintenance concept. The same design could be used in performance concept, permitting coolant flow reduction without affecting durability. To minimize manufacturing costs, the same wax tool (external geometry) as the original one has been used, and the only change is the introduction of new core geometry. The ability to retrofit existing units is another important constraint for this development. Consequently, the new design has a similar cooling structure with the same coolant feed and pressure side cut-back ejection as the original vane. Design steps, as well as necessary tools, are discussed in detail. A simplified approach is presented to roughly estimate thermal-induced stress for complex geometries based on the temperature linearization concept. The method is shown to be suitable for the preliminary design optimization level while significantly reducing design cycle time. For the detailed design, comprehensive CFD and FEM simulations are performed to evaluate temperature, stress, and cumulative creep damage distributions. Results indicate that the new design has considerably alleviated airfoil max metal temperature as well as cross-sectional temperature gradients. For the maintenance concept, a 65% longer operating life is estimated, and for the performance concept, more than 20% of coolant flow will be saved.