Optimization of a Low Heat Load Turbine Inlet Vane

Abstract

Abstract : Often there is a distinction between the design of turbomachinery airfoils for aerodynamic performance and durability. However, future aero-engine systems require ever increasing levels of turbine inlet temperature causing the durability and reliability of components to be an ever more important design concern. As a result, the need to incorporate heat transfer predictions into traditional aerodynamic design and optimization systems presents itself. Here, an effort to design an airfoil with both acceptable aerodynamics and minimized heat load is reported. First, a Reynolds-Averaged Navier-Stokes (RANS) flow solver was validated over different flow regimes as well as varying boundary conditions against extensive data available in literature. Next, a nominal turbine inlet vane was tested experimentally for unsteady heat load measurements in a linear cascade. The tests were performed in a reflected shock tunnel to validate the flow solver further at the current experimental conditions, and special attention was paid to leading edge and suction side heat-flux characteristics. The nominal airfoil geometry was then redesigned for minimum heat load by means of both design practice and two types of optimization algorithms. Finally, the new airfoil was tested experimentally and unsteady heat load trends were compared to design levels as well as the nominal vane counterpart. Results indicate an appreciable reduction in heat load relative to the original vane. Thus, it is a credible proposition to design turbine airfoils for aero-performance and durability concurrently.