Potential of a Nozzle Guide Vane Cooling Concept Adapted to Circumferential Temperature Variations

Abstract

This study explores the relationship between spatial turbine inlet temperature variations and potential cooling air savings by optimizing nozzle guide vane (NGV) cooling configurations. As turbine inlet temperatures increase to enhance thermal efficiency, the need for effective cooling systems that minimize cooling air consumption becomes critical. Currently, NGV cooling configurations are designed based on the peak gas temperature occurring within the hot streak downstream the center of the burner. This leads to excessive cooling in regions downstream of lower temperature zones, thereby reducing turbine efficiency. By considering the radial and circumferential temperature distribution at the combustor outlet, the study demonstrates that adapting NGV cooling configurations to these variations can significantly reduce total cooling air consumption. Computational fluid dynamics (CFD) simulations are used to prepare the boundary conditions required for the cooling design for burner-NGV ratios of 1:2, 2:5 and 1:5. A semi-empirical cooling design tool is used to develop a state-of-the-art cooling configuration for a high-pressure turbine NGV in each case with subsequent cooling configurations tailored to the thermal load between hot streaks. The alternating cooling designs in the circumferential direction reduce the required amount of coolant by 9.1 % to 13.6 %. These results provide valuable insight for turbine designers, allowing them to optimize cooling strategies by balancing the potential air savings with the associated design complexity, ultimately improving turbine efficiency.