Thermal Performance Assessment of Helical Diverter Depth and Inlet Angle Configurations in Rotating Gas Turbine Blade Cooling Passages

Abstract Rising turbine-inlet temperatures demand more effective internal blade cooling to sustain efficiency and component life. This research investigates the thermohydraulic behavior of a rotating internal cooling channel with helical diverters (HD), focusing on two geometric factors: diverter depth (DD) and inlet angle (IA). The influence of these factors was investigated using RANS computational fluid dynamics simulations over a range of Reynolds numbers, from 20,000 to 50,000, with two rotation numbers (Ro = 0.25 and Ro = 0.5). Findings show that at moderate rotation number (Ro = 0.25), moderate diverter depths (80% of the channel length), and shallower inlet angles (11.25°-22.5°) significantly increase local and surface-averaged Nusselt numbers, with thermal performance factors (η) over 1.15, while pressure losses stay moderate. At a higher rotation number (Ro = 0.5), the thermal improvements diminish, especially with deeper diverters, which experience flow separation and Coriolis effects, primarily at the leading edge (LE). Shallow IA configurations give slight gains at the trailing edge (TE) but do not improve the overall system performance. These findings challenge the assumption that greater blockage or more complex geometry inherently enhance cooling performance under rotational conditions. This study emphasizes that passive geometric adjustments should be rotation-aware and tailored to specific locations. It suggests that future research should focus on additional geometric features, hybrid designs, and Coriolis effects to optimize the development of advanced turbine blade cooling systems.