Influence of Opposing Dilution Jets on Effusion Cooling

Abstract

The gas turbine combustion process reaches gas temperatures that exceed the melting temperature of the combustor liner materials. Cooling the liner is critical to combustor durability and is often accomplished with double-walled liners that contain both impingement and effusion holes. The liner cooling is complicated with the interruption of the effusion cooling by large dilution jets that facilitate the combustion process. Given the presence of the dilution jets, it is important to understand the effect that the dilution jet has on the opposing wall in respect to the effusion film. This research includes measurements of the local static pressure distribution for a range of dilution jet momentum flux ratios to investigate the impact that the opposing dilution jet has on the effusion film. The interactions with the effusion cooling were also evaluated by measuring the overall cooling effectiveness across the panel. Measurements show that the opposing dilution jets did impact the liner at dilution jet momentum flux ratios that were greater than 20. The impacts at high momentum flux ratios were indicated through increased local static pressures measured on the surface of the combustor liner. Furthermore, the dilution touchdown decreased the overall cooling effectiveness of the effusion cooling. Results also indicated that the opposing dilution jets changed position on the liner as the dilution jet momentum flux ratio changes.