A NEW TEST FACILITY FOR INVESTIGATING LEAF-SEAL CAVITY INGESTION AT COMBUSTOR-TURBINE INTERFACE

Spring-loaded leaf seals are commonly used to seal the hot gas path in gas turbine combustor - stage-1 nozzle interfaces. The leaf-seal cavity, created by the aft end of the combustor liner on one side and by the nozzle platform on the other, is susceptible to hot gas ingestion due to multiple factors including combustor swirl intensity, combustor and leaf-seal cavity geometry, and the proximity to the stage-1 nozzles. Ingested hot gases are diluted by cold compressor bleed air introduced inside the leaf-seal cavity. However, the aerodynamic and thermal environment is highly complex, and if the thermal design intent of the components near the interface is not met, combustor durability and sealing capability may be compromised. To provide insight into the leaf-seal cavity ingestion behavior and to investigate its sensitivity to various design parameters, a new atmospheric test rig was designed and commissioned. The test rig features a tri-sector annular swirl-stabilized combustor simulator, stage-1 nozzle guide vane mock-ups and a simplified leaf-seal cavity. The rig’s high modularity allows the geometry of the liners, the leaf seal, and the nozzles to be changed quickly and allows the main and cooling flows to be controlled separately. Optical access to the leaf-seal cavity, the aft panel of the inner liner, and the nozzle platform allows detailed analysis of the ingestion behavior and cooling effectiveness using pressure sensitive paint. Additional ingestion measurements are provided by gas concentration analysis at discrete points inside the leaf-seal cavity where optical access is poor. Results from a companion stress-blended eddy simulation study are presented which demonstrate the capability of scale-resolving computational fluid dynamics to accurately capture the ingestion behavior.