PURGE FLOWS IN TURBINE DISC CAVITIES AND RIM SEAL FLOWS

The turbine inlet temperature of a modern gas turbine engine is continuously increasing to achieve higher turbine efficiency. Turbine main flow with high temperature can be ingested into wheel-space or rotor-stator disc cavity. This hot gas ingestion phenomenon causes critical structural damage for turbine disc component. One driving force of the hot gas ingestion is the pressure asymmetry of the turbine main flow due to the potential effects of the stator vanes. In the high-pressure region, ingress of the turbine main flow into wheel-space occurs. Hot gas ingestion is prevented by supplying purge air from the high-pressure compressor (HPC) into the wheel-space and/or placing rim seals at the interface between the wheel space and main annulus.
The current research aim is to evaluate performance of various wheel space configurations including rim seals. Another research aim is main-purge flow interaction. Egressed purge flow from the wheel space interacts with the turbine main flow and generates extra losses. To measure sealing performance, CO2 tracer gas concentration is measured, and unsteady instrumentation is used to measure flow interactions.