12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
This study focuses on a high pressure turbine stage featuring a cavity above the rotor shroud. This cavity is purged by cooling air, and connected to the main gas path by an axisymmetric slot between the stator and the rotor. A 360° URANS simulation of this configuration has been per-formed. Flow structures generated by an aerodynamic instability are found in the slot between the annulus and the cavity. They form cells of hot gas ingestion alternating with zones of cooling air ejection, which rotate at a lower speed than the rotor. The effect of these structures on the flow through the turbine stage has been assessed, and compared to previously published results on a restricted computational domain which did not exhibit this instability. Similar interaction mechanisms occur, but their frequency differs because of the rotation of the structures in the slot.