Turbine blade tip/outer airseal/platform flow analysis

The interaction between the main passage flow through a high pressure turbine and the secondary flows due to leakage through the wheelspace rim seals is reviewed. Various experimental and analytical studies of these interactions are outlined and a numerical investigation of the interaction between the main passage flow and a wheelspace cavity seal flow is described. The numerical investigation uses a structured grid method to study the overall interaction between the turbine stage components and the wheelspace seal flow, and an unstructured grid method to resolve the detailed flow features within the geometrically complex cavity seal. The numerical results agree with various observations from experimental studies under similar flow conditions. As the flow rate through the rim cavity seal is increased, the ingestion of fluid from the main passage flow into the rim seal area decreases rapidly. A small amount of main flow gas is ingested into the rim seal area, even at high seal flow rates.