Double Wall Effusion Turbine Cooling: The impact of deterministic unsteadiness and transients.

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This project will seek to determine the impact of flow unsteadiness that emanates from wake passing and changes in the flow field experienced by the rotor blades positioned downstream of the nozzle guide vanes. The combustor can also develop significant turbulence and flow unsteadiness. The work will evaluate the impact of unsteadiness on the effectiveness of the active cooling system to be implemented in the double wall effusion cooled turbine blade. The research will use both computational fluid dynamics and low speed experiments in a large-scale wind tunnel. This research will explore the use of novel techniques for generating unsteadiness including fluidic devices as well squirrel cage or rotating bar apparatus that previous studies have employed. The aim is to better represent the necessary bandwidth to study this phenomenon and will reduce the experimental complexity involved in the aforementioned apparatus. This research will provide unique data on the effects of ingestion on film cooling, as well as the threshold necessary in the double wall system to prevent ingestion. The impact of this research will be to enable to design of a high-pressure turbine blade with significant reduction in coolant supply. Coolant, whilst necessary, is a source of loss and the reduction of its injection into the working fluid of a gas turbine engine can have dramatic effects on the efficiency and power of the machine. An understanding of the likely response of the double wall system to engine representative unsteadiness is therefore pertinent to the assessment of double wall performance.