Rolls-royce Corporation

John L Winter

Harry Henshaw

Jonathan R Lilleker

In order to facilitate efficient use of high pressure cooling air in a turbine rotor blade its aerofoil has a triple-pass convoluted cooling air duct in its leading edge region, and a triple-pass convoluted cooling air duct in its mid-chord region, both of them being fed from a common high pressure inlet in the root of the blade. The trailing edge region has a single-pass duct fed by low pressure cooling air from an inlet located just under the blade platform. The shroud of the blade also has cooling air passages and these are fed from the ends of respective ones of the ducts. Air from the ducts also exits through rows of film cooling holes to film cool the concave flank of the aerofoil and through a row of holes in its trailing edge to remove heat from the thinner metal section in that area.

Cooling of turbine blades

The cooling air from the nozzle guide vanes of a gas turbine engine is discharged from one or both platforms to discourage leakage flow between rotating and static components of the engine. In the case of the outboard platform the cooling air is discharged towards the engine casing to flow through the clearance between the shroud of the engine casing and the shroud of the turbine blades. This arrangement reduces the leakage flow of gas from the main gas stream and assists in reducing casing temperatures.

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Derby, United Kingdom

John L Winter