Steam-cooled gas turbine bucker for reduced tip leakage loss
AssigneeGeneral Electric Company
InventorsGary Michael Itzel, Philip Lynn Andrew
Life of this patent
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Abstract
A bucket for a steam turbine includes an airfoil portion having a radially outer tip, the radially outer tip having a thermal barrier coating applied thereto, and wherein the thermal barrier coating is resurfaced to form at least one ridge along the radially outer tip.
Claims10
A stage-one, steam-cooled bucket for a steam turbine comprising an airfoil portion incorporating a closed-loop steam cooling circuit and having a radially outer tip cap secured thereto, said radially outer tip cap covered with a thermal barrier coating, and wherein said thermal barrier coating is provided with a cavity defined by an area of reduced coating thickness in said thermal barrier coating extending along at least a center portion of said radially outer tip cap, wherein said cavity forms a ridge along only said suction side of said airfoil portion.
A stage-one, steam-cooled bucket for a steam turbine comprising an airfoil portion incorporating a closed-loop steam cooling circuit and having a radially outer tip cap secured thereto, said radially outer tip cap covered with a thermal barrier coating, and wherein said thermal barrier coating is provided with a cavity defined by an area of reduced coating thickness in said thermal barrier coating extending along at least a center portion of said radially outer tip cap,
- wherein said cavity forms a ridge along only said pressure side of said airfoil portion.
A method of reducing tip leakage loss at a radially outer tip of a stage-one, steam-cooled turbine bucket comprising:
- (a) providing a stage-one, steam turbine bucket incorporating a closed-loop steam cooling circuit;
- (b) covering substantially entirely the radially outer tip of the bucket with a thermal barrier coating of first predetermined thickness;
- (c) resurfacing by machining or grinding all of the thermal barrier coating to reduce said first predetermined thickness and including resurfacing the thermal barrier coating in selected portions of said thermal barrier coating to thereby define a ridge in said coating, extending along only a pressure side of said bucket and along substantially the entire length of said radially outer tip.
A method of reducing tip leakage loss at a radially outer tip of a stage-one, steam-cooled turbine bucket comprising:
- (a) providing a stage-one, steam turbine bucket incorporating a closed-loop steam cooling circuit;
- (b) covering substantially entirely the radially outer tip of the bucket with a thermal barrier coating of first predetermined thickness;
- (c) resurfacing by machining or grinding all of the thermal barrier coating to reduce said first predetermined thickness and including resurfacing the thermal barrier coating in selected portions of said thermal barrier coating to thereby define a ridge in said coating, extending along substantially the entire length of said radially outer tip;
- and
- wherein said ridge extends along only a suction side of said bucket.
Dependencies are inferred from the claim text.