Method for reducing cooled turbine element stress and element made thereby
First Claim
1. A method of lowering a thermal stress at a trailing edge of an airfoil of a cooled turbine blade adjacent a platform of the blade, said method comprising the step of forming at least one cooling hole positioned upstream from the trailing edge of the airfoil and extending from an interior cooling air passage to an exterior surface of the airfoil for delivering cooling air to the exterior surface to cool the airfoil in an area of the exterior surface upstream from the trailing edge so that a thermal deflection of the airfoil more closely corresponds to a thermal deflection of the platform thereby lowering thermally induced stresses in the airfoil at the trailing edge thereof.
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Accused Products
Abstract
A cooled turbine element including an airfoil and a flowpath boundary member extending laterally from either an inboard end or an outboard end of the airfoil. The member has a flowpath face and an outside face which is cooler than said flowpath face creating a tendency for the member to deflect in a direction away from the flowpath face and causing a thermally induced tensile radial stress in a region of the trailing edge of the airfoil. The element has an interior cooling passage and at least one cooling hole extending from the interior cooling passage to an opening located in an area upstream from the stressed region of the trailing edge to cool the area so the airfoil thermally deflects to a shape corresponding to that of the boundary member thereby lowering the thermally induced tensile radial stress in the airfoil at the trailing edge thereof.
45 Citations
14 Claims
- 1. A method of lowering a thermal stress at a trailing edge of an airfoil of a cooled turbine blade adjacent a platform of the blade, said method comprising the step of forming at least one cooling hole positioned upstream from the trailing edge of the airfoil and extending from an interior cooling air passage to an exterior surface of the airfoil for delivering cooling air to the exterior surface to cool the airfoil in an area of the exterior surface upstream from the trailing edge so that a thermal deflection of the airfoil more closely corresponds to a thermal deflection of the platform thereby lowering thermally induced stresses in the airfoil at the trailing edge thereof.
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3. A cooled turbine element for use in a flowpath of a gas turbine engine comprising:
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an airfoil having a pressure side and a suction side opposite said pressure side, said pressure side and said suction side extending axially between a leading edge and a trailing edge opposite said leading edge and radially between an inboard end and an outboard end opposite said inboard end;
a flowpath boundary member extending laterally from at least one of said inboard end and said outboard end, said boundary member having a flowpath face and an outside face opposite the flowpath face, said outside face running cooler than said flowpath face during engine operation thereby creating a tendency for the member to deflect in a direction away from the flowpath face and causing a thermally induced tensile radial stress in a region of the trailing edge of the airfoil;
an interior cooling passage extending through the airfoil from a cooling air source for transporting cooling air through the airfoil; and
at least one cooling hole extending from the interior cooling passage to an opening located on one of said suction side and said pressure side in an area upstream from the stressed region of said trailing edge to cool said area to a temperature below that of the trailing edge so that the airfoil thermally deflects during engine operation to a shape corresponding to that of the flowpath boundary member thereby lowering the thermally induced tensile radial stress in the airfoil at the trailing edge thereof.
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Specification