Turbine rotor non-metallic blade attachment
In an engine disk and blade combination, the metallic disk has a plurality of first blade attachment slots and a plurality of second blade attachment slots circumferentially interspersed with each other. There is a circumferential array of a plurality of first blades. Each first blade has an airfoil and an attachment root. The attachment roots are respectively received in associated said first attachment slots. There is a circumferential array of second blades. Each second blade has an airfoil and an attachment root. The attachment roots are respectively received in associated said second slots. The first blades and second blades are non-metallic. The first blades are radially longer than the second blades. The first slots are radially deeper than the second slots.
1. An engine disk and blade combination comprising:
a metallic disk having: a plurality of first blade attachment slots; and a plurality of second blade attachment slots, circumferentially interspersed with the first attachment slots;
a circumferential array of first blades, each first blade comprising: an airfoil; and an attachment root, the attachment root received in an associated respective said first attachment slot; and
a circumferential array of second blades, each second blade comprising: an airfoil; and an attachment root, the attachment root received in an associated respective said second attachment slot,
wherein:
the first blades and second blades are non-metallic;
the first blades are radially longer than the second blades;
the first slots are radially deeper than the second slots;
tips of the first blades are at like radial positions to tips of the second blades at a given axial position;
the first blades have a characteristic chord;
the second blades have a characteristic chord, less than the characteristic chord of the first blades;
the first slots have a first circumferential span; and
the second slots have a second circumferential span, less than the first circumferential span.
2. The combination of claim 1 wherein:
the first blade attachment slots and second blade attachment slots are alternatingly interspersed in the absence of additional interspersed slots.
3. The combination of claim 1 wherein:
there are equal numbers of the first blade attachment slots and second blade attachment slots interspersed one after the other.
4. The combination of claim 1 wherein:
the combination is a turbine stage.
5. The engine of claim 1 wherein:
the disk comprises a nickel-based superalloy; and
the first blades and second blades comprise a structural ceramic or ceramic matrix composite.
6. The combination of claim 1 wherein:
the first blades have a characteristic tip longitudinal span; and
the second blades have a characteristic tip longitudinal span, less than the characteristic tip longitudinal span of the first blades.
7. The combination of claim 1 wherein:
the first blades have a characteristic leading edge axial position; and
the second blades have a characteristic leading edge axial position, aft of the characteristic leading edge axial position of the first blades.
8. The combination of claim 1 wherein:
the first slots have a first mass and a first center of gravity position; and
the second slots have a second mass, less than the first mass and a second center of gravity position radially outboard of the first center of gravity position.
9. The combination of claim 1 wherein:
the second blades have centers of gravity radially outboard of centers of gravity of the first blades.
10. The combination of claim 1 wherein:
the first blades have platforms of equal circumferential span to platforms of the second blades.
11. The combination of claim 1 wherein:
the first blades have platforms of circumferentially greater span than platforms of the second blades.
12. An engine disk and blade combination comprising:
a metallic disk having: a plurality of first blade attachment slots; and a plurality of second blade attachment slots, circumferentially interspersed with the first attachment slots;
a circumferential array of first blades, each first blade comprising: an airfoil; and an attachment root, the attachment root received in an associated respective said first attachment slot; and
a circumferential array of second blades, each second blade comprising: an airfoil; and an attachment root, the attachment root received in an associated respective said second attachment slot,
wherein:
the first blades and second blades are non-metallic;
the first blades are radially longer than the second blades;
the first slots are radially deeper than the second slots;
tips of the first blades are at like radial positions to tips of the second blades at a given axial position;
the first blades have a characteristic chord;
the second blades have a characteristic chord, less than the characteristic chord of the first blades; and
the first blades have platforms of circumferentially greater span than platforms of the second blades.