Turbine rotor dovetail structure with splines
AssigneePratt & Whitney Canada Corp.
InventorsFrancis Gemme, Othmane Leghzaouni, Robert Huszar, Daniel Lecuyer
Life of this patent
Estimating the term…
Abstract
A fir tree structure is provided and includes a part extending radially inwardly from a rotating part and having an inward taper. The part has a spline profile forming fixing lobes and necks, which are interleaved with the fixing lobes. The spline profile has constantly changing radii of curvature characterized in that the radii of curvature are relatively reduced in high stress locations and relatively increased in low stress locations.
Claims16
A fir tree structure, comprising:
- a part extending radially inwardly from a rotating part and having an inward taper,
- the part having a spline profile forming fixing lobes and necks, which are interleaved with the fixing lobes,
- the spline profile having constantly changing radii of curvature characterized in that the radii of curvature are relatively reduced in high stress locations and relatively increased in low stress locations,
- wherein:
- the fixing lobes comprise an inboard fixing lobe and an outboard fixing lobe, which is wider than the inboard fixing lobe,
- the fixing necks comprise an inboard fixing neck, which is inboard from the outboard fixing lobe, and an outboard fixing neck, which is outboard of the outboard fixing lobe and wider than the inboard fixing neck, and
- a plot of curvature along the inboard fixing neck exhibits a hump, a trough and an inflexion point between the hump and the trough that is closer to the hump.
A fir tree structure of a turbine blade, comprising:
- a blade part extending radially inwardly from the turbine blade and having an inward taper,
- the blade part having a spline profile forming blade fixing lobes and blade fixing necks, which are interleaved with the blade fixing lobes,
- the spline profile having constantly changing radii of curvature characterized in that the radii of curvature are relatively reduced in high stress locations and relatively increased in low stress locations,
- wherein:
- the blade fixing lobes comprise an inboard blade fixing lobe and an outboard blade fixing lobe, which is wider than the inboard blade fixing lobe,
- the blade fixing necks comprise an inboard blade fixing neck, which is inboard from the outboard blade fixing lobe, and an outboard blade fixing neck, which is outboard of the outboard blade fixing lobe and wider than the inboard blade fixing neck, and
- a plot of curvature along the inboard blade fixing neck exhibits a hump, a trough and an inflexion point between the hump and the trough that is closer to the hump.
A method of forming a fir tree structure of a turbine blade, the method comprising:
- providing a part extending radially inwardly from the turbine blade and having an inward taper;
- and
- forming the part to have a spline profile forming fixing lobes and fixing necks, which are interleaved with the fixing lobes,
- the forming of the part comprising:
- identifying high and low stress locations of the part;
- and
- designing the spline profile to have constantly changing radii of curvature characterized in that the radii of curvature are relatively reduced in the high stress locations and relatively increased in the low stress locations,
- wherein:
- the fixing lobes comprise an inboard fixing lobe and an outboard fixing lobe, which is wider than the inboard fixing lobe,
- the fixing necks comprise an inboard fixing neck, which is inboard from the outboard fixing lobe, and an outboard fixing neck, which is outboard of the outboard fixing lobe and wider than the inboard fixing neck, and
- a plot of curvature along the inboard fixing neck exhibits a hump, a trough and an inflexion point between the hump and the trough that is closer to the hump.
Dependencies are inferred from the claim text.