Tangential blade root neck conic
A root extending from a platform of an airfoil is disclosed. The root may include a first portion having a generally cylindrical shape, and a second portion extending from the first portion to the platform. The second portion may have a circumference larger than a circumference of the first portion.
1. An airfoil of a gas turbine engine having a platform and a root extending from the platform, the root comprising:
a first portion having a generally cylindrical shape;
a second portion extending from the first portion to the platform, the second portion having a circumference larger than a circumference of the first portion;
a fillet between the first portion and the second portion; and
an end portion having a circumference larger than the circumference of the first portion and extending from the first portion in a direction away from the platform, the end portion having a bearing surface which is in contact with a bearing surface of a groove of a disk,
wherein the first portion, the second portion, and the end portion are formed as one piece with the platform and the airfoil.
2. The airfoil of claim 1 , wherein the second portion increases in cross-sectional area from the first portion to the platform.
3. The airfoil of claim 1 , wherein the second portion has a generally conical shape.
4. The airfoil of claim 1 , wherein the second portion increases a frequency at which lower modes of the airfoil occur.
5. The airfoil of claim 1 , further comprising a third portion between the first portion and the second portion, the third portion having a generally arcuate shape.
6. The airfoil of claim 1 , further comprising a fourth portion between the platform and the second portion, the fourth portion having a generally arcuate shape.
7. The airfoil of claim 1 , wherein the root is shaped to fit within a groove of a disk, and wherein the circumference of the first portion is determined by an upper wall of the groove.
8. The airfoil of claim 1 , wherein the first portion and the second portion are aligned with a central axis of the airfoil.
9. A gas turbine engine, comprising:
a compressor section;
a combustor section downstream of the compressor section;
and a turbine section downstream of the combustor section, at least one of the compressor section and the turbine section having an airfoil including a platform,
and a root extending from the platform, the root including a cylindrical neck;
a segment gradually increasing in cross-sectional area from the cylindrical neck to the platform;
a first fillet between the segment and the cylindrical neck; and
an end portion having a circumference larger than a circumference of the cylindrical neck and extending from the cylindrical neck in a direction away from the platform, the end portion having a bearing surface which is in contact with a bearing surface of a groove of a disk,
wherein the cylindrical neck, the segment, and the end portion are formed as one piece with the platform and the airfoil.
10. The gas turbine engine of claim 9 , wherein the segment is generally conical in shape.
11. The gas turbine engine of claim 9 , wherein the root further includes a second fillet between the segment and the platform.
12. The gas turbine engine of claim 9 , wherein the segment increases a frequency at which lower airfoil modes occur.
13. The gas turbine engine of claim 9 , wherein the root is positioned within a disk of the at least one of the compressor section and the turbine section.
14. A method for designing an airfoil, comprising:
providing the airfoil with a platform and a root extending from an under side of the platform;
gradually increasing a cross-sectional area from a cylindrical neck of the root to the platform in a segment between the cylindrical neck and the platform;
providing a first fillet between the segment and the cylindrical neck; and
providing the root with an end portion having a circumference larger than a circumference of the cylindrical neck and extending from the cylindrical neck in a direction away from the platform, the end portion having a bearing surface which is in contact with a bearing surface of a groove of a disk,
wherein the cylindrical neck, the segment, and the end portion are formed as one piece with the platform and the airfoil.
15. The method of claim 14 , further comprising providing the segment with a generally conical shape.
16. The method of claim 14 , further comprising providing a second fillet between the segment and the platform.
17. The method of claim 14 , further comprising increasing a frequency at which lower airfoil modes occur through a shape of the segment.