Compressor aerofoil

1. A compressor aerofoil for a turbine engine, the compressor aerofoil comprising:

a root portion spaced apart from a tip portion by a main body portion;

wherein the main body portion is defined by: a suction surface wall having a suction surface, a pressure surface wall having a pressure surface, whereby the suction surface wall and the pressure surface wall meet at a leading edge and a trailing edge,

wherein the tip portion comprises a shoulder provided on the pressure surface wall between the leading edge and the trailing edge; a tip wall which extends from the leading edge to the trailing edge; a transition region of the pressure surface wall which tapers from the shoulder in a direction towards the tip wall,

wherein the tip wall comprises a squealer defined by a first tip wall region which extends from the trailing edge to a winglet defined by a second tip wall region which increases in width relative to the first tip wall region to a tip wall widest point (A-A), and then reduces in width towards the leading edge

wherein a distance between the pressure surface and the suction surface of the main body along the extent of the squealer is wbB,

wherein a squealer width w1B has a value of at least 0.1 wbB but no more than 0.2 wbB.

2. The compressor aerofoil as claimed in claim 1 ,

wherein the first tip wall region which defines the squealer has a substantially constant width w1B along its extent.

3. The compressor aerofoil as claimed in claim 1 ,

wherein a chord line from the leading edge to the trailing edge has a length L; and wherein the winglet extends from the leading edge towards the trailing edge by a distance L1, where L1 has a value of at least 0.25 L but no more than 0.65 L.

4. The compressor aerofoil as claimed in claim 1 ,

wherein the pressure surface and the suction surface are spaced apart at a first section of the compressor aerofoil by a distance wbA and wherein the pressure surface and the suction surface are spaced apart at a second section of the compressor aerofoil by the distance wbB, wherein the first section is along the main body widest point (A-A), and wherein a second section (B-B) is along the squealer; and

wherein the distance wbA at the first section of the aerofoil decreases in value between the main body wides point (A-B) and the leading edge; and

wherein the distance wbB at the second section of the aerofoil decreases in value between the main body widest point (A-A) and the trailing edge.

5. A compressor rotor assembly for a turbine engine, the compressor rotor assembly comprising:

a casing, and

a compressor aerofoil as claimed in claim 1 ,

wherein the casing and the compressor aerofoil define a tip gap hg defined between the tip surface and the casing.

6. A compressor aerofoil for a turbine engine, the compressor aerofoil comprising:

a root portion spaced apart from a tip portion by a main body portion;

wherein the main body portion is defined by: a suction surface wall having a suction surface, a pressure surface wall having a pressure surface, whereby the suction surface wall and the pressure surface wall meet at a leading edge and a trailing edge,

wherein the tip portion comprises a shoulder provided on the pressure surface wall between the leading edge and the trailing edge; a tip wall which extends from the leading edge to the trailing edge; a transition region of the pressure surface wall which tapers from the shoulder in a direction towards the tip wall,

wherein the tip wall comprises a squealer defined by a first tip wall region which extends from the trailing edge to a winglet defined by a second tip wall region which increases in width relative to the first tip wall region to a tip wall widest point (A-A), and then reduces in width towards the leading edge,

wherein a chord line from the leading edge to the trailing edge has a length L; and wherein the winglet extends from the leading edge towards the trailing edge by a distance L1, where L1 has a value of at least 0.25 L but no more than 0.65 L,

wherein a widest point (A-A) of the winglet is at a distance of L2 from the leading edge, where L2 has a value of at least 0.4 L1 but no more than 0.6 L1.

7. A compressor aerofoil for a turbine engine, the compressor aerofoil comprising:

a root portion spaced apart from a tip portion by a main body portion;

wherein the main body portion is defined by: a suction surface wall having a suction surface, a pressure surface wall having a pressure surface, whereby the suction surface wall and the pressure surface wall meet at a leading edge and a trailing edge,

wherein the tip portion comprises a shoulder provided on the pressure surface wall between the leading edge and the trailing edge; a tip wall which extends from the leading edge to the trailing edge; a transition region of the pressure surface wall which tapers from the shoulder in a direction towards the tip wall,

wherein the tip wall comprises a squealer defined by a first tip wall region which extends from the trailing edge to a winglet defined by a second tip wall region which increases in width relative to the first tip wall region to a tip wall widest point (A-A), and then reduces in width towards the leading edge,

wherein along a length of the winglet, the winglet is narrower than a distance wbA between the pressure surface and the suction surface in a corresponding region of the winglet.

8. A compressor aerofoil for a turbine engine, the compressor aerofoil comprising:

a root portion spaced apart from a tip portion by a main body portion;

wherein the main body portion is defined by: a suction surface wall having a suction surface, a pressure surface wall having a pressure surface, whereby the suction surface wall and the pressure surface wall meet at a leading edge and a trailing edge,

wherein the tip portion comprises a shoulder provided on the pressure surface wall between the leading edge and the trailing edge; a tip wall which extends from the leading edge to the trailing edge; a transition region of the pressure surface wall which tapers from the shoulder in a direction towards the tip wall,

wherein the tip wall comprises a squealer defined by a first tip wall region which extends from the trailing edge to a winglet defined by a second tip wall region which increases in width relative to the first tip wall region to a tip wall widest point (A-A), and then reduces in width towards the leading edge,

wherein along a length of the winglet, the winglet is recessed beneath the pressure surface.

9. A compressor aerofoil for a turbine engine, the compressor aerofoil comprising:

a root portion spaced apart from a tip portion by a main body portion;

wherein the main body portion is defined by: a suction surface wall having a suction surface, a pressure surface wall having a pressure surface, whereby the suction surface wall and the pressure surface wall meet at a leading edge and a trailing edge,

wherein the tip portion comprises a shoulder provided on the pressure surface wall between the leading edge and the trailing edge; a tip wall which extends from the leading edge to the trailing edge; a transition region of the pressure surface wall which tapers from the shoulder in a direction towards the tip wall,

wherein the tip wall comprises a squealer defined by a first tip wall region which extends from the trailing edge to a winglet defined by a second tip wall region which increases in width relative to the first tip wall region to a tip wall widest point (A-A), and then reduces in width towards the leading edge,

wherein along a length of the winglet, the winglet is narrower than a distance wbA between the pressure surface and the suction surface in a corresponding region of the winglet

wherein a widest point (A-A) of the winglet has width w3A of at least 0.8 wbA but no more than 0.95 wbA.

10. The compressor aerofoil as claimed in claim 9 ,

wherein the tip wall defines a tip surface which extends from the leading edge to the trailing edge;

wherein at the widest point (A-A) of the winglet the transition region of the pressure surface wall extends from the shoulder in a direction towards the suction surface, and

wherein at an inflexion point the transition region curves to extend in a direction away from the suction surface toward the tip surface.

11. The compressor aerofoil as claimed in claim 10 ,

wherein the tip portion further comprises an inflexion line defined by a change in curvature on the pressure surface;

the inflexion point being provided on the inflexion line; and the inflexion line extending between the leading edge and the trailing edge.

12. The compressor aerofoil as claimed in claim 11 ,

wherein the inflexion line is provided a distance h2A, h2B from the tip surface; and wherein the shoulder is provided a distance h1A, h1B from the tip surface;

where distance h1A, h1B has a value of at least 1.5 h2A but no more than 2.7 h2A.

13. A compressor rotor assembly for a turbine engine, the compressor rotor assembly comprising:

a casing, and

a compressor aerofoil as claimed in claim 12 ,

wherein the casing and the compressor aerofoil define a tip gap hg defined between the tip surface and the casing, and

wherein the distance h2A, h2B from the inflexion line to the tip surface has a value of at least 1.5 hg but no more than 3.5 hg.

14. The compressor aerofoil as claimed in claim 11 ,

wherein the inflexion line at the widest point of the winglet is provided a distance w2A from the suction surface;

wherein w2A has a value of at least 0.8 w3A but no more than 0.95 w3A.