Blade for a flow machine
In a blade intended to be exposed to a gas flow at high speed during operation of a flow machine comprising the blade, the blade includes a front end designed to face towards the incoming gas flow and a rear end. The front end is provided with a concave area that is such that during operation a stagnation point for the incoming gas flow arises at a distance in front of an outer blade surface that defines the concave area and such that the outer blade surface is thereby at least partially protected from the incoming gas flow.
1. A blade intended to be exposed to a gas flow at high speed, during operation of a flow machine comprising the blade, the blade comprising a front end designed to face towards the incoming gas flow and a rear end, the front end being provided with a concave area that forms, during operation, a stagnation point for the incoming gas flow at a distance in front of an outer blade surface that defines the concave area so that the outer blade surface is thereby at least partially protected from the incoming gas flow, the blade comprising a first and second side wall defining a central cavity, and wherein a joint that joins together the first and second side walls is positioned within the concave area and there is no flow communication between the concave area and the central cavity, the concave area extends from a root of the blade to a top of the blade, and the concave area is more pronounced at at least one of the root of the blade and the top of the blade than at a region between the root of the blade and the top of the blade.
2. The blade as claimed in claim 1 , wherein the concave area is arranged substantially centrally in the front end relative to first and second outer walls that define the blade in a transverse direction.
3. The blade as claimed in claim 1 , wherein a width of the concave area in a transverse direction of the blade is at least 10% of a width of the front end.
4. The blade as claimed in claim 1 , wherein a depth of the concave area is at least 10% of a width of the front end.
5. The blade as claimed in claim 1 , wherein the side walls are made of metal or composite material.
6. An aircraft engine component in an aircraft engine provided with a gas turbine comprising the blade as claimed in claim 1 wherein, in operation, the blade is subjected to a flow of fluid that passes the blade at high speed in a direction from the front end towards its rear end.
7. The aircraft engine component as set forth in claim 6 , wherein the component is a structurally-supporting element.
8. The aircraft engine component as set forth in claim 6 , wherein the component is a guide in a gas turbine stator.
9. A flow machine component comprising a plurality of blades extending in a radial direction from an element to which they are attached, which blades are arranged a distance apart around the circumference of the component, wherein at least one of the blades is a blade as claimed in claim 1 .
10. A gas turbine, comprising at least one blade as claimed in claim 1 .
11. An aircraft engine, comprising at least one blade as claimed in claim 1 .
12. The blade as claimed in claim 1 , wherein the side walls are made of metal and the joint is a welded joint.
13. The blade as claimed in claim 1 , wherein the joint comprises a weld that protrudes from a surface surrounding the weld.
14. The blade as claimed in claim 1 , wherein the concave area extends along all of a part of the blade subjected to fluid flow during operation.
15. A blade intended to be exposed to a gas flow at high speed, during operation of a flow machine comprising the blade, the blade comprising a front end designed to face towards the incoming gas flow and a rear end, the front end being provided with a concave area that forms, during operation, a stagnation point for the incoming gas flow at a distance in front of an outer blade surface that defines the concave area so that the outer blade surface is thereby at least partially protected from the incoming gas flow, the blade comprising a first and second side wall defining a central cavity, and wherein a joint that joins together the first and second side walls is positioned within the concave area and there is no flow communication between the concave area and the central cavity, the front end within the concave area is at least partially formed by wall parts, and at least one duct is arranged through at least one of the wall parts that form the front end within the concave area and the duct is at a non-zero distance from an outermost part of the front end.
16. The blade as claimed in claim 15 , wherein the at least one duct opens out at an acute angle backwards in relation to an outer surface of the at least one of the wall parts through which the duct is arranged.
17. A section for a flow machine component, which section comprises a first and a second blade half, which are arranged a distance apart and are intended to form part of two adjacent blades in the component, which between them define a gas duct, with each of the blade halves comprising a front end designed to face towards an incoming gas flow during operation of a flow machine that comprises the component, and a rear end, wherein the front end of each of the blade halves is provided with a concave area that is such that a blade in the component formed by two blade halves from adjacent sections forms a blade concave area that gives rise to a stagnation point for the incoming gas flow at a distance in front of an outer blade surface that defines the blade concave area and the outer blade surface is thereby at least partially protected from the incoming gas flow, the blade in the component formed by two blade halves from adjacent sections having a central cavity and there being no flow communication between the blade concave area and the central cavity, wherein the concave area extends from a root of the blade to a top of the blade, and the concave area is more pronounced at at least one of the root of the blade and the top of the blade than at a region between the root of the blade and the top of the blade.
18. A flow machine component comprising a plurality of sections that are joined together in the direction of the circumference and form a circular structure, wherein at least two of the the sections each form a section as claimed in claim 17 .
19. A gas turbine, comprising at least one component as claimed in claim 18 .
20. An aircraft engine, comprising at least one component as claimed in claim 18 .
21. The section as set forth in claim 17 , wherein the blade in the component formed by two blade halves from adjacent sections comprises a welded joint that protrudes from a surface surrounding the weld.
22. The section as set forth in claim 17 , wherein the blade concave area extends along all of a part of the blade subjected to fluid flow during operation.