Rotor element and method for producing the rotor element

1. An axial flow rotor element, comprising:

a rotor element body having mechanical frequencies including a first set of mechanical natural frequencies that interact; and

at least one irregularity on the rotor element body, the irregularity being positioned to alter the first set of mechanical natural frequencies so as to disturb interaction between the first set of mechanical natural frequencies and prevent aeroelastic instability caused by interaction between the first set of mechanical frequencies through their dynamical connection with a passing gas flow.

2. Rotor element according to claim 1 , wherein the irregularity is formed so that different sectors in a circumferential direction of the rotor element have different mass and/or rigidity.

3. Rotor element according to claim 1 , wherein the irregularity is formed so that different sectors in a circumferential direction of the rotor element have different material thickness and/or composition and/or configuration.

4. Rotor element according to claim 1 , wherein the irregularity is formed so that at least one of a plurality of sectors in a circumferential direction of the rotor element has a cavity.

5. Rotor element according to claim 1 , wherein the irregularity is formed so that at least one of a plurality of sectors in a circumferential direction of the rotor element has an opening extending throughout the rotor element.

6. Rotor element according, to claim 1 , Wherein at the irregularity is formed so that at least one of a plurality of sectors in a circumferential direction of the rotor element has a projection.

7. Rotor element according to claim 1 , wherein the rotor element comprises at least one annular portion extending around a central rotor axis and projecting from the rotor element, and that the irregularity is formed so that the annular portion is circumferentially interrupted by at least one cavity.

8. Rotor element according to claim 1 , wherein the rotor element comprises a plurality of circumferentially spaced radial spokes.

9. Rotor element according to claim 8 , wherein the irregularity is formed so that the spokes are irregularly spaced in the circumferential direction.

10. Rotor element according to claim 1 , wherein a rotor element portion comprising the irregularity is rotationally rigidly arranged with regard to a rotor element body.

11. Rotor element according to claim 1 , wherein a rotor element, portion comprising the irregularity is formed in a one-piece unit with the rotor element.

12. Rotor element according to claim 1 , wherein the rotor element is disk-shaped.

13. Rotor element according to claim 1 , wherein the rotor element has a circular-cylindrical shape with a substantial extension in an axial direction.

14. Rotor element according to claim 1 , wherein the rotor element comprises a plurality of circumferentially spaced rotor blades.

15. Rotor element according to claim 14 , wherein the irregularity is positioned radially inside of the blades.

16. Rotor element according to claim 1 , wherein the irregularity is positioned in a rotor element body of the rotor element.

17. Rotor element according to claim 1 , wherein the rotor element is adapted for a high-speed application.

18. A method for producing a rotor element, comprising

forming a rotor element body having mechanical frequencies including a first set of mechanical natural frequencies that interact; and,

positioning at least one irregularity on the rotor element body to alter the first set of mechanical natural frequencies so as to disturb interaction between the first set of mechanical natural frequencies and prevent aeroelastic instability caused by interaction between the first set of mechanical frequencies through their dynamical connection with a passing gas flow.

19. A method according to claim 18 , comprising forming the irregularity by forming different sectors in a circumferential direction of the rotor element with different mass and/or rigidity.

20. A method according to claim 18 , comprising forming the irregularity by forming different sectors in a circumferential direction of the rotor element with different material thickness and/or composition and/or configuration.

21. A method according to claim 18 , comprising forming a rotor element portion comprising the irregularity so that it is rotationally rigidly arranged with regard to the rotor element body.

22. A method according to claim 18 , comprising forming a rotor element portion comprising the irregularity so that it is formed in a one-piece unit with the rotor element.

23. A method according to claim 18 , comprising forming, the rotor element with an excess of material in at least one sector in a circumferential direction of the rotor element in a first step and removing part of the excess of material by machining in a second step.

24. A method according to claim 23 , comprising forming the rotor element by turning a work piece in the first step.

25. A method according to claim 23 , comprising milling or grinding off the excess material in the second step.

26. A method according to claim 18 , comprising forming the rotor element with at least one annular portion extending around a central rotor axis and projecting from the rotor element.

27. A method according to claim 26 , comprising removing material from the annular portion at least one sector and thereby circumferentially interrupting the annular portion by at least one cavity.

28. A method according to claim 18 , comprising forming the rotor element in a first step and adding material in at least one of a plurality of sectors in its circumferential direction in a second step.

29. A method according to claim 28 , comprising adding the material by metal deposition in the second step.

30. A method according to claim 28 , comprising adding the material by spraying the material in plasma layers in the second step.