Fluid-flow machine

1. A fluid-flow machine, comprising:

at least one rotor having a rotary element with a plurality of rotor blades arranged on the rotary element, and

a circumferential casing having a central axis and surrounding the rotor,

at least one of the circumferential casing or a component connected thereto having an internal annular space surface which radially outwardly delimits a flow duct of the fluid-flow machine,

the annular space surface having a structuring in at least one area adjacent the rotor having a circumferential asymmetry relative to the central axis, and

wherein the annular space surface includes at least one interruption section extending in a circumferential direction, the interruption section providing the circumferential asymmetry and being formed by a recess, the annular space surface having exactly one recess or the annular space surface having a plurality of recesses provided circumferentially asymmetrically in the annular space surface;

wherein an axial extent of the recess is larger than an entire axial extent of a blade row of the at least one rotor to extend both upstream and downstream of the entire axial extent of the blade row.

2. The fluid-flow machine of claim 1 , wherein the annular space surface is smooth along a circumference thereof not occupied by the interruption section.

3. The fluid-flow machine of claim 1 , wherein the annular space surface also includes at least one symmetrical structuring in the circumferential direction.

4. The fluid-flow machine of claim 1 , wherein the recess has at least one radius which differs from a radius of the annular space surface along a circumference thereof not occupied by the interruption section, with reference to the central axis.

5. The fluid-flow machine of claim 1 , wherein the annular space surface has exactly one recess.

6. The fluid-flow machine of claim 5 , wherein the annular space surface has a plurality of recesses, which are provided circumferentially asymmetrically in the annular space surface.

7. The fluid-flow machine of claim 5 , wherein the recess in a section in a plane perpendicular to the central axis has at least one of a bent or rectangular shape.

8. The fluid-flow machine of claim 1 , wherein the circumferential casing includes the annular space surface.

9. The fluid-flow machine of claim 1 , and further comprising a liner connected internally to the circumferential casing, the liner including the annular space surface.

10. The fluid-flow machine of claim 1 , wherein the annular space surface is provided in an area of a blade cascade of a rotor.

11. The fluid-flow machine of claim 10 , wherein the annular space surface is also provided in axial areas of at least one of the circumferential casing or a part connected thereto, the axial areas being located at least one of ahead of or behind an adjacent blade cascade.

12. The fluid-flow machine of claim 1 , wherein the fluid-flow machine is a compressor of a jet engine.

13. The fluid-flow machine of claim 1 , wherein the recess includes a plurality of circumferentially extending and same shaped parallel grooves.

14. The fluid-flow machine of claim 13 , wherein the recess has a constant axial length and a constant circumferential length.

15. A fluid-flow machine, comprising:

at least one rotor having a rotary element with a plurality of rotor blades arranged on the rotary element, and

a circumferential casing having a central axis and surrounding the rotor,

at least one of the circumferential casing or a component connected thereto having an internal annular surface which radially outwardly delimits a flow duct of the fluid-flow machine,

the annular surface adjacent the rotor having a circumferential asymmetry relative to the central axis by having a first circumferential section having a surface structuring and a second circumferential section having a substantially smooth surface, wherein the surface structuring includes at least one interruption section extending in a circumferential direction, the interruption section providing the circumferential asymmetry and being formed by a recess, the surface structuring having exactly one recess or the surface structuring having a plurality of recesses provided circumferentially asymmetrically in the annular surface;

wherein an axial extent of the recess is larger than an entire axial extent of a blade row of the at least one rotor to extend both upstream and downstream of the entire axial extent of the blade row.

16. The fluid-flow machine of claim 15 , wherein the surface structuring has exactly one recess.

17. The fluid-flow machine of claim 15 , wherein the surface structuring has a plurality of recesses, which are provided circumferentially asymmetrically in the annular space surface.

18. The fluid-flow machine of claim 15 , wherein the recess includes a plurality of circumferentially extending and same shaped parallel grooves.

19. The fluid-flow machine of claim 18 , wherein the recess has a constant axial length and a constant circumferential length.