Gas turbine stator/rotor expansion stage having bumps arranged to locally increase static pressure

1. Gas turbine comprising:

an annular combustion chamber defined by an inner wall and an outer wall;

a stator airfoil row defined by an annular inner stator wall and an annular outer stator wall housing a plurality of stator airfoils, and at least a rotor airfoil row defined by an annular inner rotor wall and an annular outer rotor wall housing a plurality of rotor airfoils; and

a gap between at least one of the inner stator wall and the inner combustion chamber wall, and the outer stator wall and the outer combustion chamber wall, upstream of said stator airfoil row, wherein a border of at least one of the inner and outer stator wall facing the gap is axisymmetric, and a zone of the at least one inner and outer stator wall downstream of the gap and upstream of the stator airfoils is non-axisymmetric and defines bumps arranged to locally increase static pressure of a fluid flow passing through said stator airfoil row to increase uniformity of the static pressure.

2. Gas turbine according to claim 1 , wherein each bump is located in regions where the static pressure of the hot gas flow is lowest.

3. Gas turbine according to claim 2 , wherein said bumps are located along a circumference of at least one of the inner and outer stator walls.

4. Gas turbine according to claim 2 , wherein each bump faces a guide vane flow channel defined between two adjacent stator airfoils.

5. Gas turbine according to claim 4 , wherein each bump is closer to a suction side than to a pressure side of said two adjacent stator airfoils defining said guide vane flow channel.

6. Gas turbine according to claim 4 , wherein each bump extends into the guide vane flow channel defined between two adjacent stator airfoils.

7. Gas turbine according to claim 1 , wherein each bump surrounds a front portion of a stator airfoil.

8. Gas turbine according to claim 1 , wherein said bumps define an inner and/or outer sinusoidal stator wall facing the gap.

9. Gas turbine according to claim 1 , wherein said axisymmetric border of the inner and/or outer stator wall facing the gap is circular in shape.

10. Gas turbine according to claim 1 , comprising:

a gap between at least one of the inner stator wall and the inner rotor wall, and the outer stator wall and the outer rotor wall.

11. Gas turbine according to claim 10 , wherein said bumps define an inner and/or outer sinusoidal stator wall facing the gap.

12. Gas turbine according to claim 1 , wherein said axisymmetric border of the inner and/or outer stator wall facing the at least one gap between at least one of the inner stator wall and the inner rotor wall and the outer stator wall and the outer rotor wall is circular in shape.

13. Gas turbine comprising:

an annular combustion chamber defined by an inner wall and an outer wall;

a stator airfoil row defined by an annular inner stator wall and an annular outer stator wall housing a plurality of stator airfoils, and at least a rotor airfoil row defined by an annular inner rotor wall and an annular outer rotor wall housing a plurality of rotor airfoils; and

a gap between at least one of the inner stator wall and the inner rotor wall, and the outer stator wall and the outer rotor wall, upstream of said stator airfoil row, wherein a border of at least one of the inner and outer stator wall facing the gap is axisymmetric, and a zone of the at least one inner and outer stator wall downstream of the gap and upstream of the stator airfoils is non-axisymmetric and defines bumps arranged to locally increase static pressure of a fluid flow passing through said stator airfoil row to increase uniformity of the static pressure.

14. Gas turbine according to claim 13 , wherein each bump is located in regions where the static pressure of the hot gas flow is lowest.

15. Gas turbine according to claim 14 , wherein said bumps are located along a circumference of at least one of the inner and outer stator walls.

16. Gas turbine according to claim 14 , wherein each bump faces a guide vane flow channel defined between two adjacent stator airfoils.

17. Gas turbine according to claim 16 , wherein each bump is closer to a suction side than to a pressure side of said two adjacent stator airfoils defining said guide vane flow channel.

18. Gas turbine according to claim 13 , wherein said bumps define an inner and/or outer sinusoidal stator wall facing the gap.

19. Gas turbine comprising:

an annular combustion chamber defined by an inner wall and an outer wall;

a stator airfoil row defined by an annular inner stator wall and an annular outer stator wall housing a plurality of stator airfoils, and at least a rotor airfoil row defined by an annular inner rotor wall and an annular outer rotor wall housing a plurality of rotor airfoils; and

a gap between at least one of the inner stator wall and the inner combustion chamber wall, and the outer stator wall and the outer combustion chamber wall, upstream of said stator airfoil row, wherein a border of at least one of the inner and outer stator wall facing the gap is axisymmetric and at least partly outside of the gap, and a zone of the at least one inner and outer stator wall downstream of the gap and upstream of the stator airfoils is non-axisymmetric and defines bumps arranged to locally increase static pressure of a fluid flow passing through said stator airfoil row to increase uniformity of the static pressure.