Internally cooled airfoil for a rotary machine

1. An internally cooled casted airfoil for a rotary machine, comprising:

a suction side wall and a pressure side wall each extending in an axial direction from a leading edge region to a trailing edge region of said airfoil;

at least one suction wall sided cooling channel extending in the axial direction confined by the suction side wall and a first inner wall;

at least one pressure wall sided cooling channel extending in the axial direction confined by the pressure side wall and a second inner wall; and

at least one feed chamber being defined between said first and second inner wall for feeding a cooling fluid to said at least one suction and pressure sided cooling channel, each by at least one through hole inside of said first and second inner wall from the feed chamber toward a trailing edge,

wherein said at least one suction wall sided cooling channel and said at least one pressure wall sided cooling channel extend into the trailing edge region separately, and said at least one suction wall sided cooling channel and said at least one pressure wall sided cooling channel join before discharging at the trailing edge, wherein at least one axial rib is arranged in a common channel region where the at least one suction wall sided cooling channel and the at least one pressure wall sided cooling channel join, the at least one axial rib extending from the suction side wall to the pressure side wall and partially into the suction wall sided cooling channel, a terminal end of the at least one axial rib nearest the leading edge terminating downstream of the at least one feed chamber in a coolant fluid flow direction.

2. The internally cooled casted airfoil according to claim 1 , wherein the at least one suction wall sided cooling channel and the at least one pressure wall sided cooling channel join at the common channel region which joins a discharge channel open to the pressure side at the trailing edge.

3. The internally cooled airfoil according to claim 2 , wherein the suction side wall and the pressure side wall are each of essentially constant wall thickness along the axial direction at least in the trailing edge region, except the region of the discharge channel, along which the wall thickness becomes smaller in at least of one of the suction or pressure side walls.

4. The internally cooled casted airfoil according to claim 2 , comprising:

at least one pin arranged in the common channel region, the at least one pin connects the suction and the pressure side wall facing each other.

5. The internally cooled casted airfoil according to claim 2 , wherein along the suction wall sided cooling channel, the at least one axial rib is arranged for reducing a cross-sectional area of the cooling channel respectively.

6. The internally cooled casted airfoil according to claim 2 , wherein the first and second inner wall are designed in the common channel region such that the cross-sectional area of the suction wall sided cooling channel becomes larger while the cross-sectional area of the pressure wall sided cooling channel remains constant before joining.

7. The internally cooled casted airfoil according to claim 2 , wherein at least two separate suction wall sided cooling channels are arranged by a radial distance each confined by the suction side wall and the first inner wall.

8. The internally cooled casted airfoil according to claim 7 , wherein at least two separate pressure wall sided cooling channels are arranged by a radial distance each confined by the pressure side wall and the second inner wall.

9. The internally cooled casted airfoil according to claim 8 , wherein the common channel region is in a form of a continuous cavity which has an axial and radial extension, into which the at least two separate pressure wall sided cooling channels and/or at least two separate suction wall sided cooling channels enter and at least one of the two suction wall sided cooling channels and at least one of the two pressure wall sided cooling channels join at a common channel region which joins a discharge channel open to the pressure side at the trailing edge.

10. The internally cooled casted airfoil according to claim 1 , wherein the airfoil is used as vane and/or blade within a turbine stage of a gas turbine engine.

11. A gas turbine engine, comprising:

the internally cooled casted airfoil according to claim 1 .