Blade for a gas turbine

1. A blade for a gas turbine comprising:

a leading edge running in a longitudinal direction substantially radially to an axis of the turbine;

a trailing edge running in the longitudinal direction;

a blade body disposed between the leading edge and the trailing edge so as to define a pressure side and a suction side;

an exit slot disposed in the blade body in an area of the trailing edge and running in the longitudinal direction and configured to discharge a cooling medium from an interior of the blade body; and

a row of first and second control elements disposed in the exit slot in a distributed manner so as to alternate, one after the other, between the first and second control elements in the longitudinal direction and configured to control a mass flow of the cooling medium exiting through the exit slot, the first control elements having a first edge contour and the second control elements having a second edge contour different from the first edge contour

wherein the largest cross-sectional area of each of the first control elements is larger than the largest cross-sectional area of each of the second control elements, and the largest cross-sectional area of each of the first control elements and the second control elements lie in a single plane extending across the exit slot.

2. The blade as recited in claim 1 , wherein the first cross-sectional contour includes an elongated cross-sectional form extending in a direction of flow of the cooling medium, and wherein the second cross-sectional contour includes a substantially circular cross-sectional form.

3. The blade as recited in claim 2 , wherein the elongated cross-sectional form includes a drop-shape extending beyond the exit slot.

4. The blade as recited in claim 1 , wherein the exit slot is disposed at a distance in front of the trailing edge.

5. The blade as recited in claim 4 , wherein the exit slot is disposed on the pressure side.

6. The blade as recited in claim 1 wherein the exit slo; includes a through-flow wall and wherein at least one of the first and the second control elements is formed with a head-side gap disposed opposite the through-tlow wall relative to a cross- sectional width of the exit slot.

7. The blade as recited in claim 6 , wherein the air gap has a varying thickness along the row.

8. The blade as recited in claim 1 , wherein the first and second control elements cause a cross-sectional narrowing of the mass flow through the exit slot of between 20% and 90%.