A turbine blade for a gas turbine has a hollow airfoil extending from a platform. There is a fillet between the airfoil and the platform, both on the pressure side and on the suction side of the airfoil. The fillet contains a cooling bore extending along part of the length of the fillet, having a first end communicating with the interior of the turbine blade for receiving a gaseous coolant and a second end communicating with the exterior of the turbine blade. The cooling may be formed by electro-discharge machining.
1. A turbine blade for a gas turbine, comprising a hollow airfoil extending from a platform, there being a fillet between the airfoil and the platform on a pressure side or a suction side of the airfoil, the fillet extending on a longitudinal direction along the outer circumference of the airfoil, the fillet containing a cooling bore extending along the longitudinal direction for a part of the length of the fillet, the cooling bore having a first end communicating with the interior of the turbine blade for receiving a gaseous coolant and a second end communicating with the exterior of the turbine blade.
2. The turbine blade as claimed in claim 1 , wherein the first end of the cooling bore is inside the platform.
3. The turbine blade as claimed in claim 2 , wherein the first end of the cooling bore in the interior of the platform is formed as a groove in the platform.
4. The turbine blade as claimed in claim 1 , wherein the second end of the cooling bore is at the exit side of the turbine blade.
5. The turbine blade as claimed in claim 1 , wherein the second end of the cooling bore is adjacent the trailing edge of the airfoil.
6. The turbine blade as claimed in claim 1 , wherein the cooling bore is straight.
7. The turbine blade as claimed in claim 1 , wherein the cooling bore is curved.
8. The turbine blade as claimed in claim 7 , wherein the cooling bore has a substantially constant radius of curvature.
9. The turbine blade as claimed in claim 1 , wherein the cooling bore has a diameter of approximately 1 mm.
10. The turbine blade as claimed in claim 1 wherein the cooling bore has a length of at least 5 cm.
11. The turbine blade as claimed in claim 1 , further comprising two cooling bores, one in the fillet on the pressure side and the other in the fillet on the suction side.
12. The turbine blade as claimed in claim 1 , wherein the cooling bore is formed by electro-discharge machining.
13. The turbine blade as claimed in claim 1 , wherein the turbine blade is a guide blade or a moving blade.
14. The turbine blade as claimed in claim 1 , wherein the fillet is on the pressure side.
15. The turbine blade as claimed in claim 1 , wherein the fillet is on the suction side.