Turbine blade and gas turbine including the same
Disclosed herein is a turbine blade having a leading edge, a trailing edge, a pressure side, and a suction side and having a cooling passage formed therein. The turbine blade includes a plurality of cooling holes formed on the pressure side or the suction side. Each of the cooling holes includes, a through-hole having a circular cross-section and angled outwardly toward the pressure side or the suction side from the cooling passage, a circular sink formed concavely with respect to the pressure side or the suction side in the vicinity of an upstream side of an exit of the through-hole, and an elliptical sink formed concavely with respect to the pressure side or the suction side in the vicinity of a downstream side of the exit of the through-hole.
1. A turbine blade having a leading edge, a trailing edge, a pressure side, and a suction side and having a cooling passage formed therein, the turbine blade comprising:
a plurality of cooling holes formed on the pressure side or the suction side, wherein each of the cooling holes comprises:
a through-hole having a circular cross-section and angled outwardly toward the pressure side or the suction side from the cooling passage;
a circular sink formed concavely with respect to the pressure side or the suction side and located in a first position that includes an upstream side of an exit of the through-hole; and
an elliptical sink formed concavely with respect to the pressure side or the suction side and located in a second position that includes a downstream side of the exit of the through-hole,
wherein an upstream edge of the circular sink where the circular sink meets an upstream surface has an upstream end located relatively more upstream than the upstream side of the exit of the through-hole,
wherein the circular sink comprises:
a first concave curved part formed concavely around the upstream side of the exit of the through-hole and having an arc rim, the first concave curved part meeting the upstream surface at the upstream edge; and
a curved connection part connected to the elliptical sink from one side of the first concave curved part.
2. The turbine blade according to claim 1 , wherein the through-hole is inclined at an angle of 30 to 60 degrees with respect to the pressure side or the suction side.
3. The turbine blade according to claim 1 , wherein the upstream edge where the first concave curved part meets an upstream surface is bent to create a vortex.
4. The turbine blade according to claim 1 , wherein the elliptical sink has a major axis perpendicular to a direction of flow of fluid.
5. The turbine blade according to claim 1 , wherein the elliptical sink comprises:
a second concave curved part formed concavely around the downstream side of the exit of the through-hole and having an elliptical rim; and
a convex curved part connected to a downstream surface from the elliptical rim of the second concave curved part.
6. The turbine blade according to claim 1 , wherein the circular sink has a diameter that is larger than a minor axis and smaller than a major axis of the elliptical sink.
7. The turbine blade according to claim 6 , wherein the major axis of the elliptical sink is 3 to 4 times the diameter of the through-hole.
8. The turbine blade according to claim 1 , wherein a lowest depth point of the elliptical sink from the surface of the turbine blade is deeper than a lowest depth point of the circular sink from the surface of the turbine blade.
9. A gas turbine comprising:
a compressor configured to suck and compresses outside air;
a combustor configured to mix fuel with the air compressed by the compressor to burn a mixture thereof; and
a turbine having turbine blades mounted in a turbine casing, the turbine blades being rotated by combustion gas discharged from the combustor,
wherein each of the turbine blades comprises a plurality of cooling holes formed on a pressure side or a suction side, and
wherein each of the cooling holes comprises:
a through-hole having a circular cross-section and angled outwardly toward the pressure side or the suction side from a cooling passage;
a circular sink formed concavely with respect to the pressure side or the suction side and located in a first position that includes an upstream side of an exit of the through-hole; and
an elliptical sink formed concavely with respect to the pressure side or the suction side and located in a second position that includes a downstream side of the exit of the through-hole,
wherein an upstream edge of the circular sink where the circular sink meets an upstream surface has an upstream end located relatively more upstream than the upstream side of the exit of the through-hole,
wherein the circular sink comprises:
a first concave curved part formed concavely around the upstream side of the exit of the through-hole and having an arc rim, the first concave curved part meeting the upstream surface at the upstream edge; and
a curved connection part connected to the elliptical sink from one side of the first concave curved part.
10. The gas turbine according to claim 9 , wherein the through-hole is inclined at an angle of 30 to 60 degrees with respect to the pressure side or the suction side.
11. The gas turbine according to claim 9 , wherein the upstream edge where the first concave curved part meets an upstream surface is bent to create a vortex.
12. The gas turbine according to claim 9 , wherein the elliptical sink has a major axis perpendicular to a direction of flow of fluid.
13. The gas turbine according to claim 9 , wherein the elliptical sink comprises:
a second concave curved part formed concavely around the downstream side of the exit of the through-hole and having an elliptical rim; and
a convex curved part connected to a downstream surface from the elliptical rim of the second concave curved part.
14. The gas turbine according to claim 9 , wherein the circular sink has a diameter that is larger than a minor axis and smaller than a major axis of the elliptical sink.
15. The gas turbine according to claim 14 , wherein the major axis of the elliptical sink is 3 to 4 times the diameter of the through-hole.
16. The gas turbine according to claim 9 , wherein a lowest depth point of the elliptical sink from the surface of the turbine blade is deeper than a lowest depth point of the circular sink from the surface of the turbine blade.