Turbine airfoil with trailing edge cooling channels
A turbine airfoil such as a turbine stator vane used in an industrial gas turbine engine, the vane including a trailing edge region having a thin wall cooling channel arrangement of mini cooling channels formed by a series of rows of elongated flow blockers that form the mini cooling channels between adjacent flow blockers. The adjacent row of flow blockers are offset from the each other such that the inlet and the outlet flow of cooling air is discharged directly onto the flow blocker in order to produce impingement cooling. The mini cooling channels have a spacing to hydraulic diameter ratio of less than 4.0 and a mini channel length to hydraulic diameter ratio of 5.0 of less in order to maintain a high flow velocity within the mini channels. In one embodiment, the flow blockers have a progressively decreasing length in the flow direction of the cooling air.
1. A turbine stator vane comprising:
a cooling air impingement cavity extending in a spanwise direction of the vane for supplying cooling air to the vane, the impingement cavity being located adjacent to a trailing edge region of the vane;
a first row of ribs formed within the trailing edge region of the vane, the first row of ribs extending between the pressure side wall and the suction side wall of the vane, the first row of ribs forming first mini cooling channels;
a second row of ribs formed within the trailing edge region of the vane, the second row of ribs extending between the pressure side wall and the suction side wall of the vane, the second row of ribs forming second mini cooling channels,
the second row of ribs being staggered with respect to the first row of ribs such that cooling air discharging from the first mini channels impinges onto the leading edge of the second row of ribs; and
wherein all of the ribs are elongated in an axial direction and the ribs of the first row have an axial length greater than the axial length of the ribs of the second row.
2. The turbine stator vane of claim 1 , and further comprising:
a third row of ribs formed within the trailing edge region of the vane, the third row of ribs extending between the pressure side wall and the suction side wall of the vane, the third row of ribs forming third mini cooling channels; and,
the third row of ribs being staggered with respect to the second row of ribs such that cooling air discharging from the second mini channels impinges onto the leading edge of the third row of ribs.
3. The turbine stator vane of claim 2 , and further comprising:
the axial length of the ribs of the second row is greater than the axial length of the ribs of the third row.
4. The turbine stator vane of claim 3 , and further comprising:
the rows of ribs are spaced from each other a distance Zn such that a ratio of the spacing Zn to a hydraulic diameter Dh is less than or equal to 4.
5. The turbine stator vane of claim 4 , and further comprising:
a ratio of the first and the second mini cooling channels length to the hydraulic diameter is less than or equal to 5.
6. The turbine stator vane of claim 3 , and further comprising:
a fourth row of ribs formed within the trailing edge region of the vane, the fourth row of ribs extending between the pressure side wall and the suction side wall of the vane, the fourth row of ribs forming fourth mini cooling channels; and,
the fourth row of ribs being staggered with respect to the third row of ribs such that cooling air discharging from the third mini channels impinges onto the leading edge of the fourth row of ribs; and,
the fourth cooling mini channels opening onto an exit of the vane.
7. The turbine stator vane of claim 1 , and further comprising:
the leading edge of the second row of ribs is spaced from the trailing edge of the first row of ribs a distance Zn such that a ratio of the spacing Zn to a hydraulic diameter Dh is less than or equal to 4.
8. The turbine stator vane of claim 7 , and further comprising:
a ratio of the first and the second mini cooling channels length to the hydraulic diameter is less than or equal to 5.
9. The turbine stator vane of claim 1 , and further comprising:
a ratio of the first and the second mini cooling channels length to a hydraulic diameter is less than or equal to 5.