Cooling of turbine blades
A method for casting a turbine blade body comprises; providing a mold defining the external geometry of the blade body; providing a core defining an internal geometry of the blade body, the core comprising a main body defining an internal chamber of the blade body and having a root end and a tip end and a plurality of pedestals defining an array of cooling channels extending from the internal chamber; casting a molten material between the mold and the core; and removing the core after the molten material has solidified, wherein the pedestals are arranged in a single row starting from the root end to a mid-portion of the main body branching into multiple and divergent rows towards the tip end of the body.
1. A method for casting a turbine blade body, the method comprising;
providing a mould defining the external geometry of the blade body;
providing a core defining an internal geometry of the blade body, the core comprising a main body defining an internal chamber of the blade body and having a root end and a tip end and a plurality of pedestals defining an array of cooling channels extending from the internal chamber;
casting a molten material between the mould and the core; and
removing the core after the molten material has solidified, wherein
the pedestals are arranged in a single row starting from the root end to the main body branching into multiple rows towards the tip end of the body, the single row having a line of symmetry and all of the multiple rows branching to either side of the line of symmetry, and one or more of the pedestals has a larger cross sectional area than the remaining pedestals and a pedestal of larger cross sectional area is positioned at or near the root end of the core body.
2. A method as claimed in claim 1 wherein the number of branches is two.
3. A method as claimed in claim 2 wherein the arrangement of pedestals branches into a pair of rows arranged symmetrically about the line of symmetry.
4. A method as claimed in claim 2 wherein the arrangement of pedestals branches into a pair of rows arranged asymmetrically about the line of symmetry.
5. A method as claimed in claim 1 , wherein a pedestal of larger cross sectional area is positioned at or near the tip end of the core body.
6. A method as claimed in claim 1 , wherein some or all of the pedestals are grouped into numbers of pedestals with equal cross sectional areas.
7. A method as claimed in claim 1 wherein the pedestals have a cross-sectional shape selected from; circular, elliptical or race track.
8. A method as claimed in claim 1 wherein the pedestals are inclined to a surface of the main body and the resulting blade body includes channels which are inclined to surfaces of walls of the blade body.
9. A method as claimed in claim 1 wherein the single row branches at a position which is closer to the root end than to the tip end.
10. A method as claimed in claim 1 wherein the single row branches at a position in the range from 20% to 80% of the distance from the root end to the tip end.
11. A method as claimed in claim 10 wherein the single row branches at a position in the range from 30% to 70% of the distance from the root end to the tip end.
12. A method as claimed in claim 1 wherein the multiple rows diverge from the single row for at least part of the distance to the tip end.