Manufacturing methods for multi-lobed cooling holes

1. A method for producing a diffusion cooling hole extending between a wall having a first wall surface and a second wall surface, the method comprising:

forming a cooling hole inlet at the first wall surface;

forming a cooling hole outlet at the second wall surface;

forming a metering section downstream from the inlet; and

forming a multi-lobed diffusing section between the metering section and the outlet,

wherein forming the diffusing section comprises:

forming a first lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge;

forming a second lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge; and

forming a third lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge;

wherein the inlet, outlet, metering section and ,multi-lobed diffusing section are formed by a technique selected from the group consisting of laser drilling, particle beam machining, fluid jet guided laser machining, mechanical machining, masking and combinations thereof.

2. The method of claim 1 , wherein the wall comprises a metal or superalloy substrate.

3. The method of claim 1 , wherein the second wall surface comprises a coating, and wherein at least a portion of the cooling hole extends through the coating.

4. The method of claim 3 , wherein the coating comprises:

a bond coating; and

a thermal barrier coating.

5. The method of claim 4 , wherein a portion of the diffusing section is located within the coating.

6. The method of claim 5 , wherein the entire diffusing section is located within the coating.

7. The method of claim 6 , wherein a portion of the metering section is located within the coating.

8. The method of claim 1 , wherein the inlet and metering section are formed using a first laser having a frequency between about 5 Hz and about 200 kHz and a millisecond (10 −3 ) to nanosecond (10 −9 ) pulse duration range, and wherein the multi-lobed diffusing section and outlet are formed using a second laser having a frequency between about 1 kHz and about 200 kHz and a pulse duration range from nanoseconds (10 −9 ) to femtoseconds (10 −15 ) seconds.

9. The method of claim 8 , wherein the wall comprises a coating on the second wall surface, and wherein at least a portion of the cooling hole extends through the coating.

10. The method of claim 1 , wherein the inlet, metering section, multi-lobed diffusing section and outlet are formed using a fluid jet guided laser.

11. The method of claim 10 , wherein the wall comprises a coating on the second wall surface, and wherein at least a portion of the cooling hole extends through the coating.

12. The method of claim 1 , wherein the inlet, metering section, multi-lobed diffusing section and outlet are formed using a particle beam.

13. The method of claim 12 , wherein the particle beam is an electron beam.

14. The method of claim 12 , wherein the particle beam is an ion beam or molecular beam.

15. The method of claim 13 , wherein the wall comprises a coating on the second wall surface, and wherein at least a portion of the cooling hole extends through the coating.

16. The method of claim 1 , wherein the inlet, metering section, multi-lobed diffusing section and outlet are formed by a technique selected from the group consisting of drilling, milling, grinding, superabrasive machining and combinations thereof.

17. The method of claim 1 , wherein the inlet and metering section are formed by drilling, and wherein the multi-lobed diffusing section and outlet are formed using a laser having a frequency between about 1 kHz and about 200 kHz and a pulse duration range from nanoseconds (10 −9 ) to femtoseconds (10 −15 ).

18. The method of claim 1 , wherein the inlet and metering section are formed using a laser having a frequency between about 5 Hz and about 200 kHz, and a millisecond (10 −3 ) to nanosecond (10 −9 ) pulse duration range, and wherein the multi-lobed diffusing section and outlet are formed by a technique selected from the group consisting of drilling, milling, grinding, superabrasive machining and combinations thereof.

19. The method of claim 3 , wherein the outlet and the portion of the diffusing section extending through the coating are formed by masking.

20. The method of claim 1 , wherein the metering section and the diffusing section are formed using different techniques.

21. The method of claim 1 , wherein the inlet and the metering section are formed before the diffusing section and the outlet.

22. The method of claim 1 , wherein the inlet and the metering section are formed after the diffusing section and the outlet.

23. A method for producing a diffusion cooling hole extending between a wall having a first wall surface and a second wall surface, the method comprising:

forming a cooling hole inlet at the first wall surface;

forming a cooling hole outlet at the second wall surface;

forming a metering section downstream from the inlet; and

forming a multi-lobed diffusing section between the metering section and the outlet,

wherein forming the diffusing section comprises:

forming a first lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge;

forming a second lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge; and

forming a third lobe that diverges longitudinally and laterally from a center axis of the metering section and has a trailing edge;

wherein the inlet and metering section are formed by a first technique selected from the group consisting of laser drilling, particle beam machining, fluid jet guided laser machining, mechanical machining and masking, and wherein the outlet and multi-lobed diffusing section are formed by a second technique different from the first technique and selected from the group consisting of laser drilling, particle beam drilling, fluid jet guided laser machining, mechanical machining and masking.