Manufacturing methods for multi-lobed cooling holes

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.