Turbine blade squealer tip having air cooling holes contiguous with tip interior wall surface

In a turbine blade having an interior source of cooling air flow, opposite pressure and suction sides, and an end portion with a continuous peripheral edge, a squealer tip comprising:

• (a) a continuous peripheral wall connected to, extending around, and projecting from said peripheral edge of said end portion of said blade, said continuous peripheral wall having an interior wall surface;
• and
• (b) means defining a plurality of tip holes through said end portion of said blade in communication with said interior source of cooling air flow, said tip holes being spaced apart from each other and located contiguous with said interior wall surface of said continuous peripheral wall along respectively said pressure and suction sides of said turbine blade for providing effective diffusion cooling air flow from said tip holes on portions of said interior wall surface of said continuous peripheral wall along said pressure and suction sides of said blade;
• (c) said each tip hole including
• (i) an inner portion having an inner end and an outer end and communicating with said interior source of cooling air flow of blade at said outer end, said inner hole portion along its axial extent from said outer end to inner end thereof having a cross-section with first and second orthogonal dimensions that are uniform, and
• (ii) an outer portion having an inner end and an outer end and communicating between said inner end of said inner portion of said hole and a cavity defined by said blade end portion and said peripheral wall of said squealer tip, said outer portion having opposite sides defined by spaced interior surface portions, one of said interior surface portions being formed on one of said pressure and suction sides of said blade and extending in coplanar relation with said interior wall surface of said peripheral wall, the other of said interior surface portions being formed in said end portion of said blade and spaced from said one interior wall portion and extending in generally parallel relation thereto and to said one interior wall portion such that said outer hole portion along its axial extent from said outer end to inner end thereof has a rectangular cross-section with a first dimension that is uniform and a second dimension orthogonal to the first dimension that decreases so as to define said outer hole portion overall as a rectangular trapezoid.