Enhanced film cooling system

1. A turbine blade in an industrial gas turbine, comprising:

a blade surface to be cooled by a film of cooling fluid;

a plurality of cooling holes extending through the blade surface through which cooling fluid flows, each cooling hole including an inlet portion and an outlet portion; and

at least one trench formed on the blade surface to have a width extending in an axial direction and a length extending in a radial direction, the at least one trench including a downstream wall that extends in the radial direction and has a flat continuous surface facing the outlet portion and extending the length of the at least one trench,

wherein the outlet portion of each of the plurality of cooling holes has a shape configured to generate a first stage diffusion of the cooling fluid and the downstream wall is offset in the axial direction from the outlet portion to generate a second stage diffusion of the cooling fluid, thereby forming the film of cooling fluid,

wherein the at least one trench consists of a plurality of trenches arranged in the radial direction in correspondence to an arrangement of the plurality of cooling holes, each trench of the plurality of trenches individually surrounding the outlet portion of only one cooling hole of the plurality of cooling holes, and

wherein the inlet portion and outlet portion of each of the plurality of cooling holes are offset from each other in the axial direction such that a plane, defined by a central axis of the inlet portion and an intersecting axis parallel to the axial direction, is perpendicular to the downstream wall.

2. The turbine blade of claim 1 , wherein the shape of the outlet portion of the cooling hole is a fan shape.

3. The turbine blade of claim 1 , wherein the shape of the outlet portion of the cooling hole is a trapezoidal shape.

4. The turbine blade of the claim 1 , wherein a height of the trench is equal to a thickness of a coating deposited on the blade surface.

5. A turbine, comprising:

a rotating shaft; and

one or more turbine blades connected to the rotating shaft, each turbine blade including:

a blade surf ace to be cooled by a film of cooling fluid;

a plurality of cooling holes passing through the blade surface through which cooling fluid flows, each cooling hole including an inlet portion and an outlet portion; and

at least one trench formed on the blade surface to have a width extending in an axial direction and a length extending in a radial direction, the at least one trench including a downstream wall that extends in the radial direction and has a flat continuous surface facing the outlet portion and extending the length of the at least one trench,

wherein the outlet portion of each of the plurality of cooling holes has a shape configured to generate a first stage diffusion of the cooling fluid and the downstream wall is offset in the axial direction from the outlet portion to generate a second stage diffusion of the cooling fluid, thereby forming the film of cooling fluid,

wherein the at least one trench consists of a plurality of trenches arranged in the radial direction in correspondence to an arrangement of the plurality of cooling holes, each trench of the plurality of trenches individually surrounding the outlet portion of only one cooling hole of the plurality of cooling holes, and

wherein the inlet portion and outlet portion of each of the plurality of cooling holes are offset from each other in the axial direction such that a plane, defined by a central axis of the inlet portion and an intersecting axis parallel to the axial direction, is perpendicular to the downstream wall.

6. The turbine of claim 5 , wherein the shape of the outlet portion of the cooling hole is a fan shape.

7. The turbine of claim 5 , wherein the shape of the outlet portion of the cooling hole is a trapezoidal shape.

8. The turbine of claim 5 , wherein a height of the trench is equal to a thickness of a coating deposited on the blade surface.