Method and Apparatus to Enhance Laminar Flow for Gas Turbine Engine Components

1 . A gas turbine engine component comprising:

a component body configured to be positioned within a flow path of a gas turbine engine, wherein the component body includes at least one internal cavity;

at least one inlet opening formed in an outer surface of the component body to direct flow into the at least one internal cavity; and

at least one outlet from the internal cavity, wherein the at least one outlet is located at a lower pressure area in the internal cavity than the at least one inlet opening such that flow is drawn into the internal cavity from the at least one inlet opening and expelled out the at least one outlet.

2 . The gas turbine engine component according to claim 1 wherein the component body comprises at least one of an airfoil in a turbine or compressor, a platform, or a transition duct.

3 . The gas turbine engine component according to claim 2 wherein the component body comprises an airfoil having a leading edge, a trailing edge, and pressure and suction side walls extending from the leading edge to the trailing edge, and wherein the airfoil extends from a base to a tip.

4 . The gas turbine engine component according to claim 3 wherein the at least one inlet opening comprises a plurality of inlet openings formed in one or both of the pressure and suction side walls.

5 . The gas turbine engine component according to claim 3 wherein the leading edge is free from inlet openings.

6 . The gas turbine engine component according to claim 3 wherein the at least one outlet comprises at least one opening to the external surface that is located near or at the trailing edge.

7 . The gas turbine engine component according to claim 1 wherein the component body is not subjected to cooling airflow.

8 . The gas turbine engine component according to claim 1 wherein flow is drawn into the internal cavity to maintain laminar boundary layer attachment along the component body.

9 . The gas turbine engine component according to claim 1 wherein spacing between adjacent holes or slots is on the order of 10:1 to 20:1 as a ratio of a distance along the outer surface between the adjacent holes or slots to a width of the holes or slots.

10 . A gas turbine engine comprising:

an airfoil configured to be positioned within a flow path of a gas turbine engine, the airfoil having a leading edge, a trailing edge, and pressure and suction side walls extending from the leading edge to the trailing edge, and wherein the airfoil includes at least one internal cavity;

at least one inlet opening formed in an outer surface of the airfoil to direct flow into the at least one internal cavity; and

at least one outlet from the internal cavity, wherein the at least one outlet is located at a lower pressure area in the internal cavity than the at least one inlet opening such that flow is drawn into the internal cavity from the at least one inlet opening and expelled out the at least one outlet.

11 . The gas turbine engine according to claim 10 wherein the at least one inlet opening comprises a plurality of inlet holes or slots.

12 . The gas turbine engine according to claim 11 wherein the plurality of inlet holes or slots are formed in at least one of the pressure and suction side walls.

13 . The gas turbine engine according to claim 12 wherein the leading edge is free from inlet holes or slots.

14 . The gas turbine engine according to claim 13 wherein the at least one outlet comprises at least one opening to the external surface that is located near or at the trailing edge.

15 . The gas turbine engine according to claim 10 wherein flow is drawn into the internal cavity to maintain laminar boundary layer attachment along the component body.

16 . The gas turbine engine according to claim 10 including:

a compressor section;

a combustor section downstream of the compressor section; and

a turbine section downstream of the combustor section, and wherein the turbine section includes at least a high pressure turbine downstream of the combustor section and a low pressure turbine downstream of the high pressure turbine, and wherein the airfoil is located within the low pressure turbine.

17 . A method of enhancing laminar flow for a gas turbine engine component comprising the steps of:

a) positioning a component body within a flow path of a gas turbine engine, wherein the component body includes at least one internal cavity;

b) directing a portion of the flow through at least one inlet opening formed in an outer surface of the component body and into the at least one internal cavity;

c) expelling the flow from the at least one internal cavity via at least one outlet from the component body; and

d) locating the at least one outlet opening at a lower pressure area in the internal cavity than the at least one inlet opening such that flow is drawn into the internal cavity from the at least one inlet opening and expelled out the at least one outlet.

18 . The method according to claim 17 wherein the component body comprises one of an airfoil, a platform or a transition duct in at least one of a mid-turbine frame or turbine exhaust case and including:

drawing flow into the internal cavity to maintain laminar boundary layer attachment along the component body.

19 . The method according to claim 18 wherein the component body comprises an airfoil having a leading edge, a trailing edge, and pressure and suction side walls extending from the leading edge to the trailing edge, and including:

forming the at least one inlet opening as a plurality of inlet openings that are formed in one of or both of the pressure and suction side walls;

forming the leading edge to be free from inlet openings; and

locating the at least one outlet near or at the trailing edge.

20 . The method according to claim 19 wherein the airfoil is free from internal cooling channels.