Gas path components of gas turbine engines and methods for cooling the same using porous medium cooling systems
Gas path components of gas turbine engines and methods for cooling the same using porous medium cooling systems are provided. The gas path component comprises a wall at least partially defining a cooling plenum and a porous medium cooling system. The wall includes a wall surface comprising a gas path surface and an opposing wall surface proximate the cooling plenum. The porous medium cooling system is disposed between the cooling plenum and the opposing wall surface. The porous medium cooling system comprises a perforated baffle and a porous material layer disposed between and adjacent the perforated baffle and the opposing wall surface. The wall includes a plurality of openings in fluid communication with the cooling plenum via the porous medium cooling system.
1. A method for cooling a gas path component comprising a wall at least partially defining a cooling plenum, the wall having a wall surface comprising a gas path surface and an opposing wall surface proximate the cooling plenum, the method comprising the steps of:
forming a porous medium cooling system in the gas path component by:
applying a first bond coating layer in a hollow cast of the gas path component on the opposing wall surface, the hollow cast of the gas path component having at least one open end;
applying a low density porous metallic foam in the hollow cast of the gas path component, the low density porous metallic foam having a porosity of about 75% to about 95% of the volume consisting of void spaces;
bonding the porous material layer to the opposing wall surface by the first bond coating layer;
applying a second bond coating layer to an outer surface of a tubular perforated baffle;
inserting the perforated baffle into the at least one open end of the hollow cast such that the perforated baffle is positioned between the cooling plenum and the porous metallic foam;
bonding the porous metallic foam to the perforated baffle by the second bond coating layer such that the porous metallic foam is bonded to the perforated baffle substantially over a perimeter of the baffle; and
after bonding the porous material layer to the opposing wall surface, forming a plurality of openings through the wall of the gas path component, each opening having an outlet opening onto the gas path surface and the plurality of openings having an inlet in fluid communication with the porous metallic foam to receive cooling medium for cooling the gas path component.
2. The method of claim 1 , wherein the forming the plurality of openings comprises forming a plurality of film cooling holes.
3. The method of claim 1 , wherein the forming the plurality of openings comprises forming a plurality of film cooling holes, a plurality of trailing edge slots at the trailing edge of the turbine blade, or both film cooling holes and trailing edge slots.
4. The method of claim 1 , wherein the gas path component comprises a turbine blade having a body that defines the wall, the method further comprising the step of:
applying an additional porous metallic foam layer over a first open end of the perforated baffle for tip cooling; and
connecting a blade tip cap to the body to seal the at least one open end after the forming and positioning steps.