INTERTURBINE VANE WITH MULTIPLE AIR CHAMBERS

• US 20110081228A1
• Filed: 10/01/2009
• Published: 04/07/2011
• Est. Priority Date: 10/01/2009
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: GRIVAS, Nicolas, DUROCHER, Eric
• Granted Patent: US 8,511,969 B2
• Time in Patent Office: Days
• US Class Current: 415/115
• CPC Class Codes: F01D 11/005 Sealing means between non relatively rotating elements
• CPC Class Codes: F01D 25/14 Casings modified therefor double casings F01D25/26
• CPC Class Codes: F01D 25/28 Supporting or mounting arrangements, e.g. for turbine casing
• CPC Class Codes: F01D 5/18 Hollow blades, i.e. blades with cooling or heating channels or cavities structure of hollow blades in general F01D5/147; Heating, heat-insulating or cooling means on blades
• CPC Class Codes: F05D 2260/20 Heat transfer, e.g. cooling

Abstract

A gas turbine engine has a mid turbine frame disposed between turbine rotor assemblies. The mid turbine frame includes hollow airfoils radially extending through an annular gas path duct. The airfoils each include a double-walled leading edge structure to define a front chamber separated from a rear chamber defined in the remaining space within the airfoil.

Claims

1. A gas turbine engine comprising:

a mid turbine frame (MTF) disposed axially between first and second turbine rotors, the MTF including an annular outer case, an annular inner case and a plurality of load spokes radially extending between and interconnecting the outer and inner cases;

an annular inter-turbine duct (ITD) disposed radially between the outer and inner case of MTF, the ITD including an annular outer duct wall and annular inner duct wall, an annular hot gas path between the outer and inner duct walls, and a plurality of hollow airfoils radially extending between and interconnecting the outer and inner duct walls;

a first annular cavity defined between the annular outer case and the outer duct wall, and a second annular cavity defined between the annular inner duct wall and the inner case, the first and second cavities in fluid communication with an inner space in the respective hollow airfoils;

each of the hollow airfoils including a double-walled leading edge structure, thereby defining a front chamber in the structure separated from a rear chamber defined in a remaining space within the hollow airfoil, the rear chamber of at least a number of the hollow airfoils accommodating one said spoke to pass therethrough;

an annular first seal housing disposed in the first cavity, thereby defining an annular outer front cavity between the first seal housing and an upstream section of the outer duct wall, the outer front cavity being separated from the first cavity; and

an annular second seal housing disposed in the second cavity, thereby defining an annular inner front cavity between an upstream section of the inner duct wall and the second seal housing, the inner front cavity being separated from the second cavity, the outer and inner front cavities being in fluid communication with the front chamber of the respective airfoils.

2. The gas turbine engine as defined in claim 1 further comprising a flow restricting inlet for allowing limited cooling air to be introduced into the front chamber in the respective airfoils while preventing massive hot gases from escaping from the front chamber into the first, second cavities and the respective rear chambers when cracks occur on a leading edge of one of the airfoils.

3. The gas turbine engine as defined in claim 2, wherein the flow restricting inlet comprises at least one metering hole defined in the second seal housing for introducing limited cooling air contained in the second cavity through the inner front cavity into the rear chamber of the respective airfoils.

4. The gas turbine engine as defined in claim 1 wherein the load spokes are hollow and extend radially through the rear chamber of the respective hollow airfoils, the hollow spokes directing a cooling air flow radially inwardly into the inner case which is in fluid communication with, and allows the cooling air flow to enter into the first and second cavities and the rear chamber in the respective airfoils.

5. The gas turbine engine as defined in claim 1, wherein the double-walled leading edge structure comprises at least one metering hole for purging a limited cooling air flow from the front chamber into the hot gas path while maintaining the front chamber pressurized.

6. The gas turbine engine as defined in claim 1, wherein the upstream section of the outer duct wall comprises at least one metering hole for purging a limited cooling air flow from the outer front cavity into the hot gas path while maintaining the outer front cavity pressurized.

7. The gas turbine engine as defined in claim 1, wherein the upstream section of the inner duct wall comprises at least one metering hole for purging a limited cooling air flow from the inner front cavity into the hot gas path while maintaining the inner front cavity pressurized.

8. The gas turbine engine as defined in claim 1, wherein a front end of the annular first seal housing is connected to an upstream section of the outer case with a first seal, and wherein a rear end of the annular first seal housing is connected to the outer duct wall at an axial location with a second seal, the axial location being downstream of a first opening of the front chamber of the respective airfoils in respect to the direction of the hot gases passing through the ITD, the first opening being defined in the upstream section of the outer duct wall.

9. The gas turbine engine as defined in claim 1, wherein a front end of the annular second seal housing is connected to a front end of the inner duct wall with a third seal and wherein a rear end of the annular second seal housing is connected to the inner duct wall at an axial location with a fourth seal, the axial location being downstream of a second opening of the front chamber of the respective airfoils, the second opening being defined in the upstream section of the inner duct wall.

10. The gas turbine engine as defined in claim 1, wherein the outer and inner duct walls comprise at least one metering hole for purging limited cooling air from the first and second cavities into the hot gas path.

11. A gas turbine engine comprising:

a mid turbine frame (MTF) disposed axially between first and second turbine rotors, the MTF including an annular outer case, an annular inner case and a plurality of load spokes radially extending between and interconnecting the outer and inner cases to transfer loads from the inner case to the outer case;

an annular inter-turbine duct (ITD) disposed radially between the outer and inner case of MTF, the ITD including an annular outer duct wall and annular inner duct wall, thereby defining an annular hot gas path between the outer and inner duct walls for directing hot gases from the first turbine rotor therethrough to the second turbine rotor, a plurality of hollow airfoils radially extending between and interconnecting the outer and inner duct walls;

each of the hollow airfoils including a double-walled leading edge structure, thereby defining a front chamber in the structure separated from a rear chamber defined in a remaining space within the hollow airfoil, the rear chamber of at least a number of the hollow airfoils accommodating one said spoke to pass therethrough;

a first annular cavity defined between the annular outer case and the outer duct wall and a second annular cavity defined between the annular inner duct wall and inner case, the first and second cavities being in fluid communication with the rear chamber in the respective hollow airfoils; and

an inlet attached to the front chamber of each airfoil for introducing cooling air into the front chamber of the respective airfoils independent from cooling air contained within the rear chamber of the respective airfoils.

12. The gas turbine engine as defined in claim 11, wherein the front chamber of the respective airfoils comprises a closed radial outer end and an open radial inner end defining the inlet.

13. The gas turbine engine as defined in claim 12, wherein the inlet comprises a tube fitting for receiving a tube to introduce cooling air.

14. The gas turbine engine as defined in claim 11 wherein the load spokes are hollow and extend radially through the rear chamber of the respective hollow airfoils, the hollow spokes directing a cooling air flow radially inwardly into the inner case which is in fluid communication with, and allows the cooling air flow to enter into the first and second cavities and the rear chamber in the respective airfoils.

15. The gas turbine engine as defined in claim 11, wherein the double-walled leading edge structure comprises at least one metering hole for purging a limited cooling air flow from the front chamber into the hot gas path while maintaining the front chamber pressurized.

16. The gas turbine engine as defined in claim 11, wherein the double-walled leading edge structure comprises at least one metering hole for purging a limited cooling air flow from the front chamber into the rear chamber while maintaining the front chamber pressurized.

17. The gas turbine engine as defined in claim 11, wherein the outer and inner duct walls comprise at least one metering hole for purging cooling air from the first and second cavities into the hot gas path.

18. A gas turbine engine comprising:

an annular inter-turbine duct (ITD) disposed radially between annular outer and inner engine cases, the ITD including an annular outer duct wall and annular inner duct wall, an annular hot gas path between the outer and inner duct walls, and a plurality of hollow airfoils radially extending between and interconnecting the outer and inner duct walls,

a first annular cavity defined between the annular outer case outer duct wall and a second annular cavity defined between the annular inner duct wall and inner case, the first and second cavities in fluid communication with an inner space in the respective hollow airfoils;

each of the hollow airfoils including an inner front wall disposed near a leading edge of the airfoil, extending radially through the airfoil and circumferentially between two opposed side walls of the airfoil, the front wall being connected to at least one of the outer and inner duct walls, thereby defining a front chamber between the inner front wall and the leading edge separated from a rear chamber defined in a remaining space within the hollow airfoils.

19. The gas turbine engine as defined in claim 18, wherein a mid turbine frame (MTF) provides the outer and inner engine cases, the MTF disposed axially between first and second turbine rotors, the MTF including an annular outer case, an annular inner case and a plurality of load spokes radially extending between and interconnecting the outer and inner cases;

20. The gas turbine engine as defined in claim 19, wherein the rear chamber of a plurality of the airfoils accommodates one of said spokes passing therethrough.