Convertible gas turbine propulsion system

• US 20090139202A1
• Filed: 11/29/2007
• Published: 06/04/2009
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Sirica, Steven J., Agrawal, Rajendra K., Schneider, William F.
• Granted Patent: US 8,511,058 B2
• Time in Patent Office: Days
• US Class Current: 60/226.300
• CPC Class Codes: F02C 6/206 the vehicles being airscrew driven
• CPC Class Codes: F02C 7/36 Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user F02C3/107 - F02C3/13 and F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H

Abstract

A convertible gas turbine propulsion system operates in multiple output modes. The convertible gas turbine propulsion system comprises a gas generator, a first power turbine, a secondary propulsion system and an exhaust duct. The gas generator is configured to produce exhaust gas. The first power turbine is aligned with the gas generator to receive the exhaust gas. The secondary propulsion system is in series with the gas generator and the first power turbine. The exhaust duct coaxially extends from the first power turbine to the secondary propulsion system. The exhaust duct includes an exhaust port for opening the exhaust duct to ambient air pressure and permitting exhaust gas to bypass the secondary propulsion system. In various embodiments of the invention, the first power turbine is connected to a first rotary propulsion system, and the secondary propulsion system comprises a second power turbine or a nozzle.

Claims

1. A convertible gas turbine propulsion system operable in multiple output modes, the propulsion system comprising:

a gas generator for producing exhaust gas;

a first power turbine aligned with the gas generator to receive the exhaust gas;

a secondary propulsion system in series with the gas generator and the first power turbine,

an exhaust duct coaxially extending from the first power turbine to the secondary propulsion system to direct exhaust gas into the secondary propulsion system; and

an exhaust port positioned within the exhaust duct between the first power turbine and the secondary propulsion system for selectively opening the exhaust duct to ambient air pressure to permit exhaust gas to bypass the secondary propulsion system.

2. The propulsion system of claim 1 wherein the first power turbine and the gas generator are configured as a turboshaft engine.

3. The propulsion system of claim 1 wherein the exhaust port effectively ceases powered output of the secondary propulsion system by the exhaust gas when in an open position by producing a negligible pressure differential across the secondary propulsion system.

4. The propulsion system of claim 1 wherein the exhaust gas effectively powers the secondary propulsion system when the exhaust port is in a closed position by producing an operable pressure differential across the secondary propulsion system.

5. The propulsion system of claim 1 wherein the secondary propulsion system comprises a second power turbine mechanically uncoupled from the first power turbine such that the first power turbine and the second power turbine rotate independently.

6. The propulsion system of claim 5 and further comprising:

a first shaft connected to the first power turbine for driving a first rotary output system; and

a second shaft connected to the second power turbine for driving a second rotary output system.

7. The propulsion system of claim 6 wherein:

the first rotary output system comprises a rotary propulsion system connected to the first shaft for providing vertical and horizontal thrust; and

the second rotary output system comprises a propeller propulsion system connected to the second shaft for producing horizontal thrust.

8. The propulsion system of claim 1 wherein:

the first power turbine is connected to a rotary propulsion system; and

the secondary propulsion system comprises a nozzle for accelerating the exhaust gas.

9. A gas turbine propulsion system comprising:

a primary propulsion system comprising;

a combustor for producing exhaust gas;

a gas generator turbine powered by the exhaust gas;

a first power turbine powered by the exhaust gas;

a compressor connected to the gas generator turbine; and

an annular first exhaust duct extending from the first power turbine;

a secondary propulsion system including;

an annular second exhaust duct extending aft of the first power turbine within a downstream end of the first exhaust duct to define a bypass passage; and

a retractable annular cowling radially disposed between the first exhaust duct and the second exhaust duct, wherein the cowling is adjustable between an open and a closed position for selectively closing off flow of the exhaust gas to the bypass passage.

10. The gas turbine propulsion system of claim 9 wherein:

the first annular exhaust duct is radially larger at a second end than at a first end such that

the first annular exhaust duct surrounds the second annular exhaust duct; and

the retractable cowling is positioned within the second annular exhaust duct.

11. The gas turbine propulsion system of claim 10 wherein the secondary propulsion system includes a second power turbine that is disposed within the second exhaust duct downstream of the first power turbine.

12. The gas turbine propulsion system of claim 11 wherein the second power turbine is mechanically uncoupled from the first power turbine.

13. The gas turbine propulsion system of claim 11 wherein the annular cowling controls a pressure differential across the second power turbine.

14. The gas turbine propulsion system of claim 11 wherein the annular cowling produces a greater pressure differential across the second power turbine when in the closed position as compared to a pressure differential across the second power turbine when in an open position.

15. The gas turbine propulsion system of claim 11 wherein the annular cowling opens the bypass passage to ambient pressure when in the open position.

16. The gas turbine propulsion system of claim 11 and further comprising:

a first propulsion system connected to the first power turbine; and

a second propulsion system connected to the second power turbine.

17. The gas turbine propulsion system of claim 16 wherein the first propulsion system comprises horizontal rotors and the second rotary propulsion system comprises vertical rotors.

18. The gas turbine propulsion system of claim 11 wherein the second power turbine includes variable vanes and a variable vane actuation mechanism to regulate pressure differential across the second power turbine.

19. The gas turbine propulsion system of claim 10 wherein the second annular exhaust duct comprises an exhaust nozzle such that the secondary propulsion system comprises a flow accelerating duct.

20. A gas turbine propulsion system comprising:

a gas generator for producing exhaust gas;

a first power turbine disposed downstream from the gas generator;

a first exhaust duct positioned aft of the first power turbine to define a pressure chamber, wherein the first power turbine is driven by a pressure differential between the gas generator and the pressure chamber;

a second power turbine downstream of the first power turbine within the first exhaust duct, and

a second exhaust duct extending into the pressure chamber within the first exhaust duct, wherein the second exhaust duct is selectively positioned to control a pressure differential across the second power turbine.

21. The gas turbine propulsion system of claim 20 wherein the second exhaust duct is positioned in an open configuration to produce a negligible pressure differential across the second power turbine.

22. The gas turbine propulsion system of claim 20 wherein the negligible pressure differential across the second power turbine permits the second power turbine to windmill.

23. The gas turbine propulsion system of claim 20 wherein the second exhaust duct is positioned in a closed configuration to produce a pressure differential across the second power turbine proportional to the pressure in the pressure chamber and ambient pressure aft of the second power turbine.

24. The gas turbine propulsion system of claim 20 and further comprising:

a first rotary propulsion system connected to the first power turbine; and

a second rotary propulsion system connected downstream of the first power turbine.