GEARED GAS TURBINE ENGINE

• US 20170211484A1
• Filed: 01/26/2016
• Published: 07/27/2017
• Est. Priority Date: 01/26/2016
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Sheridan, William G.
• Granted Patent: US 10,590,854 B2
• Time in Patent Office: Days
• CPC Class Codes: F02C 3/00 Gas-turbine plants characterised by the use of combustion products as the working fluid generated by intermittent combustion F02C5/00
• CPC Class Codes: F02C 3/04 having a turbine driving a compressor power transmission arrangements F02C7/36; control of working fluid flow F02C9/16
• CPC Class Codes: F02C 3/103 the compressor being of the centrifugal type
• 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
• CPC Class Codes: F05D 2260/40311 of the epicyclical, planetary or differential type

Abstract

A turboshaft engine includes a high speed spool that connects a high pressure compressor with a high pressure turbine. A low speed spool connects a low pressure compressor with a low pressure turbine. A speed change mechanism includes an input that is in communication with the low spool and a fixed gear ratio. An output turboshaft is in communication with an output of the speed change mechanism.

Claims

1. A turboshaft engine comprising:

a high speed spool connecting a high pressure compressor with a high pressure turbine;

a low speed spool connecting a low pressure compressor with a low pressure turbine;

a speed change mechanism including an input in communication with the low spool and a fixed gear ratio; and

an output turboshaft in communication with an output of the speed change mechanism.

2. The turboshaft engine of claim 1, including a bypass ratio of zero.

3. The turboshaft engine of claim 1, wherein the speed change mechanism is an epicyclic gear train with a constant gear ratio.

4. The turboshaft engine of claim 3, wherein the epicyclic gear train is a star gear system and the output fixed to a ring gear and a carrier is fixed from rotation relative to an engine static structure with a gear ratio of about 1.5 to about 2.5.

5. The turboshaft engine of claim 3, wherein the epicyclic gear train is a planet gear system and the output is fixed to carrier and a ring gear is fixed from rotation relative to an engine static structure with a gear ratio of about 2.5 to 4.0.

6. The turboshaft engine of claim 1, wherein the speed change mechanism is non-epicyclic and includes a gear ratio of about 1.5 to about 2.5.

7. The turboshaft engine of claim 1, wherein an axis of rotation of the output driveshaft is offset from an axis of rotation of the low speed spool.

8. The turboshaft engine of claim 7, wherein the axis of rotation of the output driveshaft is transverse to the axis of rotation of the low speed spool.

9. The turboshaft engine of claim 1, wherein the low pressure compressor includes a pressure ratio of greater than about 1.5 and less than about 6.0 and the high pressure compressor includes a pressure ratio of greater than about 4.0 and less than about 10.0.

10. The turboshaft engine of claim 9, wherein a pressure ratio of the low pressure compressor is greater than about 20 and less than about 40.

11. The turboshaft engine of claim 1, wherein the low speed spool is supported by no more than two bearing systems and the high speed spool is supported by no more than two bearing systems.

12. The turboshaft engine of claim 1, wherein the low speed spool and the high speed spool are supported by at least four bearing systems and no more than ten bearing systems.

13. The turboshaft engine of claim 1, wherein the low pressure turbine includes at least one rotor stage and less than four rotor stages.

14. A method of operating a gas turbine engine comprising the steps of:

rotating a high speed spool including a high pressure compressor and a high pressure turbine at between about 48,000 rpms and about 50,000 rpms;

rotating a low speed spool including a low pressure compressor and a low pressure turbine at about 40,000 rpms;

reducing a rotational speed of the low speed spool by a ratio of about 1.5 to about 4.0 with a speed change mechanism, wherein an input of the speed change mechanism is attached to the low speed spool; and

rotating an output driveshaft with an output of the speed change at a reduced rotational speed.

15. The method of claim 14, wherein the gas turbine engine includes a bypass ratio of zero.

16. The method of claim 14, wherein the speed change mechanism is a star gear system and the output turboshaft fixed to a ring gear and a carrier is fixed from rotation relative to an engine static structure with a gear ratio of about 1.5 to about 2.5.

17. The method of claim 14, wherein the speed change mechanism is a planet gear system and the output turboshaft is fixed to carrier and a ring gear is fixed from rotation relative to an engine static structure with a gear ratio of about 2.5 to 4.0.

18. The method of claim 14, wherein the speed change mechanism is non-epicyclic and includes a gear ratio of about 1.5 to about 2.5.

19. The method of claim 14, wherein the low pressure compressor includes a pressure ratio of greater than about 1.5 and less than about 6.0 and the high pressure compressor includes a pressure ratio of greater than about 4.0 and less than about 10.0.

20. The method of claim 19, wherein a pressure ratio of the low pressure compressor is greater than about 20 and less than about 40.