Bowed rotor start response damping system

• US 10,436,064 B2
• Filed: 02/12/2016
• Issued: 10/08/2019
• Est. Priority Date: 02/12/2016
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Savela, Gregory M.
• Primary Examiner(s): McCalister, William M
• Application Number:
  US15/042,346
• Publication Number:
  US 20170234158A1
• Time in Patent Office: 1,334 Days
• CPC Class Codes: F01D 15/12 Combinations with mechanical gearing driven by multiple engines F01D13/00
• CPC Class Codes: F01D 19/00 Starting of machines or engines; Regulating, controlling, or safety means in connection therewith warming-up before starting F01D25/10; turning or inching gear F01D25/34
• CPC Class Codes: F01D 19/02 dependent on temperature of component parts, e.g. of turbine-casing
• CPC Class Codes: F01D 25/164 Flexible supports; Vibration damping means associated with the bearing
• CPC Class Codes: F01D 25/18 Lubricating arrangements of machines or engines in general F01M
• CPC Class Codes: F01D 5/027 Arrangements for balancing for balancing rotating bodies in general F16F15/32; for compensating unbalance G01M1/36
• CPC Class Codes: F02K 3/06 with front fan
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: F05D 2240/53 Hydrodynamic or hydrostatic bearings
• CPC Class Codes: F05D 2240/60 Shafts
• CPC Class Codes: F05D 2260/98 Lubrication
• CPC Class Codes: F05D 2270/02 to control rotational speed (n)
• CPC Class Codes: F05D 2270/114 by limiting mechanical stresses
• CPC Class Codes: F05D 2270/304 Spool rotational speed
• CPC Class Codes: F16C 2360/23 Gas turbine engines in general F02C
• CPC Class Codes: F16C 27/045 with a fluid film, e.g. squeeze film damping
• CPC Class Codes: F16F 15/0237 involving squeeze-film damping

Abstract

A method of bowed rotor start response damping for a gas turbine engine is provided. A spring rate and a damping characteristic of one or more bearing supports in the gas turbine engine are selectively modified while a shaft of the gas turbine engine rotates below a speed which is adversely affected by a bowed rotor condition of the gas turbine engine.

Claims

1. A method of bowed rotor start response damping for a gas turbine engine, the method comprising:

selectively modifying a spring rate and a damping characteristic of one or more bearing supports in the gas turbine engine by controlling a release of pressurized oil from an accumulator comprising a pressurizing reservoir having a variable volume while a shaft of the gas turbine engine rotates below a rotational speed which adversely affects the gas turbine engine during a bowed rotor condition of the gas turbine engine.

2. The method of claim 1, wherein selectively modifying the spring rate and the damping characteristic of the one or more bearing supports is performed while the shaft of the gas turbine engine rotates at a changing rotational speed that passes through a resonant frequency of the shaft.

3. The method of claim 1, wherein the gas turbine engine comprises a turbofan with a straddle mounted starting spool comprising at least one bearing located aft of at least one turbine disk of the gas turbine engine.

4. The method of claim 1, wherein the gas turbine engine comprises a turbofan.

5. The method of claim 1, wherein selectively modifying the spring rate and the damping characteristic of the one or more bearing supports is performed based on detecting a start indication of the gas turbine engine.

6. The method of claim 5, wherein selectively modifying the spring rate and the damping characteristic of the one or more bearing supports further comprises opening a control valve to urge pressurized oil into a damper of at least one of the one or more bearing supports based on the start indication.

7. The method of claim 6, further comprising selectively closing the control valve to accumulate the pressurized oil in the pressurizing reservoir.

8. A bowed rotor start response damping system for a gas turbine engine, the bowed rotor start response damping system comprising:

an accumulator comprising a pressurizing reservoir having a variable volume; and

an oil supply circuit configured to selectively modify a spring rate and a damping characteristic of one or more bearing supports in the gas turbine engine by controlling a release of pressurized oil from the accumulator while a shaft of the gas turbine engine rotates below a rotational speed which adversely affects the gas turbine engine during a bowed rotor condition of the gas turbine engine.

9. The bowed rotor start response damping system of claim 8, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports is performed while the shaft of the gas turbine engine rotates at a changing rotational speed that passes through a resonant frequency of the shaft.

10. The bowed rotor start response damping system of claim 8, wherein the gas turbine engine comprises a turbofan with a straddle mounted starting spool comprising at least one bearing located aft of at least one turbine disk of the gas turbine engine.

11. The bowed rotor start response damping system of claim 8, wherein the gas turbine engine comprises a geared turbofan.

12. The bowed rotor start response damping system of claim 8, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports are performed based on detecting a start indication of the gas turbine engine.

13. The bowed rotor start response damping system of claim 12, further comprising a control valve, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports further comprises opening the control valve to urge pressurized oil into a damper of at least one of the one or more bearing supports based on the start indication.

14. The bowed rotor start response damping system of claim 13, wherein the control valve is selectively closed to accumulate the pressurized oil in the pressurizing reservoir.

15. A gas turbine engine comprising:

one or more bearing supports;

a shaft supported by one or more bearings of the one or more bearing supports;

an accumulator comprising a pressurizing reservoir having a variable volume; and

an oil supply circuit configured to selectively modify a spring rate and a damping characteristic of the one or more bearing supports by controlling a release of pressurized oil from the accumulator while the shaft rotates below a rotational speed which adversely affects the gas turbine engine during a bowed rotor condition of the gas turbine engine.

16. The gas turbine engine of claim 15, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports is performed while the shaft of the gas turbine engine rotates at a changing rotational speed that passes through a resonant frequency of the shaft.

17. The gas turbine engine of claim 15, wherein the gas turbine engine comprises a turbofan with a straddle mounted starting spool comprising at least one bearing located aft of at least one turbine disk of the gas turbine engine.

18. The gas turbine engine of claim 15, wherein the gas turbine engine comprises a geared turbofan.

19. The gas turbine engine of claim 15, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports are performed based on detecting a start indication of the gas turbine engine.

20. The gas turbine engine of claim 19, further comprising a control valve, wherein selective modification of the spring rate and the damping characteristic of the one or more bearing supports further comprises opening the control valve to urge pressurized oil into a damper of at least one of the one or more bearing supports based on the start indication, and the control valve is selectively closed to accumulate the pressurized oil in the pressurizing reservoir.