METERED ORIFICE FOR MOTORING OF A GAS TURBINE ENGINE

• US 20180149090A1
• Filed: 11/29/2016
• Published: 05/31/2018
• Est. Priority Date: 11/29/2016
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Maalouf, Fadi S., Bintz, Matthew E.
• Granted Patent: US 10,823,079 B2
• Time in Patent Office: Days
• CPC Class Codes: B64D 27/10 of gas-turbine type jet aircraft B64D27/16
• CPC Class Codes: B64D 31/02 Initiating means
• CPC Class Codes: B64D 31/12 for equalising or synchronising power plants
• CPC Class Codes: F01D 19/02 dependent on temperature of component parts, e.g. of turbine-casing
• CPC Class Codes: F02C 7/26 Starting; Ignition
• CPC Class Codes: F02C 7/27 Fluid drives turbine starters F02C7/277
• CPC Class Codes: F02C 7/277 the starter being a separate turbine
• CPC Class Codes: F05D 2220/323 for aircraft propulsion, e.g. jet engines
• CPC Class Codes: F05D 2260/85 Starting
• CPC Class Codes: F05D 2270/114 by limiting mechanical stresses
• CPC Class Codes: F05D 2270/304 Spool rotational speed

Abstract

A system for motoring a gas turbine engine of an aircraft is provided. The system includes an air turbine starter operable to drive rotation of a starting spool of the gas turbine engine and a starter air valve operable to deliver compressed air to the air turbine starter in response to the starter air valve being open. The system also includes a metered orifice coupled in a bypass configuration around the starter air valve to deliver a reduced amount of the compressed air to the air turbine starter while the starter air valve is closed. The reduced amount of the compressed air delivered to the air turbine starter limits a motoring speed of the gas turbine engine below a resonance speed of the starting spool of the gas turbine engine.

Claims

1. A system for motoring a gas turbine engine of an aircraft, the system comprising:

an air turbine starter operable to drive rotation of a starting spool of the gas turbine engine;

a starter air valve operable to deliver compressed air to the air turbine starter in response to the starter air valve being open; and

a metered orifice coupled in a bypass configuration around the starter air valve to deliver a reduced amount of the compressed air to the air turbine starter while the starter air valve is closed, wherein the reduced amount of the compressed air delivered to the air turbine starter limits a motoring speed of the gas turbine engine below a resonance speed of the starting spool of the gas turbine engine.

2. The system as in claim 1, wherein the compressed air is driven by an auxiliary power unit, a ground cart, or a cross engine bleed.

3. The system as in claim 1, further comprising a controller operable to determine a motoring time to mitigate a bowed rotor condition of the gas turbine engine and initiate opening of the starter air valve after the motoring time expires.

4. The system as in claim 3, wherein the controller is operable to monitor one or more parameters comprising:

an engine speed of the gas turbine engine, a starter speed of the air turbine starter, and a starter air pressure.

5. The system as in claim 4, wherein the controller is operable to request an adjustment to the compressed air source based on the one or more parameters and/or adjust the motoring time based on the one or more parameters.

6. The system as is claim 1, further comprising a variable valve in series with the metered orifice in the bypass configuration around the starter air valve to dynamically control the reduced amount of the compressed air delivered to the air turbine starter.

7. The system as in claim 1, wherein a mitigation monitor determines whether bowed rotor mitigation was successful prior to allowing the motoring speed of the gas turbine engine to reach the resonance speed of the starting spool of the gas turbine engine.

8. A system of an aircraft, the system comprising:

an air turbine starter operable to drive rotation of a starting spool of a gas turbine engine of the aircraft in response to receiving compressed air;

a starter air valve operable to deliver the compressed air to the air turbine starter in response to the starter air valve being open;

a metered orifice coupled in a bypass configuration around the starter air valve to deliver a reduced amount of the compressed air to the air turbine starter while the starter air valve is closed, wherein the reduced amount of the compressed air delivered to the air turbine starter limits a motoring speed of the gas turbine engine below a resonance speed of the starting spool of the gas turbine engine; and

a controller operable to determine a motoring time to mitigate a bowed rotor condition of the gas turbine engine and initiate opening of the starter air valve after the motoring time expires.

9. The system of claim 8, wherein the controller is operable to monitor one or more parameters comprising:

an engine speed of the gas turbine engine, a starter speed of the air turbine starter, and a starter air pressure.

10. The system of claim 9, wherein the controller is operable to request an adjustment to the auxiliary power unit based on the one or more parameters.

11. The system of claim 9, wherein the controller is operable to adjust the motoring time based on the one or more parameters and/or adjust a valve between the starter air valve and the auxiliary power unit based on the one or more parameters.

12. The system of claim 8, further comprising a variable valve in series with the metered orifice in the bypass configuration around the starter air valve to dynamically control the reduced amount of the compressed air delivered to the air turbine starter based on one or more command signals from the controller.

13. The system of claim 8, wherein a mitigation monitor determines whether bowed rotor mitigation was successful prior to allowing the motoring speed of the gas turbine engine to reach the resonance speed of the starting spool of the gas turbine engine.

14. A method for motoring of a gas turbine engine, the method comprising:

determining, by a controller, a motoring time to mitigate a bowed rotor condition of the gas turbine engine;

delivering a reduced amount of compressed air through a metered orifice coupled in a bypass configuration around a starter air valve to an air turbine starter that limits a motoring speed of the gas turbine engine below a resonance speed of a starting spool of the gas turbine engine; and

initiating opening of the starter air valve after the motoring time expires.

15. The method as in claim 14, wherein the compressed air is driven by an auxiliary power unit, a ground cart, or a cross engine bleed.

16. The method as in claim 14, further comprising monitoring one or more parameters comprising:

an engine speed of the gas turbine engine, a starter speed of the air turbine starter, and a starter air pressure.

17. The method as in claim 16, further comprising requesting an adjustment to the compressed air source based on the one or more parameters.

18. The method as in claim 16, further comprising adjusting the motoring time based on the one or more parameters and/or adjusting a valve between the starter air valve and the auxiliary power unit based on the one or more parameters.

19. The method as in claim 14, further comprising adjusting a variable valve in series with the metered orifice in the bypass configuration around the starter air valve to dynamically control the reduced amount of the compressed air delivered to the air turbine starter.

20. The method as in claim 14, further comprising determining whether bowed rotor mitigation was successful prior to allowing the motoring speed of the gas turbine engine to reach the resonance speed of the starting spool of the gas turbine engine.