Managing low pressure turbine maximum speed in a turbofan engine

Patent metadata

Field	Value
Publication number	US-9541028-B2
Application number	US-44212809-A
Country	US
Kind code	B2
Filing date	Oct 12, 2006
Priority date	Oct 12, 2006
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A turbofan engine control system for managing a low pressure turbine speed is provided. The turbofan engine control system includes a low spool having a low pressure turbine that are housed in a core nacelle. The low pressure turbine is adapted to rotate at a speed and includes a maximum design speed. A turbofan is coupled to the low spool. A fan nacelle surrounds the turbofan and core nacelle and provides a bypass flow path. The bypass flow path includes a nozzle exit area. A controller is programmed to command a flow control device adapted to effectively decrease the nozzle exit area in response to a condition. Reducing the nozzle exit area, either physically or otherwise, maintains the speed below the maximum design speed.

First claim

The invention claimed is:

1. A turbofan engine control system for managing a low pressure turbine speed comprising:
a low spool including a low pressure turbine housed in a core nacelle, the low pressure turbine rotatable at a speed and having a maximum design speed;
a turbofan coupled to the low spool;
a fan nacelle surrounding the turbofan and core nacelle and providing a bypass flow path having a nozzle exit area;
a controller programmed to command a flow control device and effectively decrease the nozzle exit area in response to a condition that would result in at least an undesired speed of the low pressure turbine for maintaining the speed below the maximum design speed; and
a gear train interconnecting the low spool and the turbofan for reducing a turbofan speed relative to the speed.

2. The turbofan engine control system according to claim 1 , comprising a high spool rotatable relative to the low spool, the high spool supporting a high pressure compressor and high pressure turbine.

3. The turbofan engine control system according to claim 1 , wherein the flow control device includes an actuator for manipulating a flap in response to the command to physically reduce the nozzle exit area.

4. The turbofan engine control system according to claim 1 , comprising a speed sensor in communication with the controller for detecting the speed, the condition relating to the speed.

5. The turbofan engine control system according to claim 1 , comprising an altitude sensor in communication with the controller for detecting an aircraft altitude, the condition relating to the aircraft altitude.

6. The turbofan engine control system according to claim 1 , comprising a throttle position sensor in communication with the controller for detecting an engine throttle position, the condition relating to the engine throttle position.

7. A method of managing a low pressure turbine speed in a turbofan engine comprising the steps of:
detecting a condition affecting a speed of a low pressure turbine mounted on a low spool;
determining, by a turbofan engine control system, if the condition would cause the speed to reach an undesired speed relative to a maximum design speed for the low pressure turbine;
effectively reducing a nozzle exit area in response to determining the condition would result in at least the undesired speed;
wherein the turbofan engine control system comprises:
the low spool, the low spool including the low pressure turbine housed in a core nacelle, the low pressure turbine rotatable at a speed and having the maximum design speed;
a turbofan coupled to the low spool;
a fan nacelle surrounding the turbofan and core nacelle and providing a bypass flow path having the nozzle exit area;
a controller programmed to command a flow control device and effectively decrease the nozzle exit area in response to a condition that would result in at least the undesired speed of the low pressure turbine for maintaining the speed below the maximum design speed; and
a gear train interconnecting the low spool and the turbofan for reducing a turbofan speed relative to the speed.

8. The method according to claim 7 , comprising the step of detecting an aircraft altitude, the condition including the altitude.

9. The method according to claim 7 , comprising the step of detecting a throttle position, the condition including the throttle position.

10. The method according to claim 7 , comprising the step of detecting the speed.

11. The method according to claim 7 , wherein the step of effectively reducing the nozzle exit area include reducing a physical size of the nozzle exit area.

12. The method according to claim 7 , comprising the step of generating a backpressure on a turbofan after performing the step of effectively reducing the nozzle exit area.

13. The method according to claim 12 , wherein the step of generating backpressure counteracts an increase the speed toward the maximum design speed.

Assignees

• Mcvey William J
• United Technologies Corp

Inventors

• Mcvey William J

Classifications

• F02K3/06

  with front fan · CPC title

• F02K1/15 Primary

  Control or regulation · CPC title

• F05D2270/304

  Spool rotational speed · CPC title

• F02K1/06

  Varying effective area of jet pipe or nozzle (by using fluid jets to influence the jet flow F02K1/30) · CPC title

• F05D2270/021

  to prevent overspeed · CPC title