Impeller shroud with slidable coupling for clearance control in a centrifugal compressor

• US 10,458,429 B2
• Filed: 08/11/2016
• Issued: 10/29/2019
• Est. Priority Date: 05/26/2016
• Status: Active Grant

• Current Assignee: Rolls-Royce Corporation (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce Corporation (Rolls-Royce Holdings Plc)
• Inventors: Nesteroff, Michael, Acker, Jonathan, Crutchfield, Jeffrey, Cooper, Nate, Whitlock, Mark, Ottow, Nathan
• Primary Examiner(s): Rivera, Carlos A
• Assistant Examiner(s): Haghighian, Behnoush
• Application Number:
  US15/234,601
• Publication Number:
  US 20170342996A1
• Time in Patent Office: 1,174 Days
• CPC Class Codes: F01D 11/08 for sealing space between rotor blade tips and stator specially-shaped blade tips therefor F01D5/20
• CPC Class Codes: F01D 11/18 using stator or rotor components with predetermined thermal response, e.g. selective insulation, thermal inertia, differential expansion
• CPC Class Codes: F01D 11/22 by mechanically actuating the stator or rotor components, e.g. moving shroud sections relative to the rotor
• CPC Class Codes: F01D 5/048 Form or construction
• CPC Class Codes: F02C 3/08 the compressor comprising at least one radial stage F02C3/10 takes precedence
• CPC Class Codes: F04D 17/025 comprising axial flow and radial flow stages
• CPC Class Codes: F04D 17/10 for compressing or evacuating
• CPC Class Codes: F04D 27/0246 by varying geometry within the pumps, e.g. by adjusting vanes
• CPC Class Codes: F04D 29/162 of a centrifugal flow wheel
• CPC Class Codes: F04D 29/4206 especially adapted for elastic fluid pumps
• CPC Class Codes: F04D 29/622 Adjusting the clearances between rotary and stationary parts
• CPC Class Codes: F04D 29/624 especially adapted for elastic fluid pumps

Abstract

A system for controlling the clearance distance between an impeller blade tip of a centrifugal compressor and a radially inner surface of an impeller shroud in a turbine engine. The system comprises a high pressure air source, an air piston mounted between an engine casing and the shroud and adapted to receive high pressure air from the high pressure air source, a mounting arm coupling the shroud and air piston, and a slidable coupling adapted to allow axial movement of the shroud and joining the shroud to an axial member.

Claims

1. A compressor shroud assembly in a turbine engine, the compressor shroud assembly comprising:

a static compressor casing;

an actuator mounted to said casing; and

an impeller shroud for encasing a rotatable centrifugal compressor, said impeller shroud coupled at a forward end to said casing by a slidable coupling that maintains an air boundary during the full range of axial movement of said impeller shroud, said impeller shroud mounted proximate an aft end to said actuator, said impeller shroud moving relative to the rotatable centrifugal compressor in an axial direction while maintaining a radial alignment when said actuator is actuated.

2. The compressor shroud assembly of claim 1, further comprising one or more sensors for measuring the clearance gap between said impeller shroud and the rotatable centrifugal compressor, said actuator being actuated or vented in response to the clearance gap measure by the one or more sensors.

3. The compressor shroud assembly of claim 1, further comprising one or more sensors for measuring discharge pressure of the rotatable centrifugal compressor, said actuator being activated in response to the measured pressure.

4. The compressor shroud assembly of claim 1, wherein said actuator is one of a pneumatic, hydraulic, electric, or thermal actuator.

5. The compressor shroud assembly of claim 1, wherein the actuator is an air piston comprising a chamber adapted to receive actuating air and the actuator further comprises an aft extending mounting arm which moves axially while maintaining a radial alignment when said piston is actuated.

6. A compressor shroud assembly in a turbine engine, the compressor shroud assembly comprising:

a static compressor casing;

an actuator mounted to said casing; and

an impeller shroud comprising a static inducer portion coupled to said casing and a dynamically moveable exducer portion coupled at a forward end to said inducer portion by a slidable coupling that maintains an air boundary during the full range of axial movement of said exducer portion, said exducer portion mounted proximate an aft end to said actuator and moving relative to the rotatable centrifugal compressor in an axial direction while maintaining a radial alignment when said actuator is actuated.

7. The compressor shroud assembly of claim 6, further comprising one or more sensors for measuring the clearance gap between said impeller shroud and the rotatable centrifugal compressor, said actuator being actuated or vented in response to the clearance gap measure by the one or more sensors.

8. The compressor shroud assembly of claim 6, further comprising one or more sensors for measuring discharge pressure of the rotatable centrifugal compressor, said actuator being activated in response to the measured pressure.

9. The compressor shroud assembly of claim 6, wherein said actuator is one of a pneumatic, hydraulic, electric, or thermal actuator.

10. The compressor shroud assembly of claim 6, wherein the actuator is an air piston comprising a chamber adapted to receive actuating air and the actuator further comprises an aft extending mounting arm which moves axially while maintaining a radial alignment when said piston is actuated.

11. A method of dynamically changing a clearance gap between a rotatable centrifugal compressor and a shroud encasing the rotatable centrifugal compressor, said method comprising:

mounting an actuator to a static casing;

mounting an impeller shroud to the actuator;

coupling a forward end of said impeller shroud to the casing by a slidable coupling; and

actuating the actuator to thereby move said impeller shroud relative to a rotatable centrifugal compressor, said impeller shroud moving relative to the rotatable centrifugal compressor in an axial direction while maintaining a radial alignment, wherein the slidable coupling between said impeller shroud and said casing maintains an air boundary during the full range of axial movement of said impeller shroud.

12. The method of claim 11 further comprising sensing the clearance gap between the rotatable centrifugal compressor and said impeller shroud and actuating the actuator in response to the sensed clearance gap.

13. The method of claim 11 further comprising sensing the discharge pressure of the rotatable centrifugal compressor and actuating the actuator in response to the sensed discharge pressure.

14. The method of claim 11 wherein the step of actuating the actuator comprises supplying or discharging high pressure air to an air piston to effect axial motion while maintaining a radial alignment of said impeller shroud.