Stator for a gas turbine engine fan

Patent metadata

Field	Value
Publication number	US-10724540-B2
Application number	US-201615370497-A
Country	US
Kind code	B2
Filing date	Dec 6, 2016
Priority date	Dec 6, 2016
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A turbofan engine is disclosed having a bypass duct with an asymmetry in aerodynamic profile caused by a local obstruction in the bypass duct. The engine comprises stator vanes circumferentially spaced-apart around a circumference of the bypass duct. A first group of adjacent stator vanes includes a majority of the plurality of stator vanes and are arranged in a first circumferential sector of the bypass duct and have equal stagger angles. A second group of adjacent stator vanes includes a minority of the plurality of stator vanes and are arranged in a second circumferential sector circumferentially positioned relative to the local obstruction. The stator vanes of the second group have stagger angles different from the stagger angles of the stator vanes of the first group.

First claim

The invention claimed is:

1. A turbofan engine having a fan and a casing defining a bypass duct having an asymmetry in aerodynamic profile caused by a local obstruction in the bypass duct, the local obstruction in use causing an asymmetric back pressure on the fan, the engine comprising: a plurality of stator vanes circumferentially spaced-apart around a circumference of the bypass duct intermediate the fan and the local obstruction, a first group of circumferentially-adjacent stator vanes including a majority of the plurality of stator vanes and a second group of circumferentially-adjacent stator vanes including a minority of the plurality of stator vanes, the stator vanes of the first and second groups having a same axial position along an axis of the engine, the stator vanes of the first group arranged in a first circumferential sector of the bypass duct and having equal stagger angles, the stator vanes of the second group arranged in a second circumferential sector being circumferentially positioned relative to the local obstruction, the stator vanes of the second group having stagger angles different from the stagger angles of the stator vanes of the first group.

2. The turbofan engine as defined in claim 1 , wherein the stator vanes of the second group arranged in the second circumferential sector are aligned with a location of the asymmetric back pressure caused by the local obstruction.

3. The turbofan engine as defined in claim 1 , wherein each stator vane is insertable between a radially inner shroud and a radially outer fan casing of the fan, the stator vanes of the second group being disposed along circumferential segments of the shroud and fan casing corresponding to the second circumferential sector, each circumferential segment having circumferentially spaced-apart mounting slots therein corresponding to positions of the stator vanes, each mounting slot having an orientation angle being equal to the stagger angles of the stator vanes of the second group.

4. The turbofan engine as defined in claim 3 , wherein the stator vanes have identical airfoils.

5. The turbofan engine as defined in claim 1 , wherein the second circumferential sector is circumferentially offset from the local obstruction.

6. The turbofan engine as defined in claim 1 , wherein the stagger angles of the stator vanes of the second group are equal.

7. The turbofan engine as defined in claim 1 , wherein the stagger angles of the stator vanes of the second group are unequal.

8. The turbofan engine as defined in claim 7 , wherein the stator vanes of the second group include peripheral stator vanes and at least one central stator vane disposed between the peripheral stator vanes, the at least one central stator vane having a greater magnitude stagger angle than the stagger angles of the peripheral vanes.

9. The turbofan engine as defined in claim 7 , wherein at least one of the stator vanes of the second group has a stagger angle orienting said stator vane in a first direction, and at least another one of the stator vanes of the second group having a stagger angle orienting said stator vane in a second direction opposite to the first orientation.

10. The turbofan engine as defined in claim 1 , wherein the plurality of stator vanes further comprises a third group of stator vanes having at least two circumferentially-adjacent stator vanes arranged in a third circumferential sector of the bypass duct, the second and the third groups of stator vanes including a minority of the plurality of stator vanes, the stator vanes of the third group being circumferentially aligned with a location of asymmetric back pressure caused by a second local obstruction in the bypass duct, the stator vanes of the third group having stagger angles different from the stagger angles of the stator vanes of the first group.

11. A gas turbine engine, comprising:
a radially outer fan casing and a radially inner shroud, a bypass duct being defined between the fan casing and the shroud;
a fan having a hub and a plurality of fan blades extending radially outwardly from the hub, the fan blades directing air through the bypass duct during operation of the gas turbine engine;
a local obstruction disposed in the bypass duct downstream of the fan blades, the local obstruction encountering the air directed through the bypass duct during operation of the gas turbine engine and generating an asymmetric back pressure on the fan; and
a stator disposed intermediate the fan blades and the local obstruction, the stator having a plurality of stator vanes circumferentially spaced-apart around a circumference of the bypass duct, a first group of circumferentially-adjacent stator vanes including a majority of the plurality of stator vanes and a second group of circumferentially-adjacent stator vanes including a minority of the plurality of stator vanes, the stator vanes of the first and second groups having a same axial position along an axis of the engine, the stator vanes of the first group arranged in a first circumferential sector of the bypass duct and having equal stagger angles, the stator vanes of the second group arranged in a second circumferential sector being circumferentially positioned relative to the local obstruction, the stator vanes of the second group having stagger angles different from the stagger angles of the stator vanes of the first group.

12. The gas turbine engine of claim 11 , wherein the stator vanes of the second group arranged in the second circumferential sector are aligned with a location of the asymmetric back pressure caused by the local obstruction.

13. The gas turbine engine as defined in claim 11 , wherein the stator vanes of the second group are disposed along circumferential segments of the shroud and the fan casing corresponding to the second circumferential sector, each circumferential segment having circumferentially spaced-apart mounting slots therein for receiving the stator vanes of the second group, each mounting slot having an orientation angle being equal to the stagger angles of the stator vanes of the second group.

14. The gas turbine engine as defined in claim 13 , wherein the stator vanes have identical airfoils.

15. The gas turbine engine as defined in claim 11 , wherein the stagger angles of the stator vanes of the second group are unequal.

16. The gas turbine engine as defined in claim 15 , wherein the stator vanes of the second group include peripheral stator vanes and at least one central stator vane disposed between the peripheral stator vanes, the at least one central stator vane having a greater magnitude stagger angle than the stagger angles of the peripheral vanes.

17. A method of assembling a stator for a fan of a gas turbine engine, comprising:
positioning a plurality of stator vanes at a same axial position along an axis of the engine and circumferentially spaced-apart within a bypass duct upstream of a local obstruction within the bypass duct, the local obstruction generating an asymmetric back pressure on the fan;
selecting a group of the plurality of stator vanes, the stator vanes of the group including at least two circumferentially-adjacent stator vanes and less than half of the stator vanes; and
providing the stator vanes of the group with stagger angles different from stagger angles of the remaining stator vanes, the stagger angles of the remaining stator vanes being equal.

18. The method as defined in claim 17 , further comprising determining computationally the asymmetric back pressure to be generated by the local obstruction before selecting the at least two circumferent

Assignees

• Pratt & Whitney Canada

Inventors

• Li Yau-Wai
• Townsend Peter
• Dutton Ronald
• Mason Bernadette

Classifications

• F04D29/666

  by means of rotor construction or layout, e.g. unequal distribution of blades or vanes · CPC title

• F01D9/041

  using blades (F01D5/148 takes precedence) · CPC title

• F02K3/06

  with front fan · CPC title

• F05D2230/60

  Assembly methods · CPC title

• F04D29/542 Primary

  Bladed diffusers (fixing blades to stators F01D9/042) · CPC title