Exhaust mixer with offset lobes

Patent metadata

Field	Value
Publication number	US-11085333-B2
Application number	US-201313937587-A
Country	US
Kind code	B2
Filing date	Jul 9, 2013
Priority date	Jul 9, 2013
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

An exhaust mixer for a gas turbine engine where each outer lobe has at the downstream end a circumferential offset in a direction corresponding to that of the swirl component of the flow entering the mixer. The mixer has a crest line having at least a downstream portion curved with respect with respect to a circumferential direction of the mixer and/or a center line at the downstream end tilted with respect to a radial line extending to the tip of the outer lobe to define the circumferential offset. A method of mixing a core flow and a bypass flow surrounding the core flow with an annular mixer is also provided.

First claim

The invention claimed is:

1. An exhaust mixer for a gas turbine engine of the type having an annular bypass passage for channeling air from a fan flow and a main gas path passage, the exhaust mixer being adapted to receive a flow from the main gas path passage having a swirl component in a given direction, the exhaust mixer comprising:
an annular wall defining a central longitudinal axis, the annular wall having opposed upstream and downstream ends and defining a plurality of circumferentially distributed alternating inner and outer lobes, with
each inner lobe protruding into the main gas path passage, and
each outer lobe protruding into the annular bypass passage, each outer lobe having a crest line extending substantially longitudinally through each radially outermost point of the outer lobe and a base defined between spaced apart wall portions of the outer lobe at an upstream end of the crest line, at least a downstream portion of the crest line being curved with respect to a circumferential direction of the mixer and defining a circumferential offset with respect to the base, the downstream end being circumferentially offset from the base by an angle of at most 5 degrees and the circumferential offset being defined in a same direction as that of the swirl component, the circumferential offset adapted to maintain or increase the swirl component, the circumferential offset increasing progressively along the downstream portion of the crest line from the base to a largest circumferential offset at the downstream end.

2. The exhaust mixer as defined in claim 1 , wherein in a cross-section located at the downstream end, each outer lobe defines a center line extending at equal distance from the spaced apart wall portions defining the outer lobe, the center line extending at a non-zero angle with respect to a radial line extending from the longitudinal axis and intersecting the center line at the tip of the outer lobe.

3. The exhaust mixer as defined in claim 2 , wherein each outer lobe is symmetrical about the center line at the downstream end.

4. The exhaust mixer as defined in claim 1 , wherein the circumferential offset at the downstream end is at most 2 degrees.

5. The exhaust mixer as defined in claim 1 , wherein the circumferential offset at the downstream end is at least 0.5 degrees.

6. The exhaust mixer as defined in claim 1 , wherein each crest line is curved along an entire length thereof.

7. The exhaust mixer as defined in claim 1 , wherein each inner lobe defines a valley line extending substantially longitudinally through each radially innermost point of the inner lobe, at least a downstream portion of the valley line being curved with respect to the circumferential direction of the mixer.

8. The exhaust mixer as defined in claim 7 , wherein each crest line and each valley line are curved along an entire length thereof.

9. The exhaust mixer as defined in claim 1 , wherein each inner lobe defines a valley line extending substantially longitudinally through each radially innermost point of the inner lobe, each valley line being coplanar with the longitudinal axis.

10. The exhaust mixer as defined in claim 1 , wherein a path of each crest line corresponds to a circumferential twist about the central longitudinal axis.

11. The exhaust mixer as defined in claim 1 , wherein each inner lobe defines a valley line extending substantially longitudinally through each radially innermost point of the inner lobe, and wherein a path of each crest line corresponds to a pivot about a respective pivot point located on a perimeter of a same imaginary circle extending through each valley line.

12. An exhaust mixer for a gas turbine engine of the type having an annular bypass passage for channeling air from a fan flow and a main gas path passage, the exhaust mixer being adapted to receive a flow from the main gas path passage having a swirl component in a given direction, the exhaust mixer comprising:
an annular wall defining a central longitudinal axis, the annular wall defining a plurality of circumferentially distributed alternating inner and outer lobes, with
each inner lobe protruding into the main gas path passage, and
each outer lobe protruding into the annular bypass passage and defining in a cross-section located at a downstream end thereof a center line extending at equal distance from spaced apart portions of the wall defining the outer lobe, the center line extending at a non-zero angle with respect to a radial line extending from the central longitudinal axis and intersecting the center line at a tip of the outer lobe, the center line being oriented to define a circumferential offset of the outer lobe at the downstream end relative to an upstream end thereof, the circumferential offset being defined in a same direction as that of the swirl component, the circumferential offset adapted to maintain or increase the swirl component,
wherein each outer lobe has a crest line extending substantially longitudinally through each radially outermost point of the outer lobe, the crest line having a downstream end at the downstream end of the mixer and an opposed upstream end, the upstream and downstream ends of the crest line defining a circumferential offset therebetween, the downstream end of the crest line being circumferentially offset from the upstream end of the crest line by an angle of at most 5 degrees, the circumferential offset increasing progressively along the crest line from the upstream end thereof to a largest circumferential offset at the downstream end of the crest line.

13. The exhaust mixer as defined in claim 12 , wherein the center line is straight and the outer lobe is symmetrical about the center line at the downstream end.

14. The exhaust mixer as defined in claim 12 , wherein at least a downstream portion of the crest line is curved with respect to a circumferential direction of the mixer.

15. The exhaust mixer as defined in claim 12 , wherein the circumferential offset at the downstream end is at most 2 degrees.

16. The exhaust mixer as defined in claim 12 , wherein the circumferential offset at the downstream end is at least 0.5 degrees.

17. A method of mixing a core flow having a swirl component and a bypass flow surrounding the core flow with an annular mixer having circumferentially alternating inner and outer lobes, the method comprising:
circulating the bypass flow around the mixer; and
circulating the core flow through the mixer in the outer lobes defining a twist in a same direction as that of the swirl component, wherein each outer lobe has a crest line extending substantially longitudinally and the twist defines a circumferential offset between opposed upstream and downstream ends of the crest line so that the downstream end is circumferentially offset from the upstream end by an angle of at most 5 degrees, the circumferential offset maintaining or increasing the swirl component, the circumferential offset increasing progressively along all points of the crest line, including:
generating pairs of counter rotating radial vortices within the core flow near a tip of the outer lobes; and
with the outer lobes, guiding a downstream transport of the vortices such that adjacent ones of the vortices in a same pair move along different paths defined at different radial distances from a longitudinal axis of the mixer.

18. The method as defined in claim 17 , further comprising, with the outer lobes, guiding the downstream transport of the vortices such that adjacent ones of the vortices in adjacent ones of the outer lobes move along paths defi

Assignees

• Pratt & Whitney Canada
• Pratt & Whiiney Canada Corp

Inventors

• Cunningham Mark
• Marini Remo
• Girgis Sami
• Kameshki Mohammad Reza
• Ramamurthy Raja

Classifications

• F02K1/386 Primary

  mixing devices in the jet pipe, e.g. for mixing primary and secondary flow · CPC title

• F02K1/48 Primary

  Corrugated nozzles · CPC title

• Y02T50/60

  Efficient propulsion technologies, e.g. for aircraft · CPC title

• F05D2250/314

  the axes being inclined in relation to each other · CPC title

• F05D2250/71

  curved · CPC title