U.S. patent application number 10/457938 was filed with the patent office on 2004-04-15 for exhaust mixer and apparatus using same.
Invention is credited to Baker, Von David, Khalid, Syed Arif, Loebig, James Carl, Siefker, Robert G., Vittal, Baily Ramachandra.
Application Number | 20040068981 10/457938 |
Document ID | / |
Family ID | 22356415 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040068981 |
Kind Code |
A1 |
Siefker, Robert G. ; et
al. |
April 15, 2004 |
Exhaust mixer and apparatus using same
Abstract
Disclosed is an exhaust mixer (50) including a passage (54)
extending from an inlet (56) to an outlet (58) that is coincident
with a centerline axis of mixer (50). Several ridges (68) are
circumferentially disposed about the axis and each flare away from
the centerline axis relative to a direction along the centerline
axis from inlet (56) toward outlet (58). Ridges (68) each define a
corresponding one of several inner channels (74) radially disposed
about passage (54) that each intersect passage (54) between inlet
(56) and outlet (58). Several outer channels (84) are also radially
disposed about passage (54) and are each positioned between a
corresponding pair of inner channels (74). Ridges are each shaped
to turn inner channels (74 and outer channels (84) about the axis
as ridges (68) extend along the indicated direction. Inner channels
(74) diverge away from the axis and one another in this direction
while outer channels (84) converge toward the axis and one another
in this direction.
Inventors: |
Siefker, Robert G.;
(Greenwood, IN) ; Vittal, Baily Ramachandra;
(Carmel, IN) ; Baker, Von David; (Indianapolis,
IN) ; Khalid, Syed Arif; (Indianapolis, IN) ;
Loebig, James Carl; (Indianapolis, IN) |
Correspondence
Address: |
Woodard, Emhardt, Moriarty, McNett & Henry LLP
Bank One Center/Tower
Suite 3700
111 Monument Circle
Indianapolis
IN
46204-5137
US
|
Family ID: |
22356415 |
Appl. No.: |
10/457938 |
Filed: |
June 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10457938 |
Jun 10, 2003 |
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09551728 |
Apr 18, 2000 |
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6606854 |
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09551728 |
Apr 18, 2000 |
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PCT/US00/00098 |
Jan 4, 2000 |
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60114623 |
Jan 4, 1999 |
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Current U.S.
Class: |
60/262 |
Current CPC
Class: |
F02K 1/48 20130101; Y02T
50/60 20130101; Y02T 50/672 20130101; B63H 21/34 20130101; F02K
1/386 20130101; F05D 2250/25 20130101; B63G 13/02 20130101 |
Class at
Publication: |
060/262 |
International
Class: |
F02K 001/38 |
Claims
What is claimed is:
1. An exhaust mixer, comprising: a passage extending from an inlet
to an outlet to convey an exhaust flow therethrough, said passage
extending along a centerline axis of the mixer; several lobes
circumferentially disposed about the axis and each defining a
corresponding one of several inner channels, said inner channels
each intersecting at least one other of said inner channels between
said inlet and said outlet; and wherein said lobes are each shaped
to turn said inner channels about said axis to block viewing of
said inlet through said lobes from a view plane perpendicular to
said axis and downstream of said outlet.
2. The exhaust mixer of claim 1, wherein inlet has a generally
circular cross section along said axis and said outlet has a
generally symmetric, serpentine contour about said axis.
3. The exhaust mixer of claim 1, wherein said mixer further
includes several outer channels each positioned between a
correspond pair of said inner channels, said lobes each include a
different pair of a number of walls radially disposed about said
axis, and said walls each separate a respective one of said inner
channels from a respective one of said outer channels.
4. The exhaust mixer of claim 3, wherein said inner channels and
said outer channels each correspond to a different one of a number
of sectors of a cross section taken along said axis, said sectors
each subtending an angle less than or equal to 45 degrees.
5. The exhaust mixer of claim 1, further comprising several fins
each projecting into said passage from an inner surface bounding
said inner channels or said passage.
6. The exhaust mixer of claim 5, wherein at least one of said fins
is in the form of a vane defining a passageway in fluid
communication with a corresponding one of said outer channels.
7. The exhaust mixer of claim 1, wherein said lobes each have a
helical shape about said axis to rotate each of said inner channels
at least 15 degrees about said axis, and said lobes each flare away
from said axis as said lobes each advance in a direction from said
inlet to toward said outlet along said axis.
8. The exhaust mixer of claim 1, wherein said lobes each include a
pair of confronting walls with said corresponding one of said inner
channels therebetween, a first one of said pair of confronting
walls extending farther along said axis at said outlet than a
second one of said pair of confronting walls for each of said
lobes.
9. An apparatus, comprising: a gas turbine engine; and an exhaust
mixer coupled to said engine along an axis, said mixer including
several outward ridges radially projecting away from said axis,
said ridges each defining one of a number of inner channels
intersecting at least one other of said inner channels within said
mixer, said ridges each being shaped to turn said inner channels
about said axis.
10. The apparatus of claim 9, further comprising: an aircraft, said
engine being coupled to said aircraft and being configured to
propel said aircraft; and a duct coupled to said engine to expel a
exhaust flow from said engine during engine operation, said mixer
being positioned within said duct.
11. The apparatus of claim 9, wherein said mixer includes a passage
extending from an inlet to receive said exhaust flow to an outlet
to discharge said exhaust flow, said inner channels cooperate with
said passage to direct the exhaust flow, said mixer defines a
number of outer channels each provided between a corresponding pair
of said ridges, and said outer channels are operable to direct
cooling air to mix with the exhaust flow at said outlet when said
engine is operating.
12. The apparatus of claim 9, wherein said inner channels each have
a cross-sectional contour taken along said axis corresponding to an
annular sector shape.
13. The apparatus of claim 9, further comprising a number of outer
channels radially disposed about said axis, said outer channels
each being positioned between a corresponding pair of said ridges,
said ridges each including a different pair of a number of walls
radially disposed about said axis, said walls each separating a
respective one of said inner channels from a respective one of said
outer channels.
14. The apparatus of claim 9, wherein said inner channels rotate
about said axis at least 15 degrees as said ridges extend along
said axis.
15. The apparatus of claim 9, further comprising a plurality of
fins extending into said passage.
16. The apparatus of claim 9, wherein said ridges each include a
pair of confronting walls with a corresponding one of said inner
channels therebetween, a first one of said pair of confronting
walls extending farther along said axis than a second one of said
pair of confronting walls for each of said ridges.
17. The apparatus of claim 9, wherein said ridges are each have a
helical shape about said axis to twist each of said inner channels
at least about 20 degrees about said axis as said ridges extend
along said axis, said ridges each include a different pair of a
number of walls radially disposed about said axis, said walls each
separate a respective one of said inner channels from a different
one of a number of outer channels, said inner channels and said
outer channels each correspond to a different one of a number of
sectors of an imaginary circle with a center coincident with said
axis, and said sectors each subtend an angle less than or equal to
about 30 degrees.
18. An apparatus, comprising: an engine operable to discharge an
exhaust flow and a mixer coupled to said engine along an axis to
mix the exhaust flow with cooling air, said mixer including: a
passage extending from an inlet to an outlet along a centerline
axis of said mixer; and a number of inner chutes circumferentially
disposed about said passage, said inner chutes each opening into
said passage and being shaped to turn about said axis to block
viewing of said engine through said inner chutes.
19. The apparatus of claim 18, wherein inlet has a generally
circular cross section along said axis and said outlet has a
generally symmetric, serpentine contour about said axis.
20. The apparatus of claim 18, wherein said mixer further includes
several outer chutes each positioned between a correspond pair of
said inner chutes.
21. The apparatus of claim 20, further comprising a several fins
each projecting into said passage from an inner surface bounding
said inner chutes or said passage.
22. The apparatus of claim 21, wherein one or more of said fins are
in the form of a vane defining a passageway in fluid communication
with a corresponding one of said outer channels.
23. The apparatus of claim 18, further comprising a number of wall
portions each extending a corresponding one of said inner chutes to
block said corresponding one of said inner chutes from view at a
point downstream from said outlet along a line of sight parallel to
said axis.
24. An apparatus, comprising: a gas turbine engine operable to
produce an exhaust flow; a conduit coupled to said engine along an
axis to mix the exhaust flow with cooling air, said conduit
including a passage and a number of lobes each defining a
corresponding one of several inner channels circumferentially
disposed about said axis, said lobes each being shaped to turn a
corresponding one of said inner channels about said axis as said
corresponding one of said inner channels advances along said axis;
and a number of fins each extending into said passage from said
conduit and converging with one or more other of said fins as said
axis is approached.
25. The apparatus of claim 24, wherein said fins are each shaped to
twist about said axis as said fins each extend along said axis.
26. The apparatus of claim 24, wherein said conduit defines a
number of outer channels each positioned between a corresponding
pair of said inner channels.
27. The apparatus of claim 26, wherein said passage includes an
inlet to receive the exhaust flow and an outlet to discharge the
exhaust flow, said outer channels turn about said axis with said
inner channels, and said lobes each flare outward as said lobes
each advance along said axis from said inlet to said outlet.
28. The apparatus of claim 24, wherein one or more of said fins
each include a passageway in fluid communication with a
corresponding one of said outer channels.
29. The apparatus of claim 28, wherein said engine includes a
centerbody extending into said mixer through said inlet, and said
passageway of each of said one or more fins is in fluid
communication with an opening into said centerbody.
30. The apparatus of claim 24, wherein said inner channels twist
about said axis to block view of said engine through said lobes
from a view plane perpendicular to said axis, and downstream of
said outlet and said fins are arranged in a spiral pattern at said
outlet to at least partially block view through said passage from
said view plane.
31. The apparatus of claim 24, further comprising an aircraft, said
engine being coupled to said aircraft and being configured to
propel said aircraft.
32. The apparatus of claim 24, wherein said lobes each include a
different pair of a number of walls radially disposed about said
axis, said walls each separate a respective one of said inner
channels from a respective one of said outer channels, and a first
one of said pair of confronting walls extends farther along said
axis than a second one of said pair of confronting walls for each
of said lobes.
33. The apparatus of claim 24, wherein said fins are visible
through an outlet of said passage.
34. An apparatus, comprising: a gas turbine engine operable to
produce an exhaust flow and a mixer coupled to said engine along an
axis to mix the exhaust flow with cooling air, said mixer
including: a passage positioned along said axis to convey said
exhaust flow therethrough; several inner chutes circumferentially
disposed about said passage; several outer chutes circumferentially
disposed about said passage, said outer chutes each being
positioned between a respective pair of said inner chutes; and a
number of vanes each extending into said passage, one or more of
said vanes each including a passageway in fluid communication with
a corresponding one of said outer chutes.
35. The apparatus of claim 34, wherein said passage includes an
inlet opposite said outlet along said axis, said inner chutes each
turn about said axis as said inner chutes each extend along said
axis, and said inner chutes each open into said passage.
36. The apparatus of claim 34, further comprising an aircraft, said
engine being coupled to said aircraft and being configured to
propel said aircraft.
37. The apparatus of claim 34, wherein said inner chutes are each
defined by a corresponding one of a number of lobes radially
disposed about said passage, said lobes each include a different
pair of a number of walls radially disposed about said axis.
38. The apparatus of claim 37, wherein said vanes are radially
disposed about said axis.
39. The apparatus of claim 37, wherein said lobes each have a
helical shape rotating at least 15 degrees about said axis as said
lobes each extend along said axis.
40. The apparatus of claim 34, wherein said engine includes a
centerbody extending into said mixer, and said passageway of each
of said one or more vanes is in fluid communication with a plenum
in said centerbody.
41. An apparatus, comprising: a gas turbine engine operable to
produce an exhaust flow; a conduit coupled to said engine along an
axis to mix the exhaust flow with cooling air, said conduit
including a passage and a number of lobes circumferentially
disposed about said passage; and a number of fins each extending
into said passage from said conduit and being shaped to turn about
said axis as said fins each advance along said axis.
42. The apparatus of claim 41, wherein said lobes each include a
corresponding one of a number of inner channels.
43. The apparatus of claim 42, wherein said conduit defines a
number of outer channels each positioned between a corresponding
pair of said inner channels.
44. The apparatus of claim 42, wherein said lobes are each shaped
to turn said inner channels with said fins at least 15 degrees
about said axis.
45. The apparatus of claim 41 further comprising an aircraft, said
engine being coupled to said aircraft and being configured to
propel said aircraft.
46. The apparatus of claim 41, wherein said fins each extend
radially relative to said axis and are visible through a discharge
outlet of said passage.
47. An apparatus, comprising: a gas turbine engine and a mixer
coupled to said engine along an axis to mix cooling air with an
exhaust flow produced during engine operation, said mixer
including: an inlet and an outlet opposite said inlet along said
axis; a number of lobes radially disposed about said axis, said
lobes each turning about said axis between said inlet and said
outlet as said lobes each extend along said axis, said lobes
including a number of wall portions at said outlet, said wall
portions each extending a first side of a respective one of said
lobes past a second side of said respective one of said lobes along
said axis to reduce thermal signature of the apparatus.
48. The apparatus of claim 47, wherein said wall portions each at
least partially obstruct view of an inner surface of said second
one of said sides for said respective one of said lobes from a
plane perpendicular to said axis and downstream from said
outlet.
49. The apparatus of claim 47, wherein said wall portions are each
shaped to define a coanda surface.
50. The apparatus of claim 47, wherein said wall portions each
block view of said second side for said respective one of said
lobes from a plane perpendicular to said axis and downstream from
said outlet.
51. The apparatus of claim 47, wherein said lobes each include one
of a number of inner channels radially disposed about said axis
between said inlet and said outlet.
52. The apparatus of claim 51, wherein said mixer includes a number
of outer channels each positioned between a corresponding pair of
inner channels, said inner channels and said outer channels each
twisting about said axis to block a line of sight view of said
engine from said outlet through said inner channels.
53. The apparatus of claim 47, further comprising: an aircraft,
said engine being coupled to said aircraft and being configured to
propel said aircraft; and a duct coupled to said engine to
discharge the exhaust flow from said engine during engine
operation, said mixer being positioned within said duct.
54. An apparatus, comprising: a gas turbine engine and a mixer
coupled to said engine along an axis to mix cooling air with an
exhaust flow produced during engine operation, said mixer
including: an inlet and an outlet opposite said inlet along said
axis; a number of inner chutes radially disposed about said axis,
said inner chutes each turning about said axis as said inner chutes
each extend along said axis; and a number of wall portions at said
outlet, said wall portions each extending from a corresponding one
of said inner chutes to block view of said corresponding one of
said inner chutes from downstream of said outlet along a line of
sight parallel to said axis.
55. The apparatus of claim 54, wherein said wall portions are each
shaped to define a coanda surface.
56. The apparatus of claim 54, wherein said mixer includes a
passage extending through said mixer from said inlet to said
outlet, and said inner chutes each open into said passage between
said inlet and said outlet.
57. The apparatus of claim 54, wherein said wall portions each
cooperate with said corresponding one of said inner chutes to block
view of said engine through said inner chutes.
58. The apparatus of claim 54, further comprising: an aircraft,
said engine being coupled to said aircraft and being configured to
propel said aircraft; and a duct coupled to said engine to
discharge the exhaust flow from said engine during engine
operation, said mixer being positioned within said duct.
59. An apparatus, comprising: a gas turbine engine and a mixer
coupled to said engine along an axis to mix cooling air with an
exhaust flow produced during engine operation, said mixer
including: an inlet and an outlet opposite said inlet along said
axis; a number of lobes radially disposed about said axis, said
lobes each turning about said axis between said inlet and said
outlet as said lobes each extend along said axis, said lobes each
including a respective one of a number of first walls opposite a
respective one a number of second walls, said respective one of
said first walls hiding said respective one of said second walls
from view along a view plane perpendicular to said axis and
downstream of said outlet.
60. The apparatus of claim 59, wherein said first walls are each
shaped to define a coanda surface.
61. The apparatus of claim 59, wherein said lobes each include one
of a number of inner channels and said mixer includes a passage
extending through said mixer from said inlet to said outlet.
62. The apparatus of claim 61, wherein said mixer includes a number
of outer channels each positioned between a corresponding pair of
inner channels, said inner channels and said outer channels each
twisting about said axis to block a line of sight view of said
engine from said outlet through said inner channels.
63. The apparatus of claim 59, further comprising: an aircraft,
said engine being coupled to said aircraft and being configured to
propel said aircraft; and a duct coupled to said engine to expel
the exhaust flow from said engine during engine operation, said
mixer being positioned within said duct.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S.
Provisional Patent Application serial No. 60/114,623 filed 4 Jan.
1999, which is hereby incorporated by reference.
BACKGROUND
[0002] The present invention relates to exhaust mixers, and more
particularly, but not exclusively, relates to an exhaust mixer for
a gas turbine engine that reduces the visibility of hot parts.
[0003] It is often desirable to mix exhaust from a gas turbine
engine with cooler air. Such mixing is often utilized to reduce the
noise level generated by gas turbine engines especially those used
to propel aircraft. Several devices to facilitate mixing have been
developed that are placed in the path of exhaust exiting the
engine; however, in many applications, these devices leave room for
improvement.
[0004] Furthermore, in certain applications, it is desirable to
reduce visibility of hot parts of the engine through the mixing
device. Alternatively or additionally, it may also be desirable to
block view of the hot regions of the device itself.
[0005] Accordingly, there is a demand for further contributions in
this area of technology.
SUMMARY
[0006] One form of the present invention is a mixer with improved
line-of-sight blockage.
[0007] In an alternative form, an improved mixer has a number of
lobes each shaped to block at least a portion of the hot inner
surface of the mixer or hot parts of the exhaust portion of an
engine coupled to the mixer. Preferably, the lobes are curved in a
pattern selected to provide a desired degree of blockage. More
preferably, the lobes generally twist about a reference axis
corresponding to the mixer, such as the mixer's centerline axis.
However, in other embodiments of the present invention, the lobes
may be shaped or oriented differently.
[0008] In another form, a mixer includes a number of radial lobes
that each terminate in a radial end wall or fin. The mixer may
include lobes that twist about an axis corresponding to the
direction of working fluid flow through the mixer. The walls may
include a curved edge to direct working fluid towards a centerline
axis of the mixer. However, in other embodiments, the walls may be
shaped differently in accordance with the present invention.
[0009] In still another form, a mixer is provided that includes a
number of radially oriented troughs and a number of structures that
each extend from a corresponding one of the troughs toward the
centerline of the mixer. These structures may be in the form of
fins or vanes that at least partially block hot parts. The mixer
may alternatively or additionally include a curved or twisting
pattern of the troughs relative to a reference axis to enhance
line-of-sight blockage. For embodiments of the present invention
including the structures extending toward the center of the mixer,
these structures may also be arranged in a curved or twisted
pattern.
[0010] In a further form, a multilobed mixer includes a number of
hollow radial vanes that extend from troughs between adjacent pairs
of the mixer lobes toward the center of the mixer to provide
cooling fluid. The cooling fluid may be utilized to cool a
centerbody of an associated engine. The mixer may additionally or
alternatively include a curved or twisting pattern of lobes
relative to a reference axis to enhance line-of-sight blockage. For
embodiments of the present invention that include the vanes, the
vanes may also be oriented or shaped to follow a curved or twisted
pattern.
[0011] In other forms of the present invention, a mixer according
to the present invention may be coupled to an engine used to propel
a vehicle. The vehicle may be an aircraft with the engine being of
the gas turbine variety. In other embodiments, the mixer of the
present invention is employed with a different vehicle type, such a
land vehicle or a vessel that travels on or through the water.
Also, a mixer according to the present invention may be utilized
with any engine type as would occur to those skilled in the
art.
[0012] Further forms, embodiments, objects, features, advantages,
benefits, and aspects of the present invention shall become
apparent from the drawings and description provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a side view of a first embodiment of the present
invention.
[0014] FIG. 2 is a partial sectional, side view of the exhaust
mixing system shown in FIG. 1.
[0015] FIG. 3 is an end, elevational view of the exhaust mixer
shown in FIG. 2.
[0016] FIG. 4 is a top left, isometric view of the exhaust mixer
shown in FIG. 2.
[0017] FIG. 5 is a top left, perspective view of the exhaust mixer
shown in FIG. 2 along a different line of sight than FIG. 4.
[0018] FIG. 5A is a schematic representation of the rotation about
axis F of path P shown in FIG. 5.
[0019] FIG. 6 is a side, elevational view of an exhaust mixer of a
second embodiment of the present invention.
[0020] FIG. 7 is an end, elevational view of the embodiment of FIG.
6.
[0021] FIG. 8 is a top left, isometric view of the embodiment of
FIG. 6.
[0022] FIG. 9 is a side, elevational view of an exhaust mixer of a
third embodiment of the present invention.
[0023] FIG. 10 is an end, elevational view of the embodiment of
FIG. 9.
[0024] FIG. 11 is a top left, isometric view of the embodiment of
FIG. 9.
[0025] FIG. 12 is an end, elevational view of an exhaust mixer of a
fourth embodiment of the present invention.
[0026] FIG. 13 is a partial sectional, end view of the embodiment
of FIG. 12.
[0027] FIG. 14 is a top left, isometric view of the embodiment of
FIG. 12.
[0028] FIG. 15 is an end, elevational view of an exhaust mixer of a
fifth embodiment of the present invention.
[0029] FIG. 16 is a partial sectional, end view of the embodiment
of FIG. 15.
[0030] FIG. 17 is a top left, isometric view of the embodiment of
FIG. 15.
[0031] FIG. 18 is an end, elevational view of an exhaust mixer of a
sixth embodiment of the present invention.
[0032] FIG. 19 is a partial sectional, end view of the embodiment
of FIG. 18.
[0033] FIG. 20 is a top left, isometric view of the embodiment of
FIG. 18.
DESCRIPTION OF SELECTED EMBODIMENTS
[0034] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to various
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended. Any alterations and further modifications in the
described embodiments, and any further applications of the
principles of the invention as described herein are contemplated as
would normally occur to one skilled in the art to which the
invention relates.
[0035] One embodiment of the present invention is shown in FIG. 1
as aircraft 20. Aircraft 20 includes fuselage 22 and wing 24.
Turboprop 30 is mounted to wing 24 and includes gas turbine engine
32 with intake 34. Exhaust produced by engine 32 flows along an
exhaust pathway and exits at discharge 36. Mixing system 40 is
provided along this exhaust pathway. Mixing system 40 includes duct
42 defining discharge 36, and mixer 50 (shown in phantom)
positioned in duct 42.
[0036] Referring additionally to FIG. 2, a partial sectional, side
view of mixing system 40 is illustrated. Mixer 50 includes conduit
52 positioned in duct 42 about centerline axis F. Conduit 52
includes passage 54 extending from inlet 56 defined by conduit end
portion 57 to outlet 58 defined by conduit end portion 59. Inlet 56
is positioned opposite outlet 58 along axis F, and at least a
portion of passage 54 is coincident with axis F, such that axis F
passes through the center of inlet 56 and outlet 58. Mixer 50 is
coupled to gas turbine engine 32 along axis F. Gas turbine engine
32 is partially shown in FIG. 2 with turbine 33 having blades 35
positioned in annular working fluid passage 37. Passage 37 is
defined by engine casing 38. Casing 38 is sized to fit within duct
42 and is coupled to mixer 50 to align inlet 56 with passage 37.
Engine 32 is extended by centerbody 39 that enters mixer 50 through
inlet 56, and terminates in conduit 52 of mixer 50.
[0037] Gas turbine engine 32 operates in the standard manner,
receiving air through intake 34 for pressurization by one or more
compressors rotating about axis F (not shown). At least a portion
of this pressurized air is mixed with fuel to provide a fuel charge
that is combusted to release energy in the form of hot, expanding
gases. These combustion gases impinge on one or more turbines, such
as turbine 33 shown in FIG. 2, causing the one or more turbines to
rotate about axis F. The mechanical power provided by turbine
rotation is used to do work, such as propel aircraft 20. Also,
rotation of each of the one or more compressors is typically
maintained by a rotatable coupling to a corresponding turbine;
thereby continuing the supply of pressurized air to sustain
combustion.
[0038] It should be understood that gas turbine engine 32 may
include a number of other components that are not shown to enhance
clarity. Further, any compressors and/or turbines of gas turbine
engine 32 may be of a single or multi-stage variety. Alternatively
or additionally, gas turbine engine 32 may include multiple spools
each comprised of a compressor rotatably coupled by a shaft to a
turbine. In one common "dual spool" configuration, the shafts of
two spools are arranged concentric to one another to
correspondingly provide a low pressure or fan stage compressor
upstream of a high pressure compressor, with a corresponding pair
of turbines to drive the low and high pressure stages. In another
configuration, gas turbine engine 32 also includes a turbine that
is not coupled to a compressor and accordingly is capable of
rotating freely relative to any compressor. This free turbine is
typically arranged to turn a shaft for delivering mechanical power,
and is commonly used in turboprop and helicopter applications.
[0039] In still another embodiment, gas turbine engine 32 is
arranged to propel a vehicle with the thrust produced by
discharging a working fluid jet through a nozzle. Duct 42 can be
arranged to provide a suitable nozzle for such embodiments. Indeed,
in other embodiments of the present invention, mixing system 40 is
used with different varieties of engines either in addition or as
an alternative to the gas turbine type. These different types may
include pulse detonation engines, wave rotor engines, ram jets,
internal combustion engines of the reciprocating piston variety,
internal combustion engines of the intermittent Spark Ignition (SI)
or Compression Ignition (CI) variety, and/or hybrid combinations of
such engine types, just to name a few.
[0040] During engine operation, inlet 56 of mixer 50 is arranged to
receive hot exhaust gases for intermixing with relatively cooler
gases before being discharged through discharge 36. In FIG. 2, the
hot exhaust flow from engine 32 is designated by arrows EF. Inlet
56 of passage 54 is in fluid communication with passage 37 to
receive exhaust flow EF. An outside stream of cooling fluid, as
designated in FIG. 2 by arrows CF, flows between duct 42 and
conduit 52 of mixer 50 to be mixed with exhaust flow EF at outlet
58. Typically, this cooling fluid is air from an outside inlet,
compressor stage, or fan stage of engine 32.
[0041] Referring further to the end elevational view of FIG. 3; the
top left isometric view of FIG. 4; and the top left perspective
view of FIG. 5; it should be understood that the shape of mixer 50
gradually transitions along axis F from a generally circular
opening at inlet 56 to a multifluted structure at outlet 58 to aide
in the mixing. To provide contrasting views, FIGS. 3 and 4
illustrate centerbody 39 in relation to mixer 50, while FIG. 5 does
not. Axis F is perpendicular to the view plane of FIG. 3 and is
represented by cross hairs. At outlet 58, passage 54 terminates
with a central aperture 60 surrounded by a number of lobes 62 (only
a few of which are specifically designated to preserve clarity) as
best seen in FIG. 3. Aperture 60 corresponds to a generally
circular cross-section along axis F that is smaller in area than
the circular cross-section along axis F at the circular opening of
inlet 56.
[0042] Lobes 62 are radially disposed about axis F and gradually
extend away from axis F with respect to a direction of travel along
axis F from inlet 56 to outlet 58. This direction is designated as
"downstream" and the opposite direction along axis F is designated
"upstream" in correspondence with the direction gas is discharged
from system 40 through discharge 36. Under this convention, a first
position along axis F is downstream relative to a second position
along axis F if the first position if farther along axis F in the
downstream direction. Also, for this example, the second position
is upstream relative to the first position because it is farther
along axis F in the upstream direction.
[0043] Each lobe 62 is circumferentially positioned about passage
54 between a corresponding pair of adjacent lobes 62 to form a
serpentine contour 63 about axis F. Individually, each one of lobes
62 is formed between two radii originating from axis F and
intersecting points of mixer 50 that are relatively closest to axis
F (minimum radius points) for the illustrated embodiment. In FIG.
3, a representative lobe 62 is designated between the radial end
points R1 and R2 each corresponding to a radius originating from
axis F.
[0044] As specifically designated for lobe 62 between points R1 and
R2 in FIG. 3, lobes 62 each include a corresponding pair of
confronting walls 64 radially extending from axis F. Each pair of
confronting walls 64 are coupled by a curved dome 66 to
collectively form a corresponding ridge 68 with radial apex 70. As
lobes 62 flare away from axis F in the downstream direction, a
number of troughs 72 are formed, each gradually deepening between a
corresponding adjacent pair of lobes 62. Individually, each one of
troughs 72 is formed between two radii originating from axis F and
intersecting points of mixer 50 that are relatively farthest away
form axis F (maximum radius points), which, for the illustrated
embodiment, are coincident with the apices 70 of the adjacent pair
of lobes 62. In FIG. 3, a representative trough 72 is designated
between the radial points R3 and R4. The shading dots in FIG. 2
schematically represent receding regions corresponding to troughs
72.
[0045] Each lobe 62 includes an inner channel 74 formed between the
corresponding pair of walls 64. Each inner channel 74 intersects
the other inner channels 74 via passage 54 at a necked-down region
75 as illustrated for the lobe between points R1 and R2. As each
lobe 62 flares away from axis F in the downstream direction, inner
channels diverge away from one another and axis F. Correspondingly,
lobes 62 each provide one of a number of divergent, inner chutes 76
that open into passage 54 to direct exhaust flow EF as it passes
through mixer 50.
[0046] Each trough 72 includes an outer channel 84 formed between
walls 64 of adjacent lobes 62. Each outer channel 84 is positioned
between an adjacent pair of inner channels 74. Further, outer
channels 84 are arranged to alternate with inner channels 74 about
axis F. As each trough 72 advances in the downstream direction
along axis F, outer channels 84 converge toward one another and
axis F. Correspondingly, troughs 72 each provide one of a number of
convergent outer chutes 86 to direct cooling fluid CF flowing
between duct 42 and conduit 52 of mixer 50.
[0047] It should be understood that walls 64 are arranged to
separate inner channels 74 from outer channels 84 and
correspondingly provide alternating inner chutes 76 and outer
chutes 86. Thus, with respect to a cross section along axis F taken
at outlet 58, walls 64 correspond to a number of annular sectors
centered about axis F. Each lobe 62 and trough 72 belong to a
different one of these sectors. In one preferred embodiment, these
sectors each subtend an angle less than or equal to 90 degrees and
lobes 62 number at least 2. In a more preferred embodiment, these
sectors each subtend an angle less than or equal to 45 degrees and
lobes 62 number at least 4. In a still more preferred embodiment,
these sectors each subtend an angle of less than or equal to 30
degrees and lobes 62 number at least 6. In a most preferred
embodiment, these sectors each subtend an angle of less than or
equal to 15 degrees and lobes 62 number at least 12. In FIG. 3 ,
representative sectors S1 and S2 are illustrated corresponding to
one of lobes 62 and an adjacent trough 72, respectively. Sectors S1
and S2 are defined by radii rs1, rs2, rs3.
[0048] When traveling along axis F from inlet 56 to outlet 58,
lobes 62 and troughs 72 gradually twist about axis F.
Correspondingly, lobes 62 and troughs 72 each have a curving spiral
or helical shape about axis F. Also, inner channels 74 and outer
channels 84 are turned about axis F, following a corresponding
spiral or helical path. It should be understood that in the
illustrated embodiment, lobes 62, troughs 72, inner channels 74,
outer channels 84, inner chutes 76, and outer chutes 86 each follow
a corresponding spiral path that rotates about axis F for less than
a complete revolution. The twisted shape of inner channels 74
increases the line-of-sight blockage of hot parts of engine 32
adjacent inlet 56 through outlet 58. The degree of twisting is
preferably selected to provide a desired balance between the degree
of blockage required and the cost/efficiency impact the twist may
have, if any. For this illustrated embodiment, the shape of lobes
62 turn inner channels 74 about axis F to block view of inlet 56
through lobes 62 from a line of sight parallel to axis F that
originates downstream of outlet 58.
[0049] The amount of rotation may be expressed in units of degrees
that a radius rotates about axis F as it traces one of these paths
along axis F in the downstream direction. One representative path P
extending from point TR1 to point TR2 is illustrated along apex 70
of a corresponding lobe 62 in FIG. 5. In FIG. 5A, points TR1 and
TR2 correspond to extreme positions of a radius tracing path P from
inlet 56 to outlet 58. Point TR1 corresponds to an end of path P at
inlet 56 and point TR2 corresponds to an end of path P at outlet
58. The angular separation between radii originating at axis F and
terminating at points TR1 and TR2, respectively, is represented by
angle A. Correspondingly, angle A also represents the amount of
rotation of path P about axis F. In one preferred embodiment, angle
A is at least 15 degrees. In a more preferred embodiment, angle A
is at least 25 degrees. In a most preferred embodiment having
twelve circumferentially spaced apart lobes 62 and troughs 72 in a
generally symmetric arrangement about axis F, angle A is about 27
to about 30 degrees. In other embodiments, mixer 50 may be arranged
to provide an amount of twist about axis F greater than 30 degrees
for any of lobes 62, troughs 72, inner channels 74, inner chutes
76, outer channels 84, and/or outer chutes 86 up to and including
one or more revolutions about axis F. Notably, mixer 50 may utilize
a counter-twist to minimize any efficiency losses that might arise
and still provide the desired blockage.
[0050] Mixer 150 of another embodiment of the present invention is
illustrated in the side, elevational view of FIG. 6; the end,
elevational view of FIG. 7; and the top left, isometric view of
FIG. 8. Mixer 150 includes duct 152 with passage 154 extending from
inlet 156 to outlet 158 in a manner analogous to mixer 50.
Furthermore, mixer 150 can be interchanged with mixer 50 in mixing
system 40 of aircraft 20 described in connection with FIGS. 1-5.
Mixer 150 includes lobes 162 each defined by a corresponding pair
of side walls 164 radially extending from axis F and coupled
together by a corresponding dome 166 to form a ridge 168, examples
of which are shown in FIGS. 6 and 8. Lobes 162 are adjacently
arranged to provide troughs 172, inner channels 174, inner chutes
176, outer channels 184, and outer chutes 186 that turn about axis
F in a manner analogous to mixer 50. Furthermore, mixer 150
utilizes a mixing technique analogous to mixer 50. The shading dots
in FIG. 6 schematically represent receding regions corresponding to
troughs 172.
[0051] Each lobe 162 includes a wall portion 194 extending from a
first one of its corresponding pair of walls 164 farther downstream
along axis F than a second one of its corresponding pair of walls
164 at outlet 158. Only a few of wall portions 194 are specifically
designated to preserve clarity. It should be understood that outer
surface portion 196 of each wall portion 194 follows the twisting
path about axis F to cover a corresponding inner chute 176 relative
to a view plane downstream of outlet 158, such as the view plane of
FIG. 7. Because inner chute surface 177 of each inner chute 176 is
directly exposed to hot exhaust gas as it flows through passage 154
from inlet 156 to outlet 158, surface 177 typically presents a more
intense thermal signature than outer surface portion 196 of each
wall portion 194 relative to this downstream view plane.
Correspondingly, for each pair of lobe walls 164, wall portion 194
extending from one of lobe walls 164 blocks the opposite lobe wall
164 from a view along a line of sight parallel to axis F from a
position downstream of outlet 158.
[0052] In some arrangements, wall portions 194 may provide
additional blockage of hot parts, such as turbine blades 35 and
centerbody 39 for the same degree of twist relative to mixer 50.
Furthermore, mixer 150 with wall portions 194 may be employed in
situations where less twist is desired with comparable or greater
thermal signature reduction. Referring back to FIG. 3, one
alternative embodiment of mixer 150 may be provided through
modification of mixer 50. For this adaptation, an outlet region 98
of lobes 62 that has a hot inner surface visible through outlet 158
is removed (only a few regions 98 are illustrated to preserve
clarity). Referring again to FIGS. 6-8, the effect of this
adaptation is to form a side wall slot 198 in each lobe, leaving
wall portion 194 opposite the side wall slot 198.
[0053] Mixer 250 of another embodiment of the present invention is
illustrated in the side, elevational view of FIG. 9; the end,
elevational view of FIG. 10; and the top left, isometric view of
FIG. 11. Mixer 250 includes duct 252 with passage 254 extending
from inlet 256 to outlet 258 in a manner analogous to mixer 150.
Furthermore, mixer 250 can be interchanged with mixer 50, 150 in
mixing system 40 of aircraft 20 as described in connection with
FIGS. 1-8. Mixer 250 includes lobes 262 each defined by a
corresponding pair of side walls 264 radially extending from axis F
and coupled together by a corresponding dome 266 to form a
corresponding ridge 268, an example of which is specifically
designated by reference numerals in FIG. 9. Lobes 262 are
adjacently arranged to provide troughs 272, inner channels 274,
inner chutes 276, outer channels 284, and outer chutes 286 that
turn about axis F in a manner analogous to mixer 50, 150 (only a
few of which are designated to preserve clarity). The shading dots
in FIG. 9 schematically represent receding regions corresponding to
troughs 272.
[0054] Each lobe 262 includes a wall portion 294 extending a first
one of its corresponding pair of walls 264 farther downstream along
axis F than a second one of its corresponding pair of walls at
outlet 258. Only a few of wall portions 294 are specifically
designated to preserve clarity. It should be understood that outer
surface portion 296 of each wall portion 294 follows the twisting
path about axis F to cover or hide a corresponding inner chute 276
relative to a view plane downstream of outlet 258, such as the view
plane of FIG. 10 to reduce thermal signature as described in
connection with mixer 150.
[0055] As in the case of wall portions 194 of mixer 150, wall
portions 294 of mixer 240 provide additional blockage of hot parts
for the same degree of twist relative to mixer 50. Furthermore,
mixer 250 with wall portions 294 may be employed in situations
where more blockage is desired with less twist relative to mixer
50. Moreover, wall portions 294 terminate in a curved end portion
295 configured to turn working fluid as it exits outlet 258. Only a
few of portions 295 are specifically designated to preserve
clarity. The curvature of portions 295 is preferably configured to
turn at least a portion of the working fluid back towards axis F,
providing for the recovery of at least some of the loss that might
arise due to swirl caused by the mixing action. Correspondingly,
wall portions 294 each provide a region 297 that curves in a
direction opposite the direction of the twist about axis F to
provide a coanda surface 298.
[0056] Mixer 350 of another embodiment of the present invention is
illustrated in the end, elevational view of FIG. 12; the schematic
partial sectional, end view of FIG. 13 with centerbody 39; and the
top left, isometric view of FIG. 14 with centerbody 39. Mixer 350
includes duct 352 with passage 354 extending from inlet 356 to
outlet 358 in a manner analogous to mixers 50, 150, 250.
Furthermore, mixer 350 can be interchanged with mixer 50, 150, 250
in mixing system 40 of aircraft 20 as described in connection with
FIGS. 1-11. Mixer 350 includes the twisted lobe/trough structure of
mixer 50 with like reference numerals representing like features.
Specifically, mixer 350 includes lobes 62 each defined by a
corresponding pair of walls 64 radially extending from axis F and
coupled together by a corresponding dome 66 to form a ridge 68, an
example of which is specifically designated by reference numerals
in FIG. 12. Lobes 62 are adjacently arranged to provide troughs 72,
inner channels 74, inner chutes 76, outer channels 84, and outer
chutes 86 that turn about axis F in a manner analogous to mixer 50
(only a few of which are shown to preserve clarity).
[0057] Mixer 350 includes a number of blocking fins 392 that each
extend into passage 354 along toward axis F along a different
radius. Only a few of fins 392 may be specifically designated to
preserve clarity. From the view plane of FIG. 12, fins 392 form a
spiral pattern about axis F (represented by cross hairs). Fins 392
each emanate from an inner surface 394 of conduit 352 at a minimum
radius point bounding outlet 358, an example of which is designated
as point MRP in the sectional view of FIG. 13. The schematic
sectional view of FIG. 13 presents a sectional contour of mixer 350
along a plane perpendicular to and intersecting axis F between
inlet 356 and outlet 358 of mixer 350. Axis F is perpendicular to
the view plane of FIG. 13 and is represented by cross hairs.
[0058] The minimum radius point MRP generally coincides with the
location where two adjacent lobes 62 meet at the bottom of a trough
72. Accordingly, fins 392 each follow a spiral path of a different
trough 72, and each correspond to one of lobes 62, inner channels
74, inner chutes 76, outer channels 84 and outer chutes 86. From
the view plane of FIG. 12, the twisted path followed by each fin
392 provides further blockage of hot parts in addition to the
obstruction caused by twisting inner channels 74 and corresponding
inner chutes 76. It should be understood that in other embodiments,
more or fewer fins 392 may be utilized for the same number of lobes
62 and/or troughs 72, or may be absent altogether.
[0059] Mixer 450 of another embodiment of the present invention is
illustrated in the end, elevational view of FIG. 15; the schematic
partial sectional, end view of FIG. 16 with centerbody 39; and the
top left, isometric view of FIG. 17 with centerbody 39. Mixer 450
includes duct 452 with passage 454 extending from inlet 456 to
outlet 458 in a manner analogous to mixers 50, 150, 250, 350.
Furthermore, mixer 450 can be interchanged with mixer 50, 150, 250,
350 in mixing system 40 of aircraft 20 as described in connection
with FIGS. 1-14. Mixer 450 includes the twisted lobe/trough
structure of mixer 50 with like reference numerals representing
like features. Specifically, mixer 450 includes lobes 62 each
defined by a corresponding pair of walls 64 radially extending from
axis F and coupled together by a corresponding dome 66 to form a
ridge 68, an example of which is specifically designated by
reference numerals in FIG. 15. Lobes 62 are adjacently arranged to
provide troughs 72, inner channels 74, inner chutes 76, outer
channels 84, and outer chutes 86 that turn about axis F in a manner
analogous to mixer 50 (only a few of which are designated to
preserve clarity).
[0060] As in the case of mixer 350, mixer 450 includes a number of
blocking fins 492 that each extend into passage 454 toward axis F.
Only a few of fins 492 may be specifically designated to preserve
clarity. From the view plane of FIG. 15, fins 492 form a spiral
pattern about axis F (represented by cross hairs). Fins 492 each
emanate from an inner surface 494 of conduit 452, and generally
extending one of each pair of walls 64 comprising a lobe 62.
Collectively, the wall 64 and the extending fin 492 are designated
extended wall portion 464 as depicted in FIG. 16. It should be
understood that the extension of each fin 492 into passage 454 is
offset from the minimum radius point from which fins 392 emanate.
This offset is best seen by comparing the sectional view of FIG. 13
for mixer 350 to the schematic sectional view of FIG. 16 for mixer
450, where the cross section of FIG. 16 corresponds to a sectional
contour of mixer 450 along a plane perpendicular to and
intersecting axis F at a position between inlet 456 and outlet 458.
Fins 492 provide additional blockage of hot parts relative to mixer
350 and follow a twisting path corresponding to the twist of lobes
62, troughs 72, inner channels 74, inner chutes 76, outer channels
84, and outer chutes 86. In alternative embodiments, the position
of fins 492 relative to each other and corresponding lobes 62
and/or troughs 72 may be varied, may be intermixed with fins 392,
may vary in number relative to the number of lobes 62 and/or
troughs 72, or may be absent.
[0061] Mixer 550 of another embodiment of the present invention is
illustrated in the end, elevational view of FIG. 18; the schematic
partial sectional, end view of FIG. 19 with centerbody 39; and the
top left, isometric view of FIG. 20 with centerbody 39. Mixer 550
includes duct 552 with passage 554 extending from inlet 556 to
outlet 558 in a manner analogous to mixer 50, 150, 250, 350, 450.
Furthermore, mixer 550 can be interchanged with mixer 50, 150, 250,
350, 450 in mixing system 40 of aircraft 20 described in connection
with FIGS. 1-17. Mixer 550 includes lobes 562 each defined by a
corresponding pair of side walls 564 radially extending from axis F
and coupled together by a corresponding dome 566 to form a ridge
568, an example of which is specifically designated by reference
numerals in FIG. 18. Lobes 562 are adjacently arranged to provide
troughs 572, inner channels 574, inner chutes 576, outer channels
584, and outer chutes 586 that turn about axis F in a manner
analogous to mixer 50, 150, 250, 350, 450.
[0062] Mixer 550 includes a number of hollow cooling fins in the
form of vanes 592 that each extend into passage 554 toward axis F
along a different radius. Only a few of vanes 592 may be
specifically designated to preserve clarity. From the view plane of
FIG. 18, vanes 592 form a spiral pattern about axis F (represented
by cross hairs). Vanes 592 each emanate from an inner surface 594
of conduit 552 at a minimum radius point bounding outlet 558, an
example of which is designated as point MRP in the schematic
sectional contour of mixer 550 shown in FIG. 19. The schematic
sectional contour of FIG. 19 is taken along a plane perpendicular
to and intersecting axis F between inlet 556 and outlet 558 of
mixer 550. Axis F is perpendicular to the view plane of FIG. 19 and
is represented by cross hairs.
[0063] The minimum radius point MRP generally coincides with the
location where two adjacent lobes 562 meet at the bottom of a
trough 572. Accordingly, vanes 592 each follow a spiral path of a
different trough 572, and each correspond to one of lobes 562,
inner channels 574, inner chutes 576, outer channels 584 and outer
chutes 586. From the view plane of FIG. 18, the twisted path
followed by each vane 392 provides further blockage of hot parts in
addition to the obstruction caused by twisting inner channels 574
and corresponding inner chutes 576.
[0064] Each one of vanes 592 defines a passageway 593 therethrough.
Each passageway 593 has an opening 595 intersecting a corresponding
outer channel 584 and an opening 597 intersecting plenum 539 within
centerbody 39 via plenum opening 599 as best illustrated in FIG.
19. Accordingly, passageways 593 provide fluid communication
between each corresponding outer channel 584 and plenum 539. Vanes
592 and corresponding passageways 593 are preferably configured to
supply cooling fluid, such as air from outer channels 584 to cool
centerbody 39 of engine 32 to suppress its thermal signature. In
one embodiment, opening 595 of each passageway 593 is configured to
capture the total (stagnation) pressure of the outer cooling fluid
flowing though the outer channel 584 it intersects. Typically this
arrangement creates a cooling air driving potential for air
originating from each outer channel 584 to pass into a respective
one of passageways 593 through its opening 595, and enter plenum
539 through corresponding openings 597 and 599. Centerbody 39 may
also include one or more slits, slots, or other openings to vent
cooling fluid from plenum 539 as appropriate (not shown). Notably
in another embodiment, fewer than all of vanes 592 include
passageway 593. In still other embodiments, vanes 592 may be
variously positioned relative to each other and lobes 562 analogous
to fins 392, 492, or may be absent altogether. In still other
embodiments centerbody 39 may lack a plenum 539 and/or openings 599
or may be absent.
[0065] The components of aircraft 20, mixing system 40 and mixers
50, 150, 250, 350, 450, 550 are preferably made from standard
materials selected to perform as intended in the environment
expected. For example, mixers 50, 150, 250, 350, 450, 550 may be
made of a metallic material, a ceramic material, a composite
material, or a combination of these selected to withstand expected
exhaust temperatures. Furthermore, coatings may be applied to
mixing system components according to the present invention to
further suppress thermal signal and/or reduce radar cross
section.
[0066] Many further embodiments of the present invention are
envisioned. For instance, in other embodiments, the features of any
of mixers 50, 150, 250, 350, 450, or 550 may be combined, deleted,
altered, duplicated or otherwise rearranged as would occur to those
skilled in the art without departing from the spirit of the present
invention. In other examples, the curved or twisting pattern in one
or more of mixers 50, 150, 250, 350, 450, 550, may have a different
shape, such as a counter-twist, to offset any losses that might
occur for a particular configuration. In still other embodiments,
the twisted or curved lobes and/or troughs are absent, instead
following a generally straight path with respect to axis F.
Moreover, the size and shape of lobes, troughs, channels, chutes,
wall portions, and fins may vary, may be nonuniformly distributed
about axis F, and/or may not follow a uniform pattern of curvature
or twist with respect to a reference axis. For example, only a
portion of such features may be curved, two or more degrees of
curvature or twist may be employed, different features may have
different degrees of twist or curvature, and/or one or more of
these features may be S-shaped. In another example, lobes of the
present invention may not have a rounded, curvilinear shape, but
rather have an angular or rectilinear shape. Further, a mixer
according to the present invention may utilize lobes or troughs
that twist or curve relative to a reference axis other than the
centerline axis of the mixer. In other embodiments, fins and/or
vanes may or may not be twisted or may follow a different twist or
curvature pattern than lobes or troughs. In yet other embodiments,
one or more other structures like fins 343, 443 and/or vanes 543
may be utilized to the exclusion of twisted lobes and/or troughs to
provide the requisite blockage. Also, wall portions, blocking fins
and vanes of mixers 150, 250, 350, 450, 550 may be intermixed
and/or positions of the structures varied with respect to the
lobe/trough structure in a given mixer application. For instance,
fins of both the side wall extending type and those emanating
between side walls from a minimum radius point or otherwise can be
utilized in the same mixer. In yet other embodiments of the present
invention, variations and modifications as would otherwise occur to
one skilled in the art are envisioned.
[0067] In a further embodiment of the present invention, an exhaust
mixer includes a passage extending from an inlet to an outlet to
convey an exhaust flow therethrough. Several lobes are also
included that are circumferentially disposed about the axis and
that each define a corresponding one of several inner channels.
These inner channels intersect one another between the inlet and
the outlet. The lobes are each shaped to turn the inner channels
about the axis to block viewing of the inlet through the lobes from
a view plane perpendicular to the axis and downstream of the
outlet.
[0068] Still another embodiment includes a gas turbine engine and
an exhaust mixer coupled to the engine along an outlet. This mixer
includes several outward ridges radially projecting away from the
axis that each define one of a number of inner channels
intersecting at least one other of the inner channels within the
mixer. These ridges are each shaped to turn the channels about the
axis.
[0069] In yet another embodiment, a gas turbine engine is included
that is operable to produce an exhaust flow. Also included is a
conduit coupled to the engine along an axis to mix the exhaust flow
with cooling air. This conduit includes a number of lobes each
defining a corresponding one of several inner channels
circumferentially disposed about the passage. These lobes are each
shaped to turn a corresponding one of the channels about the axis
as they advance therealong. Also, a number of fins are included
that each extend into the passage along the conduit and each
converge with one or more other of the fins as the axis is
approached.
[0070] In a further alternative, an apparatus includes a gas
turbine engine operable to produce an exhaust flow and a mixer
coupled to the engine along an axis to mix the exhaust flow with
cooling air. This mixer includes a passage positioned along the
axis to convey the exhaust flow therethrough, several inner chutes
circumferentially disposed about the passage, several outer chutes
circumferentially disposed about the passage, and a number of vanes
extending into the passage. The outer chutes are each positioned
between a respective pair of inner chutes and the vanes each
include a passageway in fluid communication with the corresponding
one of the outer chutes.
[0071] In a further alternative embodiment, an apparatus includes a
gas turbine engine and a mixer coupled to the engine along an axis
to mix cooling air with an exhaust flow produced during engine
operation. This mixer includes an inlet and an outlet opposite the
inlet along the axis and a number of lobes radially disposed about
the axis. These lobes each turn about the axis between the inlet
and outlet. The lobes include a number of wall portions at the
outlet that each extend a first side of a respective one of the
lobes past a second side of a respective one of the lobes along the
axis to reduce thermal signature of the apparatus.
[0072] In yet a further embodiment, a mixer is coupled to a gas
turbine engine along an axis to mix cooling air with an exhaust
flow produced during engine operation. This mixer includes an inlet
and an outlet opposite the inlet along the axis, a number of inner
chutes, and a number of wall portions at the outlet. The inner
chutes are radially disposed about the axis and each turn about the
axis as the inner chutes each extend therealong. The wall portions
each extend from a corresponding one of the inner chutes to block
the view of the corresponding one of the inner chutes from
downstream of the outlet along a line of site parallel to the
axis.
[0073] In a still further embodiment, an apparatus includes a gas
turbine engine and a mixer coupled to the engine along an axis to
mix cooling air with an exhaust flow produced during engine
operation. This mixer includes an inlet and an outlet opposite the
inlet along the axis and a number of lobes radially disposed about
the axis. The lobes each turn about the axis between the inlet and
the outlet as the lobes each extend along this axis. The lobes each
include a respective one of a number of first walls opposite a
respective one of a number of second walls. The respective one of
the first walls hides the respective one of the second walls from
view along a line of site parallel to the axis that originates
downstream of the outlet.
[0074] All publications, patents, and patent applications cited
herein are hereby incorporated by reference as if each individual
publication, patent or patent application were specifically and
individually indicated to be incorporated by reference and set
forth in its entirety herein including, but not limited to U.S.
Pat. No. 4,576,002 to Mavrocostas; U.S. Pat. No. 4,566,270 to
Ballard et al.; U.S. Pat. No. 4,548,034 to Maguire; U.S. Pat. No.
4,543,784 to Kirker; and 4,487,017 to Rodgers and U.S. Provisional
Application No. 60/114,623 filed Jan. 4, 1999. While the invention
has been illustrated and described in detail in the drawings and
foregoing description, the same is to be considered as illustrative
and not restrictive in character, it being understood that only the
preferred embodiment has been shown and described and that all
changes, modifications, and equivalents that come within the spirit
of the invention as defined by the following claims are desired to
be protected.
* * * * *