U.S. patent application number 10/865025 was filed with the patent office on 2005-12-15 for gas turbine engine inlet with noise reduction features.
This patent application is currently assigned to United Technologies Corporation. Invention is credited to Feng, Jinzhang, Prasad, Dilip, Sabnis, Jayant S..
Application Number | 20050274103 10/865025 |
Document ID | / |
Family ID | 34941646 |
Filed Date | 2005-12-15 |
United States Patent
Application |
20050274103 |
Kind Code |
A1 |
Prasad, Dilip ; et
al. |
December 15, 2005 |
Gas turbine engine inlet with noise reduction features
Abstract
A gas turbine engine comprising a fan section, a compressor, a
combustor and a turbine, includes a nacelle having an inner nacelle
surface defining an inlet duct designed to reduce an inlet duct
area of the inlet duct to increase acoustic attenuation. The gas
turbine engine also includes a spinner, disposed forward of the fan
section, that includes features to increase acoustic attenuation.
In one embodiment of the present invention, the nacelle includes a
nacelle contoured surface protruding radially inward from the inner
nacelle surface to reduce the inlet duct area. In a further
embodiment of the present invention, the spinner includes a spinner
contoured surface for reducing the inlet duct area. In other
embodiments, the nacelle and/or the spinner include an inflatable
bladder, a SMA actuator, a fluidic actuator, or a combination
thereof, selectively activated to increase acoustic attenuation
during certain conditions of an aircraft.
Inventors: |
Prasad, Dilip; (Vernon,
CT) ; Feng, Jinzhang; (Avon, CT) ; Sabnis,
Jayant S.; (Glastonbury, CT) |
Correspondence
Address: |
MCCORMICK, PAULDING & HUBER LLP
CITY PLACE II
185 ASYLUM STREET
HARTFORD
CT
06103
US
|
Assignee: |
United Technologies
Corporation
Hartford
CT
|
Family ID: |
34941646 |
Appl. No.: |
10/865025 |
Filed: |
June 10, 2004 |
Current U.S.
Class: |
60/226.1 ;
137/15.1 |
Current CPC
Class: |
B64D 2033/0286 20130101;
B64D 33/02 20130101; Y10T 137/0536 20150401; F02C 7/042 20130101;
F02C 7/045 20130101; B64D 2033/0206 20130101 |
Class at
Publication: |
060/226.1 ;
137/015.1 |
International
Class: |
F02K 003/04 |
Claims
What is claimed is:
1. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; and
means for reducing an inlet duct area of the inlet duct to increase
acoustic attenuation.
2. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area is disposed forward of the fan
section.
3. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area is disposed on the inner nacelle
surface.
4. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area includes a nacelle contoured surface
protruding radially inward from the inner nacelle surface to reduce
the inlet duct area.
5. The gas turbine engine according to claim 4 wherein the nacelle
contoured surface defines a throat.
6. The gas turbine engine according to claim 4 wherein the nacelle
contoured surface reduces the inlet duct area to increase Mach
number of incoming air.
7. The gas turbine engine according to claim 4 further comprising
means for selectively reducing the inlet area disposed on the
nacelle contoured surface.
8. The gas turbine engine according to claim 7 wherein the means
for selectively reducing the inlet area comprises an inflatable
bladder.
9. The gas turbine engine according to claim 7 wherein the means
for selectively reducing the inlet area comprises an SMA
actuator.
10. The gas turbine engine according to claim 7 wherein the means
for selectively reducing the inlet area comprises a fluidic
actuator.
11. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area includes a spinner contoured surface
formed on a spinner disposed forward of the fan section.
12. The gas turbine engine according to claim 11 wherein the
spinner contoured surface is a substantially blunt surface
protruding forward farther than a conventional spinner surface.
13. The gas turbine engine according to claim 11 wherein the
spinner contoured surface extends into a hub of a fan disposed
within the fan section of the engine.
14. The gas turbine engine according to claim 11 further comprising
means for selectively reducing the inlet area disposed on the
spinner contoured surface.
15. The gas turbine engine according to claim 14 wherein the means
for selectively reducing the inlet area comprises an inflatable
bladder.
16. The gas turbine engine according to claim 14 wherein the means
for selectively reducing the inlet area comprises an SMA
actuator.
17. The gas turbine engine according to claim 14 wherein the means
for selectively reducing the inlet area comprises a fluidic
actuator.
18. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area includes a nacelle contoured surface
formed on the inner nacelle surface and a spinner contoured surface
formed on a spinner disposed forward of the fan section.
19. The gas turbine engine according to claim 18 wherein the
nacelle contoured surface and the spinner contoured surface reduce
the inlet area to increase Mach number of incoming air.
20. The gas turbine engine according to claim 18 further comprising
means for selectively reducing the inlet area disposed on the
nacelle contoured surface and on the spinner contoured surface.
21. The gas turbine engine according to claim 20 wherein the means
for selectively reducing the inlet area comprises an inflatable
bladder.
22. The gas turbine engine according to claim 20 wherein the means
for selectively reducing the inlet area comprises an SMA
actuator.
23. The gas turbine engine according to claim 20 wherein the means
for selectively reducing the inlet area comprises a fluidic
actuator.
24. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area is asymmetrical.
25. The gas turbine engine according to claim 24 wherein the means
for reducing the inlet area is asymmetrical such that a lower
portion of the nacelle includes a contour that protrudes a greater
amount than the contour at an upper portion of the nacelle.
26. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area includes means for selectively reducing
the inlet area.
27. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area has a distended position
and a retracted position.
28. The gas turbine engine according to claim 27 wherein the means
for selectively reducing the inlet area in the distended position
protrudes radially inward into the inlet duct area to reduce the
inlet duct area thereby increasing Mach number of air incoming into
the gas turbine engine.
29. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is selectively
activated.
30. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is activated during a
takeoff condition.
31. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is activated during a
flyover condition.
32. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is activated during takeoff
and flyover conditions.
33. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is asymmetrical.
34. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is asymmetrical such that a
lower portion of the nacelle includes a contour that protrudes a
greater amount than the contour at an upper portion of the
nacelle.
35. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is disposed on an inner
nacelle surface of the nacelle.
36. The gas turbine engine according to claim 35 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface.
37. The gas turbine engine according to claim 36 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area and the means for
selectively reducing the inlet area protrudes further inward to
further reduce the inlet duct area during activated condition.
38. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is disposed on a spinner
surface of a spinner wherein the spinner is disposed forward of the
fan section.
39. The gas turbine engine according to claim 38 wherein the
spinner surface includes a spinner contoured surface.
40. The gas turbine engine according to claim 39 wherein the
spinner contoured surface protrudes from the spinner surface to
reduce the inlet duct area and the means for selectively reducing
the inlet area protrudes further to further reduce the inlet duct
area during activated condition.
41. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area is disposed on an inner
nacelle surface of the nacelle and on a spinner surface of a
spinner wherein the spinner is disposed forward of the fan
section.
42. The gas turbine engine according to claim 41 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface and wherein the spinner surface includes a
spinner contoured surface.
43. The gas turbine engine according to claim 42 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area; wherein the spinner
contoured surface protrudes from the spinner surface to reduce the
inlet duct area; and wherein the means for selectively reducing the
inlet area protrudes further to further reduce the inlet duct area
during activated condition.
44. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area comprises an inflatable
bladder.
45. The gas turbine engine according to claim 44 wherein the
inflatable bladder is disposed on an inner nacelle surface of the
nacelle.
46. The gas turbine engine according to claim 45 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface.
47. The gas turbine engine according to claim 46 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area and the inflatable
bladder protrudes further inward to further reduce the inlet duct
area during deployed condition.
48. The gas turbine engine according to claim 44 wherein the
inflatable bladder is disposed on a spinner surface of a spinner
wherein the spinner is disposed forward of the fan section.
49. The gas turbine engine according to claim 48 wherein the
spinner surface includes a spinner contoured surface.
50. The gas turbine engine according to claim 49 wherein the
spinner contoured surface protrudes from the spinner surface to
reduce the inlet duct area and the inflatable bladder protrudes
further to further reduce the inlet duct area during activated
condition.
51. The gas turbine engine according to claim 44 wherein the
inflatable bladder is disposed on an inner nacelle surface of the
nacelle and on a spinner surface of a spinner wherein the spinner
is disposed forward of the fan section.
52. The gas turbine engine according to claim 51 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface and wherein the spinner surface includes a
spinner contoured surface.
53. The gas turbine engine according to claim 52 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area; wherein the spinner
contoured surface protrudes from the spinner surface to reduce the
inlet duct area; and wherein the inflatable bladder protrudes
further to further reduce the inlet duct area during deployed
condition.
54. The gas turbine engine according to claim 44 wherein the
inflatable bladder comprises: a bladder; a plenum; and means to
inflate the plenum.
55. The gas turbine engine according to claim 54 wherein the means
to inflate the plenum includes an inlet for allowing pressurized
air to enter the plenum.
56. The gas turbine engine according to claim 54 further
comprising: means to deflate the plenum.
57. The gas turbine engine according to claim 44 wherein the
inflatable bladder is asymmetrical with respect to circumference of
the nacelle.
58. The gas turbine engine according to claim 57 wherein the
inflatable bladder is asymmetrical such that the inflatable bladder
disposed in a lower portion of the nacelle protrudes a greater
amount than the inflatable bladder disposed at an upper portion of
the nacelle when the inflatable bladder is in deployed
position.
59. The gas turbine engine according to claim 44 wherein the
inflatable bladder is segmented around the circumference of the
nacelle to allow asymmetrical deployment thereof.
60. The gas turbine engine according to claim 44 wherein the
inflatable bladder has a distended position and a retracted
position.
61. The gas turbine engine according to claim 60 wherein the
inflatable bladder in the distended position protrudes radially
inward into the inlet duct area to reduce the inlet duct area
thereby increasing Mach number of air incoming into the gas turbine
engine.
62. The gas turbine engine according to claim 26 wherein the means
for selectively reducing the inlet area comprises an SMA
actuator.
63. The gas turbine engine according to claim 62 wherein the SMA
actuator is asymmetrical with respect to circumference of the
nacelle.
64. The gas turbine engine according to claim 63 wherein the SMA
actuator is asymmetrical such that the SMA actuator disposed in a
lower portion of the nacelle protrudes a greater amount than the
SMA actuator disposed at an upper portion of the nacelle when the
SMA actuator is in deployed position.
65. The gas turbine engine according to claim 62 wherein the SMA
actuator is segmented around the circumference of the nacelle to
allow asymmetrical deployment thereof.
66. The gas turbine engine according to claim 62 wherein the SMA
actuator has a distended position and a retracted position.
67. The gas turbine engine according to claim 66 wherein the SMA
actuator in the distended position protrudes radially inward into
the inlet duct area to reduce the inlet duct area thereby
increasing Mach number of air incoming into the gas turbine
engine.
68. The gas turbine engine according to claim 62 wherein the SMA
actuator is disposed on an inner nacelle surface of the
nacelle.
69. The gas turbine engine according to claim 68 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface.
70. The gas turbine engine according to claim 69 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area and the SMA actuator
protrudes further inward to further reduce the inlet duct area
during deployed condition.
71. The gas turbine engine according to claim 62 wherein the SMA
actuator is disposed on a spinner surface of a spinner wherein the
spinner is disposed forward of the fan section.
72. The gas turbine engine according to claim 71 wherein the
spinner surface includes a spinner contoured surface.
73. The gas turbine engine according to claim 72 wherein the
spinner contoured surface protrudes from the spinner surface to
reduce the inlet duct area and the SMA actuator protrudes further
to further reduce the inlet duct area during activated
condition.
74. The gas turbine engine according to claim 62 wherein the SMA
actuator is disposed on an inner nacelle surface of the nacelle and
on a spinner surface of a spinner wherein the spinner is disposed
forward of the fan section.
75. The gas turbine engine according to claim 74 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface and wherein the spinner surface includes a
spinner contoured surface.
76. The gas turbine engine according to claim 75 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area; wherein the spinner
contoured surface protrudes from the spinner surface to reduce the
inlet duct area; and wherein the SMA actuator protrudes further to
further reduce the inlet duct area during deployed condition.
77. The gas turbine engine according to claim 62 wherein the SMA
actuator comprises: at least one SMA member having a distended
position and a retracted position such that in the distended
position the at least one SMA member protrudes radially inward into
the inlet area to reduce the inlet area thereby increasing Mach
number of air incoming into the gas turbine engine.
78. The gas turbine engine according to claim 77 further
comprising: means to deactivate the SMA actuator.
79. The gas turbine engine according to claim 1 wherein the means
for reducing the inlet area is a fluidic actuator.
80. The gas turbine engine according to claim 79 wherein the
fluidic actuator is asymmetrical with respect to circumference of
the nacelle.
81. The gas turbine engine according to claim 80 wherein the
fluidic actuator is asymmetrical such that the fluidic actuator
disposed in a lower portion of the nacelle interferes with the
incoming flow a greater amount than the fluidic actuator disposed
at an upper portion of the nacelle when the fluidic actuator is
activated.
82. The gas turbine engine according to claim 79 wherein the
fluidic actuator is segmented around the circumference of the
nacelle to allow asymmetrical deployment thereof.
83. The gas turbine engine according to claim 79 wherein the
fluidic actuator has an activated position and a deactivated
position.
84. The gas turbine engine according to claim 83 wherein the
fluidic actuator in the activated position generates an inward flow
of air into the inlet duct area to effectively reduce the inlet
duct area thereby increasing Mach number of air incoming into the
gas turbine engine.
85. The gas turbine engine according to claim 79 wherein the
fluidic actuator is disposed on an inner nacelle surface of the
nacelle.
86. The gas turbine engine according to claim 85 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface.
87. The gas turbine engine according to claim 86 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area and the fluidic
actuator generates air inward into the inlet duct to effectively
further reduce the inlet duct area during activated condition of
the fluidic actuator.
88. The gas turbine engine according to claim 79 wherein the
fluidic actuator is disposed on a spinner surface of a spinner
wherein the spinner is disposed forward of the fan section.
89. The gas turbine engine according to claim 88 wherein the
spinner surface includes a spinner contoured surface.
90. The gas turbine engine according to claim 89 wherein the
spinner contoured surface protrudes from the spinner surface to
reduce the inlet duct area and the fluidic actuator generates air
into the inlet duct to effectively further reduce the inlet duct
area during activated condition of the fluidic actuator.
91. The gas turbine engine according to claim 79 wherein the
fluidic actuator is disposed on an inner nacelle surface of the
nacelle and on a spinner surface of a spinner wherein the spinner
is disposed forward of the fan section.
92. The gas turbine engine according to claim 91 wherein the inner
nacelle surface of the nacelle is contoured to form a nacelle
contoured surface and wherein the spinner surface includes a
spinner contoured surface.
93. The gas turbine engine according to claim 92 wherein the
nacelle contoured surface protrudes radially inward from the inner
nacelle surface to reduce the inlet duct area; wherein the spinner
contoured surface protrudes from the spinner surface to reduce the
inlet duct area; and wherein the fluidic actuator generates air
into the inlet duct to effectively further reduce the inlet duct
area during activated condition of the fluidic actuator.
94. The gas turbine engine according to claim 79 wherein the
fluidic actuator includes means for selectively blowing air into
the inlet duct to effectively reduce the inlet duct area of the
nacelle.
95. The gas turbine engine according to claim 79 wherein the
fluidic actuator is selectively activated to effectively reduce the
inlet duct area of the nacelle.
96. The gas turbine engine according to claim 95 wherein the
fluidic actuator comprises: an air injector for injecting air into
flow path of air incoming into the gas turbine engine.
97. The gas turbine engine according to claim 95 wherein the air
injector includes an opening formed within the inner nacelle
surface.
98. The gas turbine engine according to claim 95 wherein the air
injector is being fed pressurized air channeled from another
portion of the engine.
99. A gas turbine engine comprising: a fan section; and a nacelle
enclosing the gas turbine engine and forming an inlet duct forward
of the fan section; and wherein the nacelle is designed to
introduce local increases in the Mach number of air-incoming into
the gas turbine engine to enhance shock wave dissipation.
100. A gas turbine engine comprising: a fan section; a nacelle
enclosing the gas turbine engine and forming an inlet duct forward
of the fan section; and a spinner disposed forward of the fan
section and disposed substantially centrally with respect to the
nacelle; wherein the nacelle and the spinner are designed to
introduce local increases in the Mach number of air incoming into
the gas turbine engine to enhance shock wave dissipation.
101. A gas turbine engine comprising: a fan section; a nacelle
enclosing the gas turbine engine and forming an inlet duct forward
of the fan section; and a spinner disposed forward of the fan
section and disposed substantially centrally with respect to the
nacelle; wherein the spinner is designed to introduce local
increases in the Mach number of air incoming into the gas turbine
engine to enhance shock wave dissipation.
102. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct, wherein
the inner nacelle surface is contoured to increase acoustic
attenuation.
103. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; a
spinner disposed forward of the fan section and disposed
substantially centrally with respect to the nacelle, the spinner
having a spinner surface; wherein the spinner surface is contoured
to increase acoustic attenuation.
104. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; a
spinner disposed forward of the fan section and disposed
substantially centrally with respect to the nacelle, the spinner
having a spinner surface; wherein the inner nacelle surface and the
spinner surface are contoured to increase acoustic attenuation.
105. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; and
means for selectively reducing the inlet area disposed on the inner
nacelle surface to increase acoustic attenuation during certain
conditions of an aircraft.
106. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; a
spinner disposed forward of the fan section and disposed
substantially centrally with respect to the nacelle, the spinner
having a spinner surface; and means for selectively reducing the
inlet area disposed on the spinner surface to increase acoustic
attenuation during certain conditions of an aircraft.
107. A gas turbine engine comprising: a nacelle enclosing a fan
section, a compressor, a combustor and a turbine, the nacelle
including an inner nacelle surface defining an inlet duct; a
spinner disposed forward of the fan section and disposed
substantially centrally with respect to the nacelle, the spinner
having a spinner surface; and means for selectively reducing the
inlet area disposed on the inner nacelle surface and on the spinner
surface to increase acoustic attenuation during certain conditions
of an aircraft.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to gas turbine engines and,
more particularly, to reduction of noise emanating therefrom.
[0003] 2. Background Art
[0004] In recent years, noise generated by flying aircraft has
attracted attention and is now subject of various governmental
regulations. Efforts need to be made to minimize annoyance to
neighborhoods located in the path of departing and landing
aircraft. The noise is especially disturbing during certain flight
conditions such as takeoffs and landings of the aircraft.
[0005] The aircraft noise is primarily generated by gas turbine
engines propelling the aircraft. One major source of the noise
generated by the gas turbine engine is the fan section. The fan
generates tonal and broadband acoustic energy propagating outward
of the engine through an inlet and through a bypass nozzle.
[0006] Various considerations dictate design of the gas turbine
engine that propels an aircraft. For example, several critical
concerns are thrust of the engine, fuel efficiency, cooling, and
the overall weight. Frequently, optimization of one factor results
in undesirable consequences for another. Therefore, design of an
engine includes multiple trade-offs to obtain an optimal engine.
Although noise generated by the gas turbine engine is now subject
to fairly stringent governmental regulations, to date, the noise
considerations were not part of the design optimization for
conventional engines.
SUMMARY OF THE INVENTION
[0007] According to the present invention, a gas turbine engine
comprises a nacelle enclosing a fan section, a compressor, a
combustor and a turbine, with the nacelle including an inner
nacelle surface defining an inlet duct and means for reducing an
inlet duct area of the inlet duct to increase acoustic attenuation
during certain conditions of an aircraft. The means for reducing
the inlet area is disposed on an inner nacelle surface or on a
spinner, disposed forward of the fan section, or on both, the inner
nacelle surface and the spinner surface.
[0008] In one embodiment of the present invention, the means for
reducing the inlet area includes a nacelle contoured surface
protruding radially inward from the inner nacelle surface to reduce
the inlet duct area. In another embodiment of the present
invention, the means for reducing the inlet area includes a spinner
contoured surface protruding into the inlet duct to reduce the
inlet duct area. In yet another embodiment, the means for reducing
the inlet area comprises means for selectively reducing the inlet
area. In a further embodiments, the means for selectively reducing
the inlet area comprises an inflatable bladder, a SMA actuator, a
fluidic actuator, or a combination thereof. The inflatable bladder,
the SMA actuator, and the fluidic actuator are disposed on an inner
nacelle surface or on a spinner, or on both, the inner nacelle
surface and the spinner surface. The means for selectively reducing
the inlet area may be also used in combination with the nacelle
and/or spinner contoured surfaces.
[0009] The foregoing and other advantages of the present invention
become more apparent in light of the following detailed description
of the exemplary embodiments thereof, as illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic representation of a gas turbine
engine;
[0011] FIG. 2 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to one embodiment of the present invention;
[0012] FIG. 3. is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0013] FIG. 4 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0014] FIG. 5 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0015] FIG. 6 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0016] FIG. 6A is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0017] FIG. 7 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0018] FIG. 8 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0019] FIG. 9 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0020] FIG. 10 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0021] FIG. 10A is a schematic, partially broken-away
representation of a portion of a nacelle and fan section including
means for reducing inlet area of the gas turbine engine of FIG. 1
according to a further embodiment of the present invention;
[0022] FIG. 11 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0023] FIG. 12 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to a further embodiment of the present invention;
[0024] FIG. 13 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0025] FIG. 14 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0026] FIG. 15 is a schematic, partially broken-away representation
of a portion of a nacelle and fan section including means for
reducing inlet area of the gas turbine engine of FIG. 1 according
to another embodiment of the present invention;
[0027] FIG. 16 is a schematic representation of a forward portion
of a nacelle of the gas turbine engine of FIG. 1 and a
corresponding graph of isentropic Mach number corresponding to the
internal portion of the nacelle.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0028] Referring to FIG. 1, a gas turbine engine 10 includes a fan
section 12, a compressor 14, a combustor 16, and a turbine 18
centered around a central axis 20 and enclosed in a nacelle 22. Air
24 flows axially through the sections 12-18 of the engine 10
forming streamlines 25, as seen in FIG. 2. The fan section 12
includes a fan 26 which accelerates the air 24 to contribute to the
overall thrust generated by the engine. As is well known in the
art, the air 24, compressed in the compressor 14, is mixed with
fuel and burnt in the combustor 16. Subsequently, the hot gases
expand in the turbine 18 generating thrust to propel the engine 10
and to drive the turbine 18, which in turn drives the fan 26 and
the compressor 14.
[0029] Referring to FIG. 2, the nacelle 22 includes an outer
nacelle surface 30 and an inner nacelle surface 32 joined at a
nacelle leading edge 34. The nacelle also includes a lower portion
38 and an upper portion 40. The inner nacelle surface 32 defines an
inlet duct 42 having an inlet duct area.
[0030] The fan 26 of the engine 10 includes a plurality of fan
blades 46 and a spinner 48 disposed forward of the fan 26. Each fan
blade 46 comprises an airfoil-shaped portion 50 that spans radially
from a root 52 to a tip 54 and extends from a leading edge 58 to a
trailing edge 60. The root of each fan blade is inserted into a hub
62. The engine 10 of FIG. 2 further includes means for reducing the
inlet area 64. In several embodiments of the present invention, the
means for reducing the inlet area includes means for selectively
reducing the inlet area 66 of the nacelle. One such embodiment,
shown in FIG. 2, includes an inflatable bladder 70 disposed on the
inner nacelle surface 32. The bladder 70 comprises a bladder
surface 72 and a plenum 74 disposed radially outward of the bladder
surface 72. The plenum is fed pressurized fluid via a pressure feed
76. The pressurized fluid can be channeled from various other
portions of the engine, such as, for example, the compressor. The
bladder 70 has a distended position and a retracted position. In
the distended position, shown in FIG. 2, the bladder reduces the
inlet duct area of the nacelle, forming a throat 82. In the
retracted position, the bladder surface 72 is substantially flush
with the inner nacelle surface 32. The plenum 74 can be either
actively depressurized or allowed to deflate gradually from the
distended position into the retracted position.
[0031] Referring to FIG. 3, in another embodiment of the present
invention, the means for selectively reducing the inlet area 66
includes an SMA actuator 84 comprising a plurality of SMA (shape
memory alloy) members 86 disposed radially outward of a compliant
surface 88. As is well known in the art, the SMA material changes
shape when it is heated and resumes its original shape once the
heating is seized, or vice versa. Thus, the means for selectively
reducing the inlet area 66 has two positions, a distended position
and a retracted position. In the distended position, the SMA
members are heated and force the compliant surface 88 to extend
into the inlet duct area, thereby reducing the diameter of the
inlet duct 42 and defining the throat 82 of the inlet duct. The SMA
members are either actively cooled or allowed to cool to resume its
initial position. In the initial position, the SMA members retract
and allow the compliant surface to be substantially flush with the
inner nacelle surface 32. The SMA members 86 can have various
configurations. For example, the SMA members can be in the form of
either rings, ropes or other shapes.
[0032] Referring to FIG. 4, the means for selectively reducing the
inlet area 66 of the nacelle in this embodiment is a fluidic
actuator 90. The fluidic actuator is disposed within the nacelle 22
and includes an air injector 92 having an opening 94 formed within
the inner nacelle surface 32 and being fed pressurized air
channeled from another portion of the engine 10. The fluidic
actuators 90 further include switching means 96 for switching
between activated and deactivated condition. In the activated
condition, the pressurized air is blown through the opening 94 of
the air injector 92 radially inward of the inner nacelle surface 32
into the inlet duct 42. In the deactivated condition, the
pressurized air is turned off and no air comes through the air
injector.
[0033] Referring to FIG. 5, in a further embodiment of the present
invention, the means for reducing the inlet area 64 includes a
nacelle contoured surface 100 formed on the inner nacelle surface
32 that reduces the inlet duct area 42 to define the throat 82
therebetween. The nacelle contoured surface 100 is formed at the
forward portion of the nacelle toward the nacelle leading edge 34
and defines a relatively steep and localized contour.
[0034] Referring to FIG. 6, in a further embodiment of the present
invention, the means for reducing the inlet area 64 includes a
nacelle contoured surface 102 formed on the inner nacelle surface
that reduces the inlet duct area to define the throat 82
therebetween. The nacelle contoured surface 102 extends from the
nacelle leading edge 34 axially downstream toward the fan 26. The
nacelle contoured surface 102 is formed on the inner nacelle
surface 32 and is less steep than the nacelle contoured surface 100
shown in FIG. 5.
[0035] Referring to FIG. 6A, the means for reducing the inlet area
64 includes a contoured surface 103 and means for selectively
reducing the inlet area 66. Although FIG. 6A shows the means for
selectively reducing the inlet area as the inflatable bladder, the
means for reducing the inlet area 66 can be either the SMA or
fluidic actuator, or others. Thus, the contoured surface 103
reduces the inlet duct area defining the throat 82 and the means
for reducing the inlet area 66 further reduces the inlet duct area
when in deployed or activated condition.
[0036] Referring to FIG. 7, the means for reducing the inlet area
64 may comprise or include a spinner contoured surface 104 formed
on the spinner 48, disposed forward of the fan section. The spinner
contoured surface 104 extends further forward of the conventional
spinner surface and provides a more blunt spinner shape. Either
alone or in combination with a contoured nacelle surfaces 100, 102,
the spinner contoured surface 104 reduces the inlet duct area.
[0037] Referring to FIGS. 8-10, in these embodiments of the present
invention, the means for selectively reducing the inlet area 66 of
the nacelle includes the means for selectively varying spinner
contour 108. Thus, as shown in FIG. 8, the spinner 48 includes an
inflatable bladder 170 to selectively decrease the inlet duct area.
As shown in FIG. 9, the spinner 48 includes an SMA actuator 184
having a flexible surface 188 with an SMA member 186 to selectively
activate the SMA material. As shown in FIG. 10, the spinner 48
includes a fluidic actuator 190 to output pressurized air into the
flow path of air 24. The inflatable bladder 170, the SMA actuator
184 and the fluidic actuator 190, disposed within the spinner, are
substantially analogous to those described above and shown in FIGS.
2-4. The bladder 170, the SMA actuator 184 and the fluidic actuator
190 disposed on the spinner can be either used in conjunction with
those disposed in the nacelle or alone. Additionally, the bladder
170, the SMA actuator 184 and the fluidic actuator 190 can be
disposed in a conventional spinner, as shown in FIGS. 8-10, or be
used in conjunction with a blunt spinner as shown in FIG.1OA.
[0038] Referring to FIGS. 11-15, in further embodiments of the
present invention, the means for reducing the inlet area 64 is
asymmetrical with respect to the nacelle with the upper portion 40
of the nacelle 22 having smaller protrusion relative to the lower
portion 38 of the nacelle. As shown in FIG. 11, an inflatable
bladder 270 is segmented around the circumference of the nacelle
with the bladder in the lower portions 38 of the nacelle either
having a greater amount of air pressure supplied or having a larger
bladder. With respect to FIG. 12, an SMA actuator 284 either has a
greater degree of actuation in the lower portion 38 of the nacelle
22 or is a segmented SMA actuator. With respect to FIG. 13, the
lower portion 38 of the nacelle 22 includes either greater amount
of air or air at higher pressure channeled than the upper portion
40 of the nacelle. With respect to FIGS. 14 and 15, the contoured
surfaces 300, 302 protrude more radially inward in the lower
portion 38 of the nacelle 22.
[0039] In operation, for embodiments described above and shown in
FIGS. 2-3, 8-13, the means for selectively reducing the inlet area
66 is activated during the acoustic sideline (takeoff) and/or
flyover (cutback) conditions of the engine. Thus, as the means for
selectively reducing the inlet area 66 are activated during takeoff
and cutback conditions, the bladder 70, 170, 270 and the SMA
actuator 84, 184, 284, shown in FIGS. 2 and 3, respectively, are
activated into distended position to reduce the inlet duct area,
thereby forming the throat 82. The throat, with significantly
reduced inlet duct area, increases shock decay. Contraction of the
flow path of air 24 increases curvature of the streamlines 25 and
results in acceleration of the mean flow 24, thereby increasing the
Mach number of the incoming airflow 24, as shown in FIG. 16. The
elevated Mach number of the incoming air 24 during the takeoff and
cutback conditions counteracts the acoustic power radiating from
the inlet, thereby enhancing noise attenuation. The noise generated
by the fan 26 is most significant at the takeoff and cutback
conditions as the rotor speed at the tip 54 of the fan blades 50 is
supersonic, thereby generating a shock wave field at the leading
edge 58 of each blade toward the tip 54 of the blade. The shock
waves suffer a natural decay process as they propagate upstream of
the fan, and the resulting unsteady pressure emerging from the
inlet propagates outside of the engine as tone noise. The rate of
decay of the shock pattern through the inlet duct depends on the
Mach number of the flow approaching the rotor. The greater the Mach
number of the incoming flow 24, the greater is the rate of
attenuation of the noise generated by the fan section 12. The
introduction of local increases in the Mach number enhances shock
wave dissipation during the most critical conditions, such as
takeoff and cutback. However, during other conditions, for example,
such a cruise, it may be undesirable to have reduction in the
intake duct area. Therefore, for other conditions, such as a cruise
condition, the bladder, SMA actuator and fluid actuator are
deactivated and the nacelle inlet area is restored to its original
size.
[0040] Referring to FIG. 4, the fluidic actuator 90 is activated
during certain engine conditions to generate flow of air to
interfere with incoming air 24. Such interference causes effective
reduction of inlet duct area for incoming flow and effectively
forms throat 82.
[0041] Referring to FIG. 5, the nacelle contoured surface 100
provides for rapid acceleration and increase in Mach number of the
incoming flow 24 to reduce the emanating noise. However, other
engine design considerations may make rapid acceleration and
increase in Mach number undesirable. For example, the elevated Mach
number renders the inlet susceptible to separation when crosswind
is present. Therefore, depending on a particular engine and
specific other considerations, it may be desirable to either have
rapid acceleration as shown in FIG. 5 or have a more moderately
high Mach number value held over a greater portion of the duct
length shown in FIG. 6 and illustrated in FIG. 16.
[0042] Referring to FIG. 6A, the contoured surface 103 formed on
the inner nacelle surface 32 reduces the inlet duct area during all
operating conditions of the engine. The means for reducing the
inlet area 66 further reduces the inlet duct area when the means
for reducing the inlet area 66 is in the deployed or activated
condition. This configuration is beneficial since the contoured
surface 103 may have a slight contour to slightly increase Mach
number of incoming air 24. The means for selectively reducing the
inlet area 66 would enhance noise attenuation during critical
conditions of engine operation, such as takeoff and fly over.
[0043] Referring to FIG. 7, the spinner contoured surface 104
enhances effectiveness of dissipation of shock waves. The spinner
48 having more blunt shape and extending forward of a conventional
spinner has the effect of squeezing the streamlines 25 between the
spinner 48 and nacelle throat 82 resulting in increased Mach number
of the incoming airflow 24. Additionally, the fan blade hub 62 may
also need to be changed to further increase effectiveness of the
present invention. As shown in FIGS. 8-10, the means for
selectively varying spinner contour 108 are also activated during
the takeoff and cutback conditions and deactivated during other
conditions, such as cruise. The means for selectively varying
spinner contour 108 may be used alone or in as part of the means
for reducing the inlet area 64. Additionally, the means for
selectively varying spinner contour 108 can be used alone, as shown
in FIGS. 5, 8 and 9, or in combination with spinner contoured
surface 104, as shown in FIG. 10.
[0044] Referring to FIGS. 11-15, the means for reducing the inlet
area 64 as described above, may not be symmetrically. As is known
in the art, it is desirable to minimize the acoustic power radiated
downward from the aircraft. Therefore, the Mach number of the
incoming flow of air 24 is increased to the greater extent at the
lower portion 38 of the nacelle 22 to achieve greater attenuation
at the lower portion 38 of the nacelle relative to the upper
portion 40 of the nacelle. Thus, the means for reducing the inlet
area 64 extend radially inward and interfere with the incoming air
24 to a greater extent at the lower portion 38 of the nacelle than
the upper portion 40 thereof. This design allows attenuation of
noise in the area that presents greater problem while minimizing
interference with incoming airflow 24 at locations that present
lesser problem.
[0045] One major advantage of the present invention is that it
addresses reduction of noise emanating from a gas turbine engine.
Thus, either permanent or selective reduction of noise in a gas
turbine engine renders the engine in compliance with new and more
stringent regulations promulgated by various authorities. Although
embodiments showing permanent changes to the contour of the inner
nacelle surface and/or the spinner, such as shown in FIGS. 5-7 and
14-15 are useful in certain engine applications, the embodiment
with selective variation of the inner nacelle surface contour are
more widely applicable and can be used on a wider variety of
engines. The means for selectively reducing inlet area 66 allows
maximization of noise reduction during critical conditions, such as
takeoff and cutback, without interfering with operating conditions
of the engine during other conditions, such as cruise.
[0046] While the present invention has been illustrated and
described with respect to a particular embodiment thereof, it
should be appreciated by those of ordinary skill in the art that
various modifications to this invention may be made without
departing from the spirit and scope of the present invention. For
example, any combination of means for reducing the inlet area 64
can be used. More specifically, the means for selectively reducing
the inlet area 66 such as the inflatable bladder, the SMA actuator
and the fluidic actuator, can be used either alone on the inner
nacelle surface and/or on the spinner surface, or in combination
with either or both, the nacelle contoured surface and/or the
spinner contoured surface.
* * * * *