CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No. 611580,675,
filed December 28,2011, which is incorporated by reference.
BACKGROUND
The subject matter disclosed herein relates generally to muffling systems, and, more
specifically, to muffling devices capable of inducing high pressure drops and desirable flow
properties.
In a gas turbine engine, air is pressurized in a compression module during
operation. The air channeled through the compression module is mixed with fuel in a
combustor and ignited, generating hot combustion gases which flow through turbine stages
that extract energy therefrom for powering the fan and compressor rotors and generate engine
thrust to propel an aircraft in flight or to power a load, such as an electrical generator.
In some gas turbine engines, a portion of the high-pressure air, such as, for example,
bleed air from a compressor, may be extracted or bled from the compressor for various needs.
These needs include, for example, compressor flow bleeding which may be used in order to
improve operability as well as to provide turbine cooling, pressurize bearing sumps, purge air
or provide aircraft environment control. The air may be bled off from the compressor using
bleed slots located over specific portions or stages of the compressor.
The problem: In least some gas turbine engines, during engine operation occurring
in some operating conditions, the compressor may pump more air than is required for needs
including the combustion process. In order to manage operability of the engine and
combustion performance, a portion of the excess bleed air from the compressor may be
routed through bleed conduits and exhausted into the by-pass flow stream, engine exhaust, or
to ambient. The pressure and temperature of the air stream bled from the compressor may be
very high. For example, bleed air pressure may be greater than about 1375 kPa and the bleed
air temperature may be greater than about 538 degrees C. A transient bleed valve system
(TBV) system is sometimes used for bleeding and exhausting the air removed from the
compressor. Certain conventional designs for bleed exhaust systems use large and/or heavy
muffling devices to reduce the generated noise. For example, the exhaust area of some
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conventional bleed systems may be set to lower the flow velocity at the exhaust location to a
level below that required to meet the acoustic limits for the application. The exhaust area, as
well as the relatively gently expansions between the source pressure and exhaust, may
contribute to the relatively large size and/or weight of these systems. In some applications
(e.g., aircraft), it may be undesirable to use large and/or heavy components.
In addition, some conventional exhaust designs on aircraft may require extensive
thermal shielding on other components near the exhaust location, once the exhaust velocities
that meet the acoustic limits are achieved. Due to the nature of the high temperature air, once
it is over-expanded to achieve lower velocities, the air it mixes with may overwhelm the
bleed air, causing it to "lay down" on the surrounding structure around the engine. In some
aircraft the surrounding structure may be made of lightweight composite material, or of other
metallic material with lesser temperature capability.
BRIEF DESCRIPTION OF THE INVENTION
The solution for the above-mentioned problem is provided by the present disclosure
to include example embodiments, provided for illustrative teaching and not meant to be
limiting.
An example muffling device according to at least some aspects of the present
disclosure may include an inner flow conditioner comprising an inlet, the inlet being
configured to convey a pressurized fluid flow into an inner flow conditioner interior, the
inner flow conditioner comprising a plurality of inner flow conditioner holes; and an exhaust
can disposed substantially around the inner flow conditioner and arranged to receive the
pressurized fluid flow via the inner flow conditioner holes into an exhaust can interior, the
exhaust can comprising an exhaust screen comprising a plurality of exhaust screen holes
arranged to discharge the pressurized fluid flow from the exhaust can interior. The exhaust
can interior may be substantially devoid of flow obstructions between the plurality of inner
flow conditioner holes and the exhaust screen holes. A ratio of an effective flow area of the
inner flow conditioner holes to an effective flow area of the inlet may be about 0.7 to about
1.75. A ratio of an effective flow area of the exhaust screen holes to the effective flow area
ofthe inlet may be about 0.9 to about 2.8.
An example muffling device according to at least some aspects of the present
disclosure may include an inner flow conditioner comprising an inlet, the inlet being
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configured to convey a pressurized fluid flow into an inner flow conditioner interior, the
inner flow conditioner comprising a plurality of inner flow conditioner holes; and an exhaust
can disposed substantially around the inner flow conditioner and arranged to receive the
pressurized fluid flow via the inner flow conditioner holes into an exhaust can interior, the
exhaust can comprising an exhaust screen comprising a plurality of exhaust screen holes
arranged to discharge the pressurized fluid flow from the exhaust can interior. The exhaust
can interior may be substantially devoid of flow obstructions between the plurality of inner
flow conditioner holes and the exhaust screen holes. A ratio of a volume of the inner flow
conditioner interior to a volume of the exhaust can interior may be about 0.06 to about 0.40.
An example muffling device according to at least some aspects of the present
disclosure may include an inner flow conditioner shaped as a generally conical frustum
comprising an upstream base and a downstream base, a diameter of the upstream base being
larger than a diameter ofthe downstream base. The inner flow conditioner may include an
inlet approximate the upstream base, a generally circular inner flow conditioner downstream
end wall, the inner flow conditioner downstream end wall being generally orthogonal to a
longitudinal axis of the conical frustum and comprising a plurality of generally longitudinally
oriented inner flow conditioner downstream end wall holes, and an inner flow conditioner
sidewall shaped generally as a truncated cone, the inner flow conditioner sidewall tapering
inwardly from approximate the upstream base to approximate the inner flow conditioner
downstream wall, the inner flow conditioner sidewall comprising a plurality of generally
laterally oriented inner flow conditioner sidewall holes. The example muffling device may
include an exhaust can disposed substantially around the inner flow conditioner and shaped
as a generally circular cylinder. The exhaust can my include a generally annular upstream
end wall disposed approximate the upstream base ofthe inner flow conditioner and
substantially circumscribing the upstream base of the inner flow conditioner, a generally
circular exhaust screen comprising a plurality of exhaust screen holes, and a generally
circular exhaust can sidewall extending from approximate the upstream end wall to
approximate the exhaust screen. The inner flow conditioner and the exhaust can may be
configured to conduct a fluid inward through the inlet into the inner flow conditioner,
through the inner flow conditioner downstream end wall discharge openings and the inner
flow conditioner sidewall discharge openings into the exhaust can, and outward through the
exhaust screen discharge openings.
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BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter for which patent claim coverage is sought is particularly pointed
out and claimed herein. The subject matter and embodiments thereof, however, may be best
understood by reference to the following description taken in conjunction with the
accompanying drawing figures in which:
FIG. I is a schematic cross-sectional view of an example gas turbine engine
assembly including an example bleed system including an example muffling device;
FIG. 2 is a perspective view of an example bleed system including an example
muffling device;
FIG. 3 is a cross-sectional view of an example muffling device;
FIG. 4 is a partial-cutaway, perspective view of an example muffling device;
FIG. 5 is a cross-sectional view of an alternative example muffling device; and
FIG. 6 is a cross-sectional view of an alternative example muffling device; all
in accordance with at least some aspects ofthe present disclosure.
DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying
drawings, which form a part hereof. In the drawings, similar symbols typically identify
simila.r components, unless context dictates otherwise. The illustrative embodiments
described in the detailed description, drawings, and claims are not meant to be limiting.
Other embodiments may be utilized, and other changes may be made, without departing from
the spirit or scope of the subject matter presented here. It will be readily understood that the
aspects of the present disclosure, as generally described herein, and illustrated in the figures,
can be arranged, substituted, combined, and designed in a wide variety of different
configurations, all of which are explicitly contemplated and make part ofthis disclosure.
The present disclosure includes, inter alia, muffling systems, and more specifically
muffling devices capable of inducing high pressure drops and desirable flow properties.
The present disclosure contemplates that modem, highly efficient turbofan engines
may use high-pressure/high-temperature bleed from the aft compressor stages to improve
operability and performance. This bleed air may be directed into the fan duct or other
locations, which may generate additional noise during some phases of engine operation.
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Some example embodiments according to the present disclosure provide a compact,
lightweight transient/operability bleed exhaust muffling device (which may be referred to
generally as a "pepperpot") that has minimal acoustic impact. Acoustic benefit for the high
pressure/temperature compressor discharge bleed may be achieved at a high exhaust velocity
into the fan duct and, in some example embodiments, may use only a single flow
conditioning element (which may be referred to as an "inner flow conditioner") within the
pepperpot body (which may be referred to as an "exhaust can"). Some such embodiments
may be referred to as "single stage" muffling devices. The present disclosure contemplates
that some other acoustic pepperpots may utilize multiple (e.g., three to five or more) inner
flow conditioning elements, which may add weight to the engine.
In addition, the present disclosure contemplates that some other acoustically
friendly pepperpots may necessitate extensive shielding on the thrust reverser structure to
address thermal concerns. Some example embodiments according to the present disclosure
may reduce or eliminate the need for such shielding by directing at least a substantial portion
ofthe high-temperature bleed air generally to the middle of the cool fan duct flow, which
may allow the hot plume to exit the fan duct without substantially impinging on thrust
reverser or other aircraft surfaces.
FIG. 1 is a schematic cross-sectional view of an example gas turbine engine
assembly 10 including an example bleed system 40 including an example muffling device 50,
according to at least some aspects of the present disclosure. FIG. 2 is a perspective view of
bleed system 40 including muffling device 50, according to at least some aspects of the
present disclosure. The gas turbine engine assembly 10 includes a core gas turbine engine 12
that includes a high-pressure compressor 14, a combustor 16, and a high-pressure turbine 18.
In the example embodiment shown in FIG.!, the gas turbine engine assembly 10 also
includes a low-pressure turbine 20 coupled axially downstream from core gas turbine engine
12 and a fan assembly 22 coupled axially upstream from core gas turbine engine 12. Fan
assembly 22 includes an array of fan blades 24 that extend radially outward from a rotor disk.
In the exemplary embodiment shown in FIG.!, gas turbine engine assembly 10 has an intake
side 28 and an exhaust side 29. Core gas turbine engine 12, fan assembly 22, and lowpressure
turbine 20 are coupled together by a first rotor shaft 31, and high-pressure
compressor 14 and high-pressure turbine 18 are coupled together by a second rotor shaft 32.
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In operation, air flows through fan blades 24 and is supplied to high-pressure
compressor 14. The air discharged from fan assembly 22 is channeled to high-pressure
compressor 14 where the airflow is further compressed and channeled to combustor 16.
Products of combustion from combustor 16 are utilized to drive high-pressure turbine 18 and
low-pressure turbine 20, and turbine 20 drives fan assembly 22 via shaft 31.
In an example gas turbine engine assembly 10, at certain operating conditions, a
portion of the compressed air may be routed through the bleed system 40, thereby becoming
bleed air 2. Bleed air 2 from high-pressure compressor 14 may enter a bleed flow conduit 44.
Bleed air 2 may pass through the bleed flow conduit 44 and enter muffling device 50 that
directs bleed air 2 into a flow path, such as the by-pass flow path 4 and mixes that air with
another flow, such as a fan flow stream 1. Flow through bleed flow conduit 44 may be
controlled by a bleed air valve 45. Bleed flow conduit 44 may be made from a variety of
materials, such as a metal, which may be selected to be capable of withstanding a bleed air 2
flow that is relatively hot and at high pressure.
Muffling device 50, described in more detail herein below, may be in flow
communication with bleed flow conduit 44 such that the bleed air 2 is discharged as exit flow
stream 5 into by-pass flow path 4, facilitating a reduction of the noise generated by the
mixing of the exit flow stream 5 and fan flow stream 1.
As shown in FIG. 2, bleed flow conduit 44 may have a length 47 between bleed air
valve 45 and muffling device 50. Muffling device 50 may have a length 49 between bleed
flow conduit 44 and by-pass flow path 4, such as the length of exhaust can 102 (FIG. 3). In
some example embodiments according to at least some aspects of the present disclosure,
length 49 of muffiing device 50 may be less than about half of the sum of length 49 of
muffling device and length 47 of bleed flow conduit 44. In some example embodiments
according to at least some aspects of the present disclosure, length 49 of muffling device 50
may be less than about one third of the sum oflength 49 ofmuffiing device and length 47 of
bleed flow conduit 44. In some example embodiments according to at least some aspects of
the present disclosure, length 49 of muffiing device 50 may be less than about one quarter of
the sum oflength 49 ofmuffiing device and length 47 of bleed flow conduit 44. In some
example embodiments according to at least some aspects of the present disclosure, some or
all ofthe acoustic improvements provided by this device occur within the exhaust can (e.g.,
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within length 49), which may allow the use of relatively small diameter and lightweight
ducting to direct the flow to a location very close to the exhaust can.
FIG. 3 is a cross-sectional view of an example muffling device 50, according to at
least some aspects of the present disclosure. FIG. 4 is a partial-cutaway, perspective view of
an example muffling device 50, according to at least some aspects of the present disclosure.
Muffling device 50 may comprise an exhaust can 102, which may include an exhaust screen
104 (which may be generally circular), an upstream end wall 126 (which may be generally
annular), and a sidewall 128 (which may be generally circular). Exhaust can 102 may be
generally in the form of a hollow circular cylinder arranged about a central axis 124 with a
diameter 130. Exhaust screen 104 may include a plurality of holes 106 through which air
may be discharged from an interior 108 of exhaust can 102. In some example embodiments,
exhaust screen 104 may be outwardly curved.
In some example embodiments according to at least some aspects of the present
disclosure, an inner flow conditioner 110 may be disposed within exhaust can 102. Inner
flow conditioner 110 may be generally in the form of a hollow, conical frustum arranged
coaxially with exhaust can 102 about central axis 124. Inner flow conditioner 110 may
include an inwardly tapering sidewall 112 and a downstream end wall 114, which may be
generally circular. Sidewall 112 may be shaped generally as a truncated cone. Downstream
end wall 114 may be generally orthogonal to central axis 124. Inner flow conditioner 110
may taper inwardly from an upstream base 136 (which may be substantially circumscribed by
upstream end wall 126) to a downstream base 138 (which may be proximate downstream end
wall 114). Sidewall 112 and downstream end wall 114 may at least partially define an
interior 116 of inner flow conditioner 110. Sidewall 112 may include a plurality of generally
laterally oriented holes 120 and/or downstream end wall 114 may include a plurality of
generally axially oriented holes 122 through which pressurized air may be discharged into
interior 108 of exhaust can 102. Inner flow conditioner 110 may be arranged to receive
pressurized air from bleed flow conduit 44 through an inlet 118 (which may be proximate
upstream base 136). Inner flow conditioner 110 may have an upstream base diameter 132
proximate inlet 118 and/or downstream base diameter 134 proximate downstream end wall
114. Upstream base diameter 132 may be larger than downstream base diameter 134. Inner
flow conditioner 110 may be attached inside exhaust can 102 such that inlet 118 is disposed
within upstream end wall 126 of exhaust can 102.
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In operation, inner flow conditioner 110 and exhaust screen 102 may be configured
to conduct pressurized air inward through inlet 118 into interior 116 of inner flow conditioner
110, through holes 120 and/or holes 122 of inner flow conditioner 110 into interior 108 of
exhaust can 102, and outward through holes 106 of exhaust screen 104. In some example
embodiments interior 108 of exhaust can 102 may be substantially devoid of flow
obstructions between holes 120 and holes 122 of inner flow conditioner and holes 106 of
exhaust screen 104.
FIG. 5 is a cross-sectional view of an alternative example muffling device 200,
according to at least some aspects ofthe present disclosure. Muffling device 200 may
comprise an exhaust screen 204 (which may be generally in the form of a hollow cylinder),
an upstream end wall 226 (which may be generally annular), a sidewall 228, that combine to
form an assembly exhaust can 202. Exhaust screen 204 may include a plurality of holes 206
through which air may be discharged from an interior 208 of exhaust can 202. An inner flow
conditioner 210 may be disposed within interior 208 of exhaust can 202. Inner flow
conditioner 210 may be generally in the form of a hollow, conical frustum including an
inwardly tapering sidewall 212 and a downstream end wall 214. Inner flow conditioner 210
may taper inwardly from an upstream base 236 to a downstream base 238 (which may be
proximate downstream end wall 214). Inner flow conditioner 210 may be arranged generally
coaxially with exhaust can 202. Sidewall 212 and downstream end wall 214 may at least
partially define an interior 216 of inner flow conditioner 210. Sidewall 212 may include a
plurality of holes 220 and/or downstream end wall 214 may include a plurality of holes 222
through which air may be discharged into interior 208 of exhaust can 202. Inner flow
conditioner 210 may be arranged to receive air from bleed flow conduit 44 through an inlet
218 (which may be proximate upstream base 236).
Muffling device 200 (FIG. 5) may be generally similar to muffling device 50 (FIGS.
3 and 4), described above. Muffling device 200 may differ from muffling device 50 in that it
may include, for example, an inner flow conditioner 210 that may differ in shape and/or size
from inner flow conditioner 110. For example, inner flow conditioner 110 of muffling device
50 may extend approximately halfway from upstream end wall 126 to exhaust screen 104 of
exhaust can 102, while inner flow conditioner 210 may extend substantially more than half
way from upstream end wall 226 to exhaust screen 204 of exhaust can 202 of muffling device
200. Example embodiments according to the present disclosure may include inner flow
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conditioners having various shapes and sizes. For example, some embodiments according to
the present disclosure may include inner flow conditioners having shapes other than truncated
cones.
FIG. 6 is a cross-sectional view of an alternative example muffling device 300,
according to at least some aspects of the present disclosure. Muffling device 300 may
comprise an exhaust can 302 (which may be generally in the form of a hollow cylinder) and
which may include an upstream end wall 326 (which may be generally annular), a sidewall
328, and/or an exhaust screen 304. Exhaust screen 304 may include a plurality of holes 306
through which air may be discharged from an interior 308 of exhaust can 302. Exhaust
screen 304 may be substantially flat and/ or curved. An inner flow conditioner 310 may be
disposed within interior 308 of exhaust can 302. Inner flow conditioner 310 may be
generally in the form ofa hollow, cylinder including a sidewall 312 and a downstream end
wall 314. Downstream end wall 314 may be substantially flat. Inner flow conditioner 310
may be arranged generally coaxially with exhaust can 302. Sidewall 312 and downstream
end wall 314 may at least partially define an interior 316 of inner flow conditioner 310.
Sidewall 312 may include a plurality of holes 320 (which may be in the form of slots) and/or
downstream end wall 314 may include a plurality ofholes 322 through which air may be
discharged into interior 308 of exhaust can 302. Inner flow conditioner 310 may be arranged
to receive air from bleed flow conduit 44 through an inlet 318. In some example
embodiments, holes 320 through sidewall 312 of inner flow conditioner 310 may be
substantially larger than holes 322 through downstream end wall 314. In some example
embodiments, inner flow conditioner 310 may effectively comprise a flat plate forming
downstream end wall 314 supported over inlet 318 and/or sidewall 312 of inner flow
conditioner 310 may not substantially affect fluid flowing around downstream end wall 314.
Example muffling devices 50, 200, 300 may include holes 106, 120, 122,206,220,
222, 306, 320 322 having individual hole sizes (e.g., diameters and/or slot length/width) and
areas. An individual hole may have an effective area for fluid flow that differs from its
measurable physical area. A hole's effective area for fluid flow may be determined by
known methods, and may depend on the size and shape of the hole. A plurality of holes, e.g.,
holes 106 of exhaust screen 104, may have an effective area for fluid flow that may be
calculated using known methods.
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In some example embodiments according to at least some aspects of the present
disclosure, a ratio of an effective flow area ofthe holes (e.g., holes 120 and holes 122) of an
inner flow conditioner (e.g., inner flow conditioner 110) to an effective flow area of an inlet
(e.g., inlet 118) may be about 0.7 to about 1.75. In some example embodiments according to
at least some aspects of the present disclosure, a ratio of an effective flow area of the holes of
the inner flow conditioner to an effective flow area of the inlet may be about 0.75 to about
0.86.
In some example embodiments according to at least some aspects of the present
disclosure, a ratio of an effective flow area of holes (e.g., holes 106 of an exhaust screen
(e.g., exhaust screen 104) to an effective flow area of an inlet (e.g., inlet 118) may be about
0.9 to about 2.8. In some example embodiments according to at least some aspects of the
present disclosure, a ratio of an effective flow area of the holes of the exhaust screen to an
effective flow area of the inlet may be about 1.0 to about 1.9. In some example embodiments
according to at least some aspects ofthe present disclosure, a ratio of an effective flow area
of the holes of the exhaust screen to an effective flow area of the inlet may be about 2.6 to
about 2.7.
Some example embodiments according to at least some aspects of the present
disclosure may be configured such that the volumes of some elements are related. For
example, an interior (e.g., interior 116) of an inner flow conditioner (e.g., inner flow
conditioner 110) may have a volume. For example, the volume of inner flow conditioner 110
may be defined by sidewall 112, downstream end wall 114, and/or inlet 118. Similarly, an
interior (e.g., interior 108) of an exhaust can (e.g., exhaust can 102) may have a volume. For
example, the volume of exhaust can 102 may be defined by sidewall 128, exhaust screen 104,
upstream end wall 126, sidewall 112 (of inner flow conditioner 110), and/or downstream end
wall 114 (of inner flow conditioner 110). As used herein, the volume ofthe exhaust can may
not include the volume ofthe inner flow conditioner, despite the inner flow conditioner being
disposed within the exhaust can in some example embodiments.
In some example embodiments according to at least some aspects of the present
disclosure, a ratio of a volume of an inner flow conditioner to a volume of an exhaust can
may be about 0.06 to about 0.40. In some example embodiments according to at least some
aspects of the present disclosure, the ratio of the volume ofthe inner flow conditioner to a
volume of the exhaust can may be about 0.10 to about 0.22. In some example embodiments
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according to at least some aspects ofthe present disclosure, the ratio of a volume of the inner
flow conditioner to a volume of the exhaust can may be about 0.125 to about 0.195. In some
example embodiments according to at least some aspects ofth~ present disclosure, these
example volume ratios may provide a beneficial interaction due to cavity impedance
differences, based on test and analysis.
Some example embodiments according to the present disclosure may be configured
such that the velocity of an exit flow stream (e.g., exit flow stream 5 of FIGS. I and 2) is
generally constant across the holes of the exhaust screen (e.g., holes 106 of exhaust screen
104 of exhaust can 102) at some flow conditions. For example, some embodiments may be
configured such that the average ideal (e.g., isentropic) Mach number of the flow through
holes 106 is greater than about 0.8 and the maximum ideal Mach number of the flow through
holes 106 is less than about 1.2. More specifically, some embodiments may be configured
such that the average ideal Mach number of the flow through holes 106 is greater than about
0.85 and the maximum ideal Mach number of the flow through holes 106 is less than about
1.15. Even more specifically, some embodiments may be configured such that the average
ideal Mach number of the flow through holes 106 is about 0.95 and the maximum ideal Mach
number of the flow velocity through holes 106 is about 1.1. The present disclosure
contemplates that limiting the variation in the flow velocity through holes 106 across exhaust
screen 104 may provide acoustic benefits by reducing mixing and/or reducing shear noise
within the exhaust plume. The present disclosure contemplates that limiting the variation in
the flow through holes 106 across downstream end wall 104 may produce a tight exhaust
plume in by-pass flow path 4, which may reduce the risk ofthermally damaging surfaces of
adjacent aircraft structure (like the thrust reverser) that may be less capable of the
temperature or thermal environment.
Some example embodiments may be configured to produce back pressure at bleed
air valve 45 sufficient to reduce the shock intensity across bleed air valve 45, thus lessening
the acoustic impact. Some example embodiments may be configured to hide upstream
noise-generating elements, such as the high-pressure compressor 14, bleed air valve 45, and
flow turning, by changing the frequency of upstream noise to a lower energy acoustic
excitation. Some example embodiments may be configured to break up expansion waves as
the flow transitions from the relatively small bleed flow conduit 44 to the relatively larger
exhaust can 202, such that the expansion waves do not substantially propagate through holes
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6106 of exhaust screen 104 and into by-pass flow path 4 (or other discharge location). Some
example embodiments may be configured to provide a beneficial acoustic interaction
between a generally conical inner flow conditioner 110 and holes 106 of exhaust screen 104
of exhaust can 102.
Some example embodiments may be configured such that, at some flow conditions,
the ideal Mach number at bleed air valve 45 is about 1.5 to about 1.95. Some example
embodiments may be configured such that, at some flow conditions, the ideal Mach number
at bleed air valve 45 is about 1.6 to about 1.8.
Some example embodiments may be configured such that, at some flow conditions,
the average ideal Mach number at the inner flow conditioner is about 0.9 to about 1.8. Some
example embodiments may be configured such that, at some flow conditions, the average
Mach number at the inner flow conditioner is about 0.95 to about 1.75.
Some example embodiments may be configured such that, at some flow conditions,
the average ideal Mach number at the exhaust screen is about 0.8-1.1. Some example
embodiments may be configured such that, at some flow conditions, the average ideal Mach
number at the exhaust screen is about 0.9-1.0. Some example embodiments may be
configured such that, at some flow conditions, the average ideal Mach number at the exhaust
screen is about 0.85-1.15.
Although some example embodiments have been described in connection with
discharging exit flow stream 5 into by-pass flow path 4, it is within the scope of the
disclosure to direct exit flow stream 5 elsewhere. For example, some muffling devices
according to the present disclosure may be mounted at the engine pylon, the turbine rear
frame, and/or core nozzle/center bleed tube. Some example embodiments may be arranged to
direct exit flow stream 5 generally behind gas turbine engine assembly 10.
This written description uses examples to disclose the invention, including the best
mode, and also to enable any person skilled in the art to practice the invention, including
making and using any devices or systems and performing any incorporated methods. The
patentable scope of the invention is defined by the claims, and may include other examples
that occur to those skilled in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ from the literal language of
the claims, or if they include equivalent structural elements with insubstantial differences
from the literal languages of the claims.
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1fan flow stream
2bleed air
4 by-pass flow path
5 exit flow stream
10gas turbine engine assembly
12 core gas turbine engine
14 high-pressure compressor
16combustor
18 high-pressure turbine
20 low-pressure turbine
22 fan assembly
24fan blades
28 intake side
29 exhaust side
31 first rotor shaft
32second rotor shaft
40 bleed system
44 bleed flow conduit
45 bleed air valve
47bleed flow conduit length
49 muffling device length
50 muffling device
102 exhaust can
104exhaust screen
106 holes of exhaust screen 104
108 interior of exhaust can 102
110 inner flow conditioner
112 sidewall of inner flow conditioner 110
114downstream end wall of inner flow conditioner 110
116 interior of inner flow conditioner 110
118 inlet of inner flow conditioner 110
120 holes of sidewall 112 of inner flow conditioner 110
122 holes of downstream end wall 114 of inner flow conditioner 110
124central axis
126 upstream end wall of exhaust can 102
128sidewall of exhaust can 102
130diameter of exhaust can 102
132 upstream base diameter
134downstream base diameter
136 upstream base of inner flow conditioner 110
138downstream base of inner flow conditioner 110
14
200 muffling device
202exhaust can
204 exhaust screen
206 holes of exhaust screen 204
208 interior of exhaust can 202
210 inner flow conditioner
212 sidewall of inner flow conditioner 210
214downstream end wall of inner flow conditioner 210
216 interior of inner flow conditioner 210
218 inlet of inner flow conditioner 210
220holes of sidewall 212 of inner flow conditioner 210
222 holes of downstream end wall 214 of inner flow conditioner 210
226 upstream end wall of exhaust can 202
228sidewall of exhaust can 202
236upstream base of inner flow conditioner 210
238 downstream base of inner flow conditioner 210
300 muffling device
302 exhaust can
304exhaust screen
306 holes of exhaust screen 304
308 interior of exhaust can 302
310 inner flow conditioner
312 sidewall of inner flow conditioner 310
314 downstream end wall of inner flow conditioner 310
316 interior of inner flow conditioner 310
318 inlet of inner flow conditioner 310
320 holes of sidewall 312 of inner flow conditioner 310
322 hole sof downstream end wall 314 of inner flow conditioner 310
326upstream end wall of exhaust can 302
328 sidewall of exhaust can 302
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WECLAIM:
1. A muffling device (50), comprising:
an inner flow conditioner (110) comprising an inlet (118), the inlet (118) being
configured to convey a pressurized fluid flow into an inner flow conditioner interior (116),
the inner flow conditioner (110) comprising a plurality of inner flow conditioner holes (120,
122); and
an exhaust can (102) disposed substantially around the inner flow conditioner (110)
and arranged to receive the pressurized fluid flow via the inner flow conditioner holes (120,
122) into an exhaust can interior (108), the exhaust can (102) comprising an exhaust screen
(104) comprising a plurality of exhaust screen holes (106) arranged to discharge the
pressurized fluid flow from the exhaust can interior (108);
wherein the exhaust can interior (108) is substantially devoid of flow obstructions
between the plurality of inner flow conditioner holes (120, 122) and the exhaust screen holes
(106);
wherein a ratio of an effective flow area of the inner flow conditioner holes (120, 122)
to an effective flow area of the inlet (118) is about 0.7 to about 1.75; and
wherein a ratio of an effective flow area of the exhaust screen holes (106) to the
effective flow area of the inlet (118) is about 0.9 to about 2.8.
2. The muffling device (50) of claim 1, wherein the ratio of the effective flow area ofthe
inner flow conditioner holes (120, 122) to the effective flow area of the inlet (118) is about
0.75 to about 0.86.
3. The muffling device (50) of claim 1, wherein the ratio ofthe effective flow area ofthe
exhaust screen holes (106) to the effective flow area ofthe inlet (118) is about 1.0 to about
1.9.
4. The muffling device (50) of claim 1, wherein the ratio of the effective flow area ofthe
exhaust screen holes (106) to the effective flow area of the inlet (118) is about 2.6 to about
2.7.
5. The muffling device (50) of claim 1, wherein a ratio of a volume of the inner flow
conditioner interior (116) to a volume of the exhaust can interior (108) is about 0.06 to about
0.40.
16
6. The muffling device (50) of claim 1, wherein a ratio ofa volume of the inner flow
conditioner interior (116) to a volume of the exhaust can interior (108) is about 0.10 to about
0.22.
7. The muffling device (50) of claim 1, wherein a ratio of a volume ofthe inner flow
conditioner interior (116) to a volume of the exhaust can interior (108) is about 0.125 to
about 0.195.
8. The muffling device (50) of claim 1, wherein the exhaust screen (104) is outwardly
curved.
9. The muffling device (50) of claim 1, further comprising a bleed flow conduit (44)
operatively connected between the inlet (118) and a bleed air valve (45) configured to
selectively bleed a compressor (14) of a gas turbine engine (10) via the bleed flow conduit
(44).
10. The muffling device of claim 9, wherein a length of the exhaust can (102) is less than
about one third of the sum of the length of the exhaust can (102) and a length of the bleed
flow conduit (44).