Note: Descriptions are shown in the official language in which they were submitted.
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FLOW-CONTROL TECHNIQUE TO VECTOR BULK FLOW LEAVING A VANE
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No.
60/801,338, filed May 18, 2006.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0002] This invention was made with Government support under DAAD19-00-C-
0125 awarded by the Department of Defense. The Government has certain rights
in
this invention.
TECHNICAL FIELD
[0003] The present invention relates to a gas turbine engine and, more
particularly, to vanes for use in a fan section or a compressor section of the
engine.
BACKGROUND
[0004] Turbofan gas turbine engines typically include five major sections, for
example, a fan section, a compressor section, a combustor section, a turbine
section,
and an exhaust section. The fan section is positioned at the front, or "inlet"
section of
the engine, and includes a fan that induces air from the surrounding
environment into
the engine, and accelerates a fraction of this air toward the compressor
section. The
remaining fraction of air induced into the fan section is accelerated into and
through a
bypass plenum, and out the exhaust section.
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[0005] The compressor section, which may include one or more compressors,
raises the pressure of the air it receives from the fan section to a
relatively high level.
The compressed air then enters the combustor section, where a ring of fuel
nozzles
injects a steady stream of fuel. The injected fuel is ignited by a burner,
significantly
increasing the energy of the resulting hot, compressed gases, and the gases
then flow
into and through the turbine section to cause rotationally mounted turbine
blades to
rotate and generate energy. The gases exiting the turbine section are
exhausted from
the engine via the exhaust section, and the energy remaining in this exhaust
stream
aids the thrust generated by the air flowing through the bypass plenum.
[0006] To direct the flow of air out of the fan section or to direct the flow
of air
within the compressor, a guide vane assembly is typically disposed therein.
The
guide vane assembly includes variable geometry guide vanes that typically
extend
radially inward from the annular casing towards a hub. In many cases, the
guide
vanes are coupled to a plurality of actuators via unison rings, linkages, and
bell-
cranks, that, when moved, changes the positioning of the guide vanes to
thereby
control the direction and amount of airflow into downstream sections of the
engine.
[0007] Although the above-described assembly adequately controls airflow, it
suffers from certain drawbacks. For example, typically the guide vanes are
fixed in a
single position during aircraft operation or scheduled to be set at pre-
determined
positions based on engine speed; thus, they may not adequately respond to a
rapid
airflow change in the event a distortion is present in the compressor.
Additionally, the
engine may not operate as efficiently with the fixed guide vanes. Moreover,
the guide
vane assembly includes many components which may undesirably add weight and/or
cost to an aircraft.
[0008] Hence, there is a need for a guide vane assembly that includes guide
vanes
that respond to rapid changes in airflow. Additionally, there is a need for a
guide
vane assembly that has few components and that is relatively inexpensive to
implement. Furthermore, other desirable features and characteristics of the
present
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invention will become apparent from the subsequent detailed description and
the
appended claims, taken in conjunction with the accompanying drawings and the
foregoing technical field and background.
BRIEF SUMMARY
[0009] The present invention provides a guide vane assembly. In one
embodiment, and by way of example only, the inlet guide vane assembly includes
an
annular casing, and a plurality of vanes. The plurality of vanes is coupled to
and
extends radially inwardly from the annular casing. Each vane includes a first
wall, a
second wall, a leading edge, a first wall trailing edge, and a second wall
trailing edge.
The first and second walls are coupled at the leading edge and spaced apart to
define a
plenum therebetween. The first and second wall trailing edges are spaced apart
to
define a gap therebetween. The first wall trailing edge includes a lip
extending
therefrom toward the second wall, and the second wall trailing edge includes a
bulb
section extending along at least a portion of a length thereof. The second
wall trailing
edge is disposed at least partially inside the lip, wherein a substantial
entirety of the
vane between an outer surface of the second wall and an outer surface of the
bulb
portion is rounded.
[0010] In another embodiment, and by way of example only, the guide vane
assembly includes an annular casing and a plurality of vanes. The annular
casing
includes a manifold and a plurality of openings in communication with the
manifold.
The plurality of vanes is coupled to and extends radially inwardly from the
casing,
and each vane includes a first wall, a second wall, a leading edge, a first
wall trailing
edge, a second wall trailing edge, and a stem. The first and second walls are
coupled
at the leading edge and spaced apart to define a plenum therebetween. The
first and
second wall trailing edges are spaced apart to define a gap therebetween. The
first
wall trailing edge includes a lip extending therefrom toward the second wall,
and the
second wall trailing edge includes a bulb section extending along at least a
portion of
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a length thereof The second wall trailing edge is disposed at least partially
inside the
lip, wherein a substantial entirety of the vane between an outer surface of
the second
wall and an outer surface of the bulb portion is rounded. The stem is
configured to
be disposed in a corresponding opening of the manifold plurality of openings,
and
includes an aperture providing communication between the manifold and the
plenum.
[0011] In still another embodiment, the guide vane assembly includes an
annular
casing, a plurality of vanes, and an air source. The annular casing includes a
manifold
and a plurality of openings in communication with the manifold. The plurality
of
vanes is coupled to and extend radially inwardly from the annular casing and
defines
at least one flow passage therebetween. Each vane includes a first wall, a
second
wall, a leading edge, a first wall trailing edge, a second wall trailing edge,
and a stem.
The first and second walls are coupled at the leading edge and spaced apart to
define a
plenum therebetween. The first and second wall trailing edges are spaced apart
to
define a gap therebetween. The first wall trailing edge includes a lip
extending
therefrom toward the second wall, and the second wall trailing edge includes a
bulb
section extending along at least a portion of a length thereof. The second
wall trailing
edge is disposed at least partially inside the lip, wherein a substantial
entirety of the
vane between an outer surface of the second wall and an outer surface of the
bulb
portion is rounded. The stem is configured to be disposed in a corresponding
opening
of the manifold plurality of openings, and includes an aperture providing
communication between the manifold and the plenum. The air source is in flow
communication with the annular casing plenum and is configured to selectively
supply air thereto to thereby provide air to the vane plenum and vane gap such
that
when air flows through the flow passage in a first direction, air flowing
through the
vane gap redirects the flow passage air to flow in a second direction.
[0012] Other independent features and advantages of the preferred vane
assembly
will become apparent from the following detailed description, taken in
conjunction
with the accompanying drawings which illustrate, by way of example, the
principles
of the invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a cross section view of an exemplary gas turbine engine;
[0014] FIG. 2 is a cutaway view of an exemplary inlet guide vane assembly that
may be implemented into the fan module of FIG. 1;
[0015] FIG. 3 is an isometric view of an exemplary vane that may be
implemented into the inlet guide vane assembly shown in FIG. 2;
[0016] FIG. 4 is a cutaway view of the vane shown in FIG. 3;
[0017] FIG. 5 is a cross section view of the vane shown in FIG. 3; and
[0018] FIG. 6 is a close up view of a trailing section of the exemplary vane
of
FIG. 5.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0019] The following detailed description of the invention is merely exemplary
in
nature and is not intended to limit the invention or the application and uses
of the
invention. Specifically, although the figures and description describe an
inlet guide
vane assembly of a fan module, the invention may be implemented into other
sections
of an engine, such as in a compressor guide vane assembly. Furthermore, there
is no
intention to be bound by any theory presented in the preceding background of
the
invention or the following detailed description of the invention.
[0020] Turning now to the description and with reference first to FIG. 1, a
partial
cross section side view of a turbofan jet engine 100 is depicted. The turbofan
jet
engine 100 includes a fan module 110, a compressor module 120, a combustor and
turbine module 130 and an exhaust module 140. The fan module 110 is positioned
at
the front, or "inlet" section of the engine 100, and includes an inlet guide
vane
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assembly 106 that directs a primary airflow 202 (shown in FIG. 2) into the fan
module
110. The fan module 110 also includes a fan 108 that induces air from the
surrounding environment into the engine 100. The fan module 110 accelerates a
fraction of this air as the primary airflow 202 toward the compressor module
120, and
the remaining fraction is accelerated into and through a bypass 112, and out
the
exhaust module 140.
[0021] The compressor module 120 raises the pressure of the air it receives to
a
relatively high level. The compressor module 120 includes a low pressure
section 150
and a high pressure section 160 through which the primary airflow 202 (shown
in
FIG. 2) travels. The low pressure section 150 typically includes stages, each
of which
includes rotors 170 and guide vane assemblies 175. Each of the rotors 170 has
a
plurality of blades (not shown) and is rotationally mounted on a low pressure
shaft
190, which is driven by the low pressure turbine 116. As the rotors 170
rotate, the
blades force primary airflow 202 through each of the guide vane assemblies 175
in
subsequent sections. Each guide vane assembly 175 also includes a plurality of
vanes.
[0022] The high-pressure compressed air then enters the combustor and turbine
module 130, where a ring of fuel nozzles 114 (only one illustrated) injects a
steady
stream of fuel. The injected fuel is ignited by a burner (not shown), which
significantly increases the energy of the resulting high-pressure compressed
gases.
The high-energy compressed gases then flow first into a high pressure turbine
115 and
then a low pressure turbine 116, causing rotationally mounted turbine blades
118 on
each turbine 115, 116 to turn and generate energy. The energy generated in the
turbines 115, 116 is used to power other portions of the engine 100, such as
the fan
module 110 and the compressor module 120. The gases exiting the combustor and
turbine module 130 then leave the engine 100 via the exhaust module 140. The
energy remaining in the exhaust stream aids the thrust generated by the air
flowing
through the bypass 112.
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[0023] Turning now to FIG. 2, a cutaway view of an exemplary inlet guide vane
assembly 200 is shown. The inlet guide vane assembly 200 may be used in the
fan
module 110 as inlet guide vane assembly 106 or in the compressor module 120
for
guide vane assembly 175. In any case, the inlet guide vane assembly 200 is
configured to direct a primary airflow 202 through a flow passage in a desired
direction. In this regard, the guide vane assembly 200 includes an annular
casing 204
and, as briefly mentioned above, a plurality of vanes 206. The annular casing
204 has
a manifold 208 and a plurality of openings 210 (one of which is shown) formed
therein, and both are in flow communication with a non-illustrated secondary
air flow
source. The openings 210, which fluidly communicate with the manifold 208, are
configured to suitably receive the vanes 206.
[0024] Each vane 206, as shown in detail in FIGs. 3 and 4, includes an
airfoi1304,
a platform 306, and a stem 308. The platform 306 is configured to radially
contain
engine airflow and position the vane 206 in the primary flow path 202. The
stem 308
attaches the vane 206 to the annular casing 204 and includes one or more
apertures
310 formed therein that communicate with the annular casing manifold 208.
Although the stem 308 is shown with a cylinder 312 configuration machined
therein,
it will be appreciated that in other embodiments, any one of numerous other
shapes
suitable for attaching the vane 206 to the annular casing 204. Referring now
to FIGs.
3-6, the airfoi1304 has two walls 314, 316, a leading edge 320, and a trailing
section
324. The walls 314, 316 are spaced apart from one another to define a plenum
318
therebetween and are joined together at the leading edge 320. The plenum 318
is
configured to direct a secondary airflow 212 received from the stem aperture
310
therethrough. In some embodiments, standoffs 322 may be disposed in the plenum
318 to direct the secondary airflow 212 in a desired direction. The standoffs
322
extend between the two walls 314, 316 and may have any shape that affects the
secondary airflow 212 in a desired manner.
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[0025] Preferably, the walls 314, 316 and leading edge 320 are substantially
smooth so that the primary airflow 202 traveling from the leading edge 320
toward
the trailing section 324 flows substantially along the outer surface of the
walls 314,
316. In cases in which a change in primary airflow direction is desired, as
alluded to
above, the secondary air source provides secondary air to the annular casing
plenum
208, which travels through the vane plenum 318, and exits the trailing section
324.
[0026] The secondary airflow exits the vane plenum 318 through a gap 328
formed in the trailing section 324. With reference now to FIG. 6, a close up
view of
the trailing section 324 is provided. The gap 328 is defined by trailing edges
330, 332
that are formed on each of the walls 314, 316. To ensure that the secondary
airflow
212 suitably carries a desired portion of the primary airflow 202 therewith,
the trailing
edge 330 of the first wa11314 preferably extends past the trailing edge 332 of
the
second wa11316. Additionally, the first wall trailing edge 330 includes a lip
334 that
extends along substantially an entire length thereof and projects toward the
second
wa11316. The lip 334 may have a blunt edge, as shown in FIGs. 5 and 6, or
alternatively, may have a sharp edge. The second wall trailing edge 332
includes a
bulb portion 336 that extends the length thereof The bulb portion 336 is
disposed
inside of and is at least partially surrounded by the lip 334. To further
ensure that the
secondary airflow 212 affects the primary airflow 202 in a desired manner, a
substantial entirety of the vane 206 between an outer surface of the second
wa11316
and an outer surface of the bulb portion 336 is rounded. In another exemplary
embodiment, a substantial entirety of the vane 206 between an inner surface of
the
second wa11316 and inner surface of the bulb portion 336 may also be smooth.
[0027] During operation, the primary airflow 202 flows along the outer
surfaces
of the first and second walls 314, 316. Because of the features of the
trailing edge
section as described above, the primary airflow 202 "stays attached" to the
outer
surfaces walls 314, 316. When a portion of the primary airflow 202 flows
across the
gap 328 in the trailing section 324 of the vane 206, the secondary airflow 212
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interacts with the primary airflow 202. Consequently, the direction in which
the
primary airflow 202 travels is altered from a first direction to a second
direction. The
amount of directional change may be modified by adjusting the amount of air
supplied by the secondary air supply source to the secondary airflow 212.
Thus, if a
small amount of air is provided, the secondary airflow 212 will cause a slight
change
in primary airflow 202 direction. If a larger amount of air is supplied, the
change in
the primary airflow 202 direction will be more affected.
[0028] There has now been provided a guide vane assembly that is relatively
inexpensive and lightweight to implement. The guide vane assembly may be
retrofitted into currently existing gas turbine engines, or implemented in the
design of
new gas turbine engines. Additionally, the guide vane assembly redirects
primary
airflow by using a secondary airflow to interact therewith. Specifically, the
secondary airflow remains attached to the rounded surface of the bulb portion
of the
trailing edge by a Coanda effect, changing the flow separation point and lift
force
acting on each vane. The change in lift force redirects the primary airflow by
adding
a swirl component transverse thereto.
[0029] While the invention has been described with reference to a preferred
embodiment, it will be understood by those skilled in the art that various
changes may
be made and equivalents may be substituted for elements thereof without
departing
from the scope of the invention. In addition, many modifications may be made
to
adapt to a particular situation or material to the teachings of the invention
without
departing from the essential scope thereof. Therefore, it is intended that the
invention
not be limited to the particular embodiment disclosed as the best mode
contemplated
for carrying out this invention, but that the invention will include all
embodiments
falling within the scope of the appended claims.
