U.S. patent application number 14/743584 was filed with the patent office on 2015-12-24 for nacelle air scoop assembly.
The applicant listed for this patent is United Technologies Corporation. Invention is credited to John M. Feiereisen.
Application Number | 20150369065 14/743584 |
Document ID | / |
Family ID | 53716285 |
Filed Date | 2015-12-24 |
United States Patent
Application |
20150369065 |
Kind Code |
A1 |
Feiereisen; John M. |
December 24, 2015 |
NACELLE AIR SCOOP ASSEMBLY
Abstract
An air scoop assembly that may be for a nacelle of a turbofan
engine includes a surface defining at least in-part a primary
flowpath and a hood formed to the surface and projecting into the
primary flowpath. The hood includes a distal, leading, edge that is
irregular in shape thereby producing air vortices that shed from
the leading edge and co-extend in a downstream direction with an
airstream in the primary flowpath. The vortices are thereby
controlled such that air flow disruption and undesired resonance is
minimized or eliminated.
Inventors: |
Feiereisen; John M.; (South
Windsor, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Hartford |
CT |
US |
|
|
Family ID: |
53716285 |
Appl. No.: |
14/743584 |
Filed: |
June 18, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62013880 |
Jun 18, 2014 |
|
|
|
Current U.S.
Class: |
415/1 ;
415/144 |
Current CPC
Class: |
F05D 2260/60 20130101;
F01D 9/02 20130101; F02C 6/06 20130101; F02C 7/04 20130101; B64D
2241/00 20130101; B64C 7/02 20130101; F01D 25/24 20130101; F02K
3/075 20130101 |
International
Class: |
F01D 9/02 20060101
F01D009/02; F01D 25/24 20060101 F01D025/24 |
Claims
1. An air scoop assembly configured to mount to a surface defining
a primary flow path, the air scoop assembly comprising: a hood
having an irregular upstream edge and configured to project into
the primary flowpath.
2. The air scoop assembly set forth in claim 1, wherein the edge is
at least one vortex generator.
3. The air scoop assembly set forth in claim 2, wherein the edge is
scalloped.
4. The air scoop assembly set forth in claim 2 further comprising:
an air duct having an inlet defined at least by the surface and the
edge.
5. The air scoop assembly set forth in claim 4, wherein the air
duct defines a secondary flowpath in fluid communication with the
primary flowpath and for the intermittent flow of air from the
primary flowpath.
6. The air scoop assembly set forth in claim 5 further comprising:
a valve configured for the intermittent isolation of the secondary
flowpath.
7. The air scoop assembly set forth in claim 6, wherein the valve
includes a closed position and an open position and the at least
one vortex generator forms at least one vortices that breaks up any
coherent shedding off of air flow from the hood when the valve is
in the closed position.
8. The air scoop assembly set forth in claim 2, wherein the edge
has at least one apex projecting in an upstream direction and into
the primary flowpath.
9. The air scoop assembly set forth in claim 7, wherein the edge
has at least one apex projecting into an upstream direction and
into the primary flowpath.
10. The air scoop assembly set forth in claim 9, wherein the hood
is flush with the surface.
11. The air scoop assembly set forth in claim 9, wherein the hood
projects transversely into the primary flowpath and outward from
the surface.
12. The air scoop assembly set forth in claim 9, wherein the
surface is carried by a nacelle.
13. The air scoop assembly set forth in claim 8, wherein the apex
projects upstream by a downstream-most portion of the edge by a
distance that is about twice a thickness of the hood.
14. The air scoop assembly set forth in claim 8, wherein the at
least one apex is spaced from a next adjacent apex by a distance
that is about one fifth to about one half a height of the hood.
15. A nacelle for a gas turbine engine comprising: a fan cowling
concentrically disposed to an engine axis and surrounding a fan
section of the gas turbine engine; a core cowling concentrically
disposed to the engine axis and located downstream of the fan
section with an annular air bypass flowpath defined between and by
the fan and core cowlings; and a hood formed to the core cowling
and projecting into the bypass flowpath, the hood including a
leading edge that includes at least one apex projecting in an
upstream direction and acting as at least one vortex generator.
16. The nacelle set forth in claim 15 further comprising: an air
duct having an inlet defined at least by the core cowling and the
edge; and wherein the air duct defines a secondary flowpath in
fluid communication with the bypass flowpath and for the
intermittent flow of air from the bypass flowpath.
17. The nacelle set forth in claim 16 further comprising: a valve
in the air duct for the intermittent isolation of the secondary
flowpath; and wherein the valve includes a closed position and an
open position and the at least one vortex generator forms at least
one vortex that breaks up any coherent shedding off of air flow
from the hood when the valve is in the closed position.
18. The nacelle set forth in claim 15, wherein the hood is flush
with the core cowling.
19. The nacelle set forth in claim 15, wherein the hood projects
transversely into the bypass flowpath and radially outward from the
core cowling.
20. A method of operating an air scoop assembly comprising the
steps of: substantially closing the air scoop assembly having a
hood that projects into a primary air flowpath; and forming at
least one air vortex that stems from an irregular leading edge of a
hood of the air scoop assembly and extends in a substantially
downstream direction thereby minimizing disruption of airstreams in
the primary air flowpath.
Description
[0001] This application claims priority to U.S. Patent Appln. No.
62/013,880 filed Jun. 18, 2014.
BACKGROUND
[0002] The present disclosure relates to gas turbine engines, and
more particularly to an air scoop assembly in a nacelle of the gas
turbine engine and method of operating.
[0003] Air scoops are known to project into a primary air flowpath
for redirecting a portion of the air flow to serve a particular
purpose such as cooling of components in a remote region. One
example of such air scoops are those that project into a bypass air
flowpath of a nacelle for a turbofan engine often called ram
scoops. Unfortunately, the air scoops are known to disrupt
efficient airstream flow. This disruption is further aggravated
where air scoop assemblies include valves that intermittently limit
or prevent diversion of air flow through the air scoop
assembly.
[0004] For example, with a valve of the air scoop assembly closed,
flow spills around the ram scoop and tends to separate off a
leading edge of the scoop or hood. With traditional, uniform, edge
contours, this separation may result in the shedding of a coherent
vortex spanning the full width of the ram scoop. This type of
shedding may couple with the natural frequency of the ducting
between the ram scoop inlet lip and the valve controlling the flow.
This resonance may produce significant unsteady pressures resulting
in elevated noise and/or elevated unsteady stresses in surrounding
structures.
SUMMARY
[0005] An air scoop assembly configured to mount to a surface
defining a primary flow path, the assembly according to one,
non-limiting embodiment of the present disclosure includes a hood
having an irregular upstream edge and configured to project into
the primary flowpath.
[0006] Additionally to the foregoing embodiment, the edge is at
least one vortex generator.
[0007] In the alternative or additionally thereto, in the foregoing
embodiment, the edge is scalloped.
[0008] In the alternative or additionally thereto, in the foregoing
embodiment the air scoop assembly includes an air duct having an
inlet defined at least by the surface and the edge.
[0009] In the alternative or additionally thereto, in the foregoing
embodiment, the air duct defines a secondary flowpath in fluid
communication with the primary flowpath and for the intermittent
flow of air from the primary flowpath.
[0010] In the alternative or additionally thereto, in the foregoing
embodiment the air scoop assembly includes a valve configured for
the intermittent isolation of the secondary flowpath.
[0011] In the alternative or additionally thereto, in the foregoing
embodiment, the valve includes a closed position and an open
position and the at least one vortex generator forms at least one
vortex that breaks up any coherent shedding off of air flow from
the hood when the valve is in the closed position.
[0012] In the alternative or additionally thereto, in the foregoing
embodiment, the edge has at least one apex projecting in an
upstream direction and into the primary flowpath.
[0013] In the alternative or additionally thereto, in the foregoing
embodiment, the edge has at least one apex projecting into an
upstream direction and into the primary flowpath.
[0014] In the alternative or additionally thereto, in the foregoing
embodiment, the hood is flush with the surface.
[0015] In the alternative or additionally thereto, in the foregoing
embodiment, the hood projects transversely into the primary
flowpath and outward from the surface.
[0016] In the alternative or additionally thereto, in the foregoing
embodiment, the surface is carried by a nacelle.
[0017] In the alternative or additionally thereto, in the foregoing
embodiment, the apex projects upstream by a downstream-most portion
of the edge by a distance that is about twice a thickness of the
hood.
[0018] In the alternative or additionally thereto, in the foregoing
embodiment, the at least one apex is spaced from a next adjacent
apex by a distance that is about one fifth to about one half a
height of the hood.
[0019] A nacelle for a gas turbine engine according to another,
non-limiting, embodiment includes a fan cowling concentrically
disposed to an engine axis and surrounding a fan section of the gas
turbine engine; a core cowling concentrically disposed to the
engine axis and located downstream of the fan section with an
annular air bypass flowpath defined between and by the fan and core
cowlings; and a hood formed to the core cowling and projecting into
the bypass flowpath, the hood including a leading edge that
includes at least one apex projecting in an upstream direction and
acting as at least one vortex generator.
[0020] Additionally to the foregoing embodiment, the nacelle
includes an air duct having an inlet defined at least by the core
cowling and the edge; and wherein the air duct defines a secondary
flowpath in fluid communication with the bypass flowpath and for
the intermittent flow of air from the bypass flowpath.
[0021] In the alternative or additionally thereto, in the foregoing
embodiment the nacelle includes a valve in the air duct for the
intermittent isolation of the secondary flowpath; and wherein the
valve includes a closed position and an open position and the at
least one vortex generator forms at least one vortex that breaks up
any coherent shedding off of air flow from the hood when the valve
is in the closed position.
[0022] In the alternative or additionally thereto, in the foregoing
embodiment, the hood is flush with the core cowling.
[0023] In the alternative or additionally thereto, in the foregoing
embodiment, the hood projects transversely into the bypass flowpath
and radially outward from the core cowling.
[0024] A method of operating an air scoop assembly according to
another, non-limiting, embodiment includes the steps of
substantially closing the air scoop assembly having a hood that
projects into a primary air flowpath; and forming at least one air
vortex that stems from an irregular leading edge of a hood of the
air scoop assembly and extends in a substantially downstream
direction thereby minimizing disruption of airstreams in the
primary air flowpath.
[0025] The foregoing features and elements may be combined in
various combination without exclusivity, unless expressly indicated
otherwise. These features and elements as well as the operation
thereof will become more apparent in light of the following
description and the accompanying drawings. It should be understood,
however, the following description and figures are intended to
exemplary in nature and non-limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Various features will become apparent to those skilled in
the art from the following detailed description of the disclosed
non-limiting embodiments. The drawings that accompany the detailed
description can be briefly described as follows:
[0027] FIG. 1 is a schematic cross section of a gas turbine
engine;
[0028] FIG. 2 is a partial perspective view of the engine viewing
in an upstream direction;
[0029] FIG. 3 is a side view of an air scoop assembly;
[0030] FIG. 4 is a perspective view of a hood of the air scoop
assembly; and
[0031] FIG. 5 is a cross section of a leading edge of the hood
taken along line 5-5 of FIG. 4.
DETAILED DESCRIPTION
[0032] FIG. 1 schematically illustrates a gas turbine engine 20
disclosed as a two-spool turbo fan that generally incorporates a
fan section 22, a compressor section 24, a combustor section 26 and
a turbine section 28. The fan section 22 drives air along a bypass
or primary flowpath 29 while the compressor section 24 drives air
along a core flowpath for compression and communication into the
combustor section 26 then expansion through the turbine section 28.
Although depicted as a turbofan in the disclosed non-limiting
embodiment, it should be understood that the concepts described
herein are not limited to use with turbofans as the teachings may
be applied to other types of turbine engine architecture such as
turbojets, turboshafts, three-spool turbofans, land-based turbine
engines, and others.
[0033] The engine 20 generally includes a low spool 30 and a high
spool 32 mounted for rotation about an engine axis A via several
bearing structures 38 and relative to a static engine case 36. The
low spool 30 generally includes an inner shaft 40 that
interconnects a fan 42 of the fan section 22, a low pressure
compressor 44 ("LPC") of the compressor section 24 and a low
pressure turbine 46 ("LPT") of the turbine section 28. The inner
shaft 40 drives the fan 42 directly, or, through a geared
architecture 48 to drive the fan 42 at a lower speed than the low
spool 30. An exemplary reduction transmission may be an epicyclic
transmission, namely a planetary or star gear system.
[0034] The high spool 32 includes an outer shaft 50 that
interconnects a high pressure compressor 52 ("HPC") of the
compressor section 24 and a high pressure turbine 54 ("HPT") of the
turbine section 28. A combustor 56 of the combustor section 26 is
arranged between the HPC 52 and the HPT 54. The inner shaft 40 and
the outer shaft 50 are concentric and rotate about the engine axis
A. Core airflow is compressed by the LPC 44 then the HPC 52, mixed
with the fuel and burned in the combustor 56, then expanded over
the HPT 54 and the LPT 46. The LPT 46 and HPT 54 rotationally drive
the respective low spool 30 and high spool 32 in response to the
expansion.
[0035] In one non-limiting example, the gas turbine engine 20 is a
high-bypass geared aircraft engine. In a further example, the gas
turbine engine 20 bypass ratio is greater than about six (6:1). The
geared architecture 48 can include an epicyclic gear train, such as
a planetary gear system or other gear system. The example epicyclic
gear train has a gear reduction ratio of greater than about 2.3:1,
and in another example is greater than about 2.5:1. The geared
turbofan enables operation of the low spool 30 at higher speeds
that can increase the operational efficiency of the LPC 44 and LPT
46 and render increased pressure in a fewer number of stages.
[0036] A pressure ratio associated with the LPT 46 is pressure
measured prior to the inlet of the LPT 46 as related to the
pressure at the outlet of the LPT 46 prior to an exhaust nozzle of
the gas turbine engine 20. In one non-limiting example, the bypass
ratio of the gas turbine engine 20 is greater than about ten
(10:1); the fan diameter is significantly larger than the LPC 44;
and the LPT 46 has a pressure ratio that is greater than about five
(5:1). It should be understood; however, that the above parameters
are only exemplary of one example of a geared architecture engine
and that the present disclosure is applicable to other gas turbine
engines including direct drive turbofans.
[0037] In one non-limiting example, a significant amount of thrust
is provided by the bypass flowpath 29 due to the high bypass ratio.
The fan section 22 of the gas turbine engine 20 is designed for a
particular flight condition--typically cruise at about 0.8 Mach and
about 35,000 feet (10,668 meters). This flight condition, with the
gas turbine engine 20 at its best fuel consumption, is also known
as Thrust Specific Fuel consumption (TSFC). TSFC is an industry
standard parameter of fuel consumption per unit of thrust.
[0038] Fan Pressure Ratio is the pressure ratio across a blade of
the fan section 22 without consideration of the effect of a fan
exit guide vane assembly 58 located downstream of the fan 42 (also
see FIG. 2). The low Fan Pressure Ratio according to one,
non-limiting, example of the gas turbine engine 20 is less than
1.45:1. Low Corrected Fan Tip Speed is the actual fan tip speed
divided by an industry standard temperature correction of
(T/518.7.sup.0.5), where "T" represents the ambient temperature in
degrees Rankine. The Low Corrected Fan Tip Speed according to one
non-limiting example of the gas turbine engine 20 is less than
about 1150 fps (351 m/s).
[0039] Referring to FIGS. 1 and 2, a nacelle assembly 60 of the
turbine engine 20 has core cowling 62, a fan cowling 64 and a pylon
66. The core and fan cowlings 62, 64 are generally concentric to
the engine axis A with the core cowling 62 generally supporting the
core engine and surrounding the engine sections 24, 26, 28. The fan
cowling 64 is spaced radially outward from the core cowling 62 and
surrounds the fan 42 and guide vane assembly 58. The annular bypass
flow path 29 is defined between and by the core and fan cowlings
62, 64. The pylon 66 may be attached to both cowlings 62, 64 and
generally supports and attaches the entire engine 20 to, for
example, an aircraft (not shown).
[0040] Referring to FIGS. 1 through 3, an annular engine cavity 68
is located radially between and may be defined by the core cowling
62 and the inner engine case 36. Various engine components (not
shown) may be generally located in the cavity 68 and may require
cooling by a ventilation or air cooling system 70 through a series
of tube and hoses directed to the component and/or otherwise
ventilate the cavity 68 to prevent the accumulation of fumes.
Cooling system 70 may include an air scoop assembly 72 having a
hood 74 mounted to the core cowling 62 (as one example) and
projecting into the bypass flowpath 29 for receipt of a secondary
airflow. In some examples of the cooling system 70, the amount of
secondary airflow is dependent mainly upon the pressure difference
between the bypass flowpath 29 and the ambient air, and other
systems may include control logic with associated flow control
valve(s).
[0041] One, non-limiting, example of such an air cooling system 70,
is an Active Clearance Control (ACC) cooling system 70 that assists
in the control of a blade tip clearance between the engine case 36
and the tips of the rotating blades of the turbine section 28. More
specifically, the ACC cooling system 70 adjusts cooling flow to the
engine case 36 thereby controlling thermal expansion of the case
relative to centrifugal and thermal expansion of the turbine rotor
thereby minimizing and/or controlling the blade tip clearance
throughout varying engine operating conditions.
[0042] The air scoop assembly 72 of the ACC cooling system 70
includes the hood 74, a duct 76 defining a secondary air flowpath
78, and a flow control device or at least one valve 80 that
intersects the duct 76 for controlling the amount of secondary air
flow. The hood 74 has a contoured or scalloped leading edge 82
that, with a radially outward facing surface 84 of the core cowling
62, defines an inlet 86 of the secondary air flowpath 78. It is
further contemplated and understood that the air scoop assembly 72
may be generally mounted on any surface that defines at least
in-part a primary air flowpath and where the retrieval of a
secondary air flow is required.
[0043] In operation, and with the flow control device 80 in a
substantially open position, bypass air flows generally in an
axially downstream direction (see the bypass airstreams shown as
arrows 90 in FIG. 3) along the bypass flowpath 29. A portion of
this bypass air is scooped-up by the hood 74 of the air scoop
assembly 72 and flows through or along the secondary air flowpath
78. With the flow control device 80 substantially open, no (or
minimal) air vortices are created about the hood which could hinder
efficient flow of the bypass airstreams 90. Absent the features of
the present disclosure, with the flow control device closed or
substantially closed, no (or minimal) secondary air flows through
the secondary air flowpath and the hood of the air scoop assembly
may function more as an airstream obstruction in the bypass
flowpath. As such and in more traditional designs, air vortices or
disturbances may be created that undesirably disrupt the bypass
airstreams 90, reduce airflow efficiency, and lead to undesired
resonance that may produce significant unsteady pressures resulting
in elevated noise and elevated unsteady stresses in surrounding
structures, if not properly controlled.
[0044] Referring to FIGS. 3 and 4, the irregular or scalloped shape
of the leading edge 82 of the hood 74 generally functions as a
plurality of vortex generators that create, controlled, air
vortices 92 generally when the flow control device 80 is closed,
and which stem from the leading edge 82 of the hood 74 and
generally co-extend in the downstream direction with the bypass
airstreams 90 thereby minimizing any disruption of the bypass air
flow. That is, with the flow control device 80 generally closed,
there is a continuous shedding of streamwise vorticity. The
"continuous shedding" is desirable over discontinuous or periodic
shedding because it eliminates the production of undesired
resonance that produce excessive noise in the duct and stress upon
surrounding structure. That is, the irregular or non-uniform edge
82 avoids the tendancy to shed a full-width coherent vortex and
avoids any coupling with the natural frequency of the cowlings 62,
64. In addition to breaking up any full-width coherent vortex, with
the valve 80 closed, the non-uniform edge 82 acts as vortex
generators in the flow spilling around the edge, shedding
continuous, streamwise, vorticity and reducing any flow separation
in the bypass air flowpath 29 downstream of the hood 74. It is
further understood and contemplated that the irregular shape of the
leading edge may not be scalloped but may take the form of any
variety of shapes that may produce air vortices as described.
[0045] Referring to FIGS. 4 and 5, the irregular shape of the
leading edge 82 may be a plurality of scallops 94 (i.e. each
scallop generally being one vortex generator). Each scallop 94
meets the next adjacent scallop at an apex or convex portion 96
that generally projects and substantially faces in an upstream
direction, and which contributes toward the shedding of the air
vortices 92. Each apex 96 is spaced from the next adjacent apex by
a distance 100. Each scallop 94 also has a concave portion 98 that
substantially faces in the upstream direction and is generally
spaced axially (with respect to the engine axis A) from the apex 96
by a distance 102. The hood 74 has a width 104 measured between the
joinder(s) of the hood 74 to the surface 84 of the core cowling 62,
and a height 106 that is generally the maximum projection of the
hood into the bypass air flowpath 29 (i.e. maximum radial distance
from the surface 84 to the hood 74). The width 104 is substantially
greater than the height 106, and the height 106 is generally two to
five times greater than the distance 100 between apexes 96.
[0046] Axially downstream of the leading edge 82, the hood 74 has a
general thickness 108 and the concave portion 98 may have a
parabolic shaped cross section that generally begins where the hood
has the thickness 108 and projects upstream to a vertex by a
distance 110 that may be substantially equal to thickness 108. The
apex or convex portion 96 may have a parabolic shaped cross section
similar to the concave portion 98 but generally more pointed (i.e.
more tapered). The distance 102 between the apex 96 and the concave
portion 98 may be about equal to twice the thickness 108.
[0047] It is understood that relative positional terms such as
"forward," "aft," "upper," "lower," "above," "below," and the like
are with reference to the normal operational attitude and should
not be considered otherwise limiting. It is also understood that
like reference numerals identify corresponding or similar elements
throughout the several drawings. It should be understood that
although a particular component arrangement is disclosed in the
illustrated embodiment, other arrangements will also benefit.
Although particular step sequences may be shown, described, and
claimed, it is understood that steps may be performed in any order,
separated or combined unless otherwise indicated and will still
benefit from the present disclosure.
[0048] The foregoing description is exemplary rather than defined
by the limitations described. Various non-limiting embodiments are
disclosed; however, one of ordinary skill in the art would
recognize that various modifications and variations in light of the
above teachings will fall within the scope of the appended claims.
It is therefore understood that within the scope of the appended
claims, the disclosure may be practiced other than as specifically
described. For this reason, the appended claims should be studied
to determine true scope and content.
* * * * *