U.S. patent application number 13/746277 was filed with the patent office on 2017-10-19 for gas turbine engine nozzle including housing having scalloped root regions.
This patent application is currently assigned to The Boeing Company. The applicant listed for this patent is The Boeing Company. Invention is credited to David F. Cerra, Lie-Mine Gea, Leonard J. Hebert, Donald E. Robinson, Robert H. Willie.
Application Number | 20170298868 13/746277 |
Document ID | / |
Family ID | 51206642 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170298868 |
Kind Code |
A9 |
Cerra; David F. ; et
al. |
October 19, 2017 |
GAS TURBINE ENGINE NOZZLE INCLUDING HOUSING HAVING SCALLOPED ROOT
REGIONS
Abstract
A gas turbine engine exhaust nozzle comprises a housing having
an aft end that terminates in a row of chevrons. At least one
surface of the housing has scalloped root regions proximate bases
of adjacent chevrons. The scalloped root regions have a reduced
thickness relative to the rest of the aft end.
Inventors: |
Cerra; David F.; (Bellevue,
WA) ; Gea; Lie-Mine; (Irvine, CA) ; Willie;
Robert H.; (Bothell, WA) ; Hebert; Leonard J.;
(Kirkland, WA) ; Robinson; Donald E.; (Mercer
Island, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company |
Chicago |
IL |
US |
|
|
Assignee: |
The Boeing Company
Chicago
IL
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20140202164 A1 |
July 24, 2014 |
|
|
Family ID: |
51206642 |
Appl. No.: |
13/746277 |
Filed: |
January 21, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12483424 |
Jun 12, 2009 |
8356468 |
|
|
13746277 |
|
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|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2240/14 20130101;
F02K 1/34 20130101 |
International
Class: |
F02K 1/34 20060101
F02K001/34 |
Claims
1. A gas turbine engine exhaust nozzle, comprising a housing having
an aft end that terminates in a row of chevrons, at least one
surface of the housing having scalloped root regions proximate
bases of adjacent chevrons, the scalloped root regions having a
reduced thickness relative to the rest of the aft end.
2. The nozzle of claim 1, wherein the at least one surface includes
an interior surface of the housing.
3. The nozzle of claim 1, wherein the at least one surface includes
an exterior surface of the housing.
4. The nozzle of claim 1, wherein the housing has a thickness that
varies in a cross-sectional plane drawn through the scalloped root
regions.
5. The nozzle of claim 1, wherein the scalloped root regions are
generally laterally displaced from an axis extending longitudinally
along the surface of the nozzle and through tips of adjacent
chevrons, and extend from the bases of the chevrons.
6. The nozzle of claim 1, wherein the row of chevrons extends
entirely about the aft end of the housing.
7. A gas turbine engine comprising a nozzle, the nozzle including a
housing having an aft end that terminates in a row of chevrons, at
least one surface of the housing having scalloped root regions
proximate bases of adjacent chevrons, thickness of the housing
reduced in a cross-sectional plane drawn through the scalloped root
regions.
8. The engine of claim 7, wherein the at least one surface includes
an interior surface of the housing.
9. The engine of claim 7, wherein the at least one surface includes
an exterior surface of the housing.
10. The engine of claim 7, wherein the row of chevrons extends
entirely about the aft end of the housing.
11. The engine of claim 7, wherein the scalloped root regions are
generally laterally displaced from an axis extending longitudinally
along the surface of the nozzle and through tips of adjacent
chevrons, and extend from the bases of the chevrons
12. The engine of claim 7, wherein the engine is a turbofan
engine.
13. An aircraft comprising a propulsion system including at least
one gas turbine engine, each engine including a nozzle having a
housing, the housing having an aft end that terminates in a row of
chevrons, at least one surface of the housing having scalloped root
regions proximate bases of adjacent chevrons, the scalloped root
regions having a reduced thickness relative to the rest of the aft
end.
14. The aircraft of claim 13, wherein the at least one surface
includes an interior surface of the housing.
15. The aircraft of claim 13, wherein the at least one surface
includes an exterior surface of the housing
16. The aircraft of claim 13, wherein each gas turbine engine is a
turbofan engine.
17. The aircraft of claim 13, wherein the chevrons are configured
to decrease nozzle drag coefficient.
Description
[0001] This is a continuation of U.S. Ser. No. 12/483,424 filed 12
Jun. 2009, now U.S. Pat. No. 8,356,468.
BACKGROUND
[0002] Aircraft engines have been made quieter as a result of
advanced high bypass ratio engines. High bypass ratio engines
derive a substantial fraction of their total thrust from bypass air
which is propelled around the core of the engine by an
engine-driven forwardly mounted fan. This approach results in less
engine noise than pure turbojet engines or low bypass ratio
engines.
[0003] One approach to further reducing engine noise is to increase
the amount of mixing between the high velocity gases exiting the
engine, and the surrounding freestream air. In that regard, the use
of geometric structures known as chevrons may reduce low-frequency
noise by increasing the rate at which the engine flow streams mix
with the surrounding freestream air in the aft region of the
nozzle. However, in some circumstances existing chevron designs may
increase the drag of the duct, thereby decreasing engine
efficiency.
SUMMARY
[0004] According to an embodiment herein, a gas turbine engine
exhaust nozzle comprises a housing having an aft end that
terminates in a row of chevrons. At least one surface of the
housing has scalloped root regions proximate bases of adjacent
chevrons. The scalloped root regions have a reduced thickness
relative to the rest of the aft end.
[0005] According to another embodiment herein, a gas turbine engine
comprises a nozzle including a housing. An aft end of the housing
terminates in a row of chevrons. At least one surface of the
housing has scalloped root regions proximate bases of adjacent
chevrons. Thickness of the housing is reduced in a cross-sectional
plane drawn through the scalloped root region.
[0006] According to another embodiment herein, an aircraft
comprises a propulsion system including at least one gas turbine
engine. Each engine includes a nozzle having a housing. The housing
has an aft end that terminates in a row of chevrons. At least one
surface of the housing has scalloped root regions proximate bases
of adjacent chevrons. The scalloped root regions have a reduced
thickness relative to the rest of the aft end.
[0007] These features and functions may be achieved independently
in various embodiments or may be combined in other embodiments.
Further details of the embodiments can be seen with reference to
the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an illustration of a gas turbine engine.
[0009] FIG. 2 is an illustration of an aircraft including gas
turbine engines.
[0010] FIG. 3A is an illustration of a gas turbine engine
nozzle.
[0011] FIG. 3B is an illustration of a scalloped chevron gas
turbine engine nozzle surface.
[0012] FIG. 3C is an illustration of a section of a scalloped gas
turbine engine chevron nozzle.
[0013] FIG. 4 is an illustration of a scalloped chevron gas turbine
engine nozzle surface.
[0014] FIG. 5 is an illustration of a scalloped chevron gas turbine
engine nozzle surface.
[0015] FIG. 6 is an illustration of a method of operating a gas
turbine engine of an aircraft.
DETAILED DESCRIPTION
[0016] A gas turbine engine exhaust nozzle herein includes a
housing having an aft end that terminates in a row of chevrons.
Chevrons generally include certain types of serrations on the
nozzle lip, typically, triangular or sinusoidal in shape having
some curvature in the lengthwise cross-section, which slightly
immerses them in the adjacent flow. A chevron may project either
inwardly or outwardly, by an amount that is on the order of the
upstream boundary layer thickness on the inner or outer surface,
respectively. In general, the chevron planform shape may also be
trapezoidal or rectangular.
[0017] The chevrons define a root region proximate the base of
adjacent chevrons. Portions of an interior surface of the housing,
or an exterior surface of the housing, or portions of both
surfaces, are removed proximate the root regions of the chevrons to
define regions referred to herein as "scalloped" root regions. Some
or all of the root regions may be scalloped. In some embodiments, a
result of the scalloped root regions is that the thickness of the
housing varies in a cross-sectional plane drawn through the root
regions of the housing.
[0018] FIG. 3A illustrates an embodiment of a gas turbine engine
nozzle 300 including an annular housing 302 having a length which
extends along a central longitudinal axis 310 and comprising an
interior surface 312 and an exterior surface 314. An aft end of the
housing terminates in a row of chevrons 320. Each chevron 320 has a
tip 324 and a base 326. The chevrons 324 define root regions 322
proximate the bases 326.
[0019] In some embodiments, the row of chevrons 320 encompasses the
complete annulus of the aft end of the housing 302, while in other
embodiments the row of chevrons 320 may encompass only a portion of
the annulus of the housing 302. In the embodiment of FIG. 3A, the
various chevrons 320 are substantially uniform in size and shape.
In other embodiments, the various chevrons may vary in size and
shape, e.g., to reduce noise in selected directions.
[0020] In the embodiment of FIG. 3A, the surface of the annular
housing 302 converges toward the longitudinal axis 310 proximate
the aft end of the housing 302, such that the diameter of the
housing 302 decreases progressively toward the aft end of the
housing 302. In some embodiments, the row of chevrons 320
essentially follows the contoured surface of the housing 302 such
that each of the chevrons 320 lies in a plane that intersects the
longitudinal axis 310.
[0021] FIG. 3B illustrates an embodiment in which at least a
portion of at least one of the interior surface 312 and the
exterior surface 314 is scalloped proximate the root region 322 of
a chevron 320. Portions of the root regions 322 are removed to
define scalloped surface areas in the root regions 322. The
scalloped root regions 322 in FIG. 3B are depicted by contoured
lines analogous to topographical lines on a map. The scalloped root
regions are generally laterally displaced from an axis 340
extending longitudinally along the surface 302 of the nozzle 300
and through the tip 324 of adjacent chevrons 320, and extend from
the base 326 of the chevron. In some embodiments, the chevrons
measure between 10 centimeters and 60 centimeters from the base to
the tip, and the scalloped root regions 322 measure between
approximately 5 and 75 centimeters in width and 5 and 90
centimeters in length. More generally, however, the specific
measurements may vary both as a function of engine size and as a
function of engine load.
[0022] As illustrated in FIG. 3c, a result of the scalloped root
regions 322 is that the thickness of the annular housing 302 varies
in a cross-sectional plane drawn through the root regions 322 of
the housing 302. The thickness of the housing 302 is depicted by
contour lines 350 and 352, which follow the interior surface 312 of
housing 302 and the exterior surface 314 of housing 302,
respectively. The thickness of the housing 302 varies between a
maximum thickness at a point along a longitudinal axis 354
extending through the tip 324 of the chevron 320 to a minimum at a
point along a longitudinal axis 356 extending through the base 326
of the chevron. In some embodiments, the thickness of the housing
302 varies between a maximum thickness of 2.5 centimeters and a
minimum thickness of 0.25 centimeters. More generally, however, the
thickness of the housing 302 varies both as a function of the
engine size and as a function of engine load.
[0023] FIG. 4 is a schematic, perspective line view of a scalloped
chevron nozzle surface. The scalloped surface is represented by
solid contour lines. The scalloped root region is indicated
generally by reference numeral 322. The contour lines 410, 412,
414, 416, 418, 420, 422, and 424 represent lateral cross-section
contour lines at various positions along the longitudinal axis 356
of the housing 302. The first contour line 410 represents a lateral
cross-section taken outside the scalloped root region 322. In this
region the contour lines are coextensive. However, the contour
lines diverge as they approach the base 326 of the chevron. Thus,
the surfaces begin to diverge when the contour line 412 crosses the
scalloped region 322. Successive contour lines 414, 416, 418, show
increasing greater divergence between the surface contours. The
divergence is at a maximum along the longitudinal axis 356 that
extends through the base 326 of the chevron and the contour lines
converge at a point along a longitudinal axis 354 extending through
the tip 324 of the chevron.
[0024] FIG. 5 is a schematic, perspective line view of a scalloped
chevron nozzle surface. In FIG. 5, the scalloped surface is
indicated by solid contour lines. The scalloped root region is
indicated generally by reference numeral 322. The contour lines
510, 512, 514 are taken in a longitudinal direction, rather than a
lateral direction. Thus, the contour lines 510, 514, taken along a
longitudinal axis through the peak 324 of a chevron are
substantially coextensive, indicating that the surfaces are of
substantially equal thicknesses along those axes. By contrast, the
contour lines 512, taken along a longitudinal axis through the base
326 of a chevron diverge as the lines approach the base 326,
illustrating the contoured surface of a scalloped chevron root
region 322.
[0025] FIGS. 4 and 5 also illustrate the differences between
housing having a scalloped surface and a conventional,
constant-thickness housing. In both figures, the scalloped surface
is represented by solid lines, and the conventional surface is
indicated by dashed lines.
[0026] FIG. 1 is an illustration of a gas turbine engine 10
including an example of a jet engine nozzle 20. The nozzle 20
includes a core flow duct 40, and a fan flow duct 30 arranged
annularly around the core flow duct 40. During operation of the gas
turbine engine 10, engine core flow is directed through the core
flow duct 40, and fan air passes through the fan flow duct 30. An
exit aperture of the core flow duct 40 may include core flow
chevrons 45, and an exit aperture of the fan flow duct 30 may
include fan flow chevrons 35.
[0027] FIG. 2 is a schematic illustration of a commercial jet
transport aircraft 200 including a fuselage 201, wings 202, and a
propulsion system 203. The propulsion system 203 includes at least
one gas turbine engine 206. In some embodiments, each gas turbine
engine 206 may be a turbofan engine. Each engine 206 is housed in a
nacelle 204, which includes an inlet 205 and a nozzle 220. Each
nozzle 220 includes chevrons having scalloped root regions to
reduce the coefficient of drag associated with the nozzles 220.
[0028] Other embodiments of an aircraft herein may include a
different number of engines and/or engines carried by different
portions of the aircraft, along with nozzles herein that are
tailored to the particular installation.
[0029] FIG. 6 illustrates a method of operating an engine 206 of
the jet. At operation 610, an exhaust flow is generated. At
operation 615, the exhaust flow is directed through the exhaust
nozzle have at least one scalloped root region. The scalloped root
regions may decrease the drag coefficient of the nozzle, thereby
increasing efficiency of the engine 206. Alternatively, or in
addition, the scalloped root regions may tailor airflow through the
engine 206.
* * * * *