U.S. patent application number 13/716959 was filed with the patent office on 2014-06-19 for fan with integral shroud.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to Jesse M. Chandler, Brian D. Merry, Gabriel L. Suciu.
Application Number | 20140169972 13/716959 |
Document ID | / |
Family ID | 50931097 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140169972 |
Kind Code |
A1 |
Suciu; Gabriel L. ; et
al. |
June 19, 2014 |
FAN WITH INTEGRAL SHROUD
Abstract
An integrally bladed rotor for use in a gas turbine engine
includes a central hub; a plurality of airfoils extending from the
central hub, each airfoil with a tip, a leading edge and a trailing
edge; and a shroud with a metallic portion connecting to the tip of
each airfoil to rotate with the airfoils.
Inventors: |
Suciu; Gabriel L.;
(Glastonbury, CT) ; Chandler; Jesse M.; (South
Windsor, CT) ; Merry; Brian D.; (Andover,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Hartford |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
50931097 |
Appl. No.: |
13/716959 |
Filed: |
December 17, 2012 |
Current U.S.
Class: |
416/189 |
Current CPC
Class: |
F05D 2300/133 20130101;
F05D 2300/174 20130101; F05D 2300/603 20130101; F05D 2220/36
20130101; F04D 29/023 20130101; F01D 5/34 20130101; F05D 2260/96
20130101; F05D 2300/173 20130101; Y02T 50/672 20130101; F05D
2300/614 20130101; F01D 21/045 20130101; F01D 5/225 20130101; Y02T
50/60 20130101; F04D 29/321 20130101; F05D 2230/53 20130101; F05D
2300/121 20130101 |
Class at
Publication: |
416/189 |
International
Class: |
F01D 5/22 20060101
F01D005/22 |
Claims
1. An integrally bladed rotor for use in a gas turbine engine
comprising: a central hub; a plurality of airfoils extending from
the central hub, each airfoil with a tip, a leading edge and a
trailing edge; and a shroud with a metallic portion connecting to
the tip of each airfoil to rotate with the airfoils.
2. The integrally bladed rotor of claim 1, wherein the shroud is
integral to the airfoils.
3. The integrally bladed rotor of claim 1, wherein the shroud is
the same material as the airfoils.
4. The integrally bladed rotor of claim 1, wherein the entire
shroud is metallic.
5. The integrally bladed rotor of claim 1, wherein the shroud
comprises: a metallic portion; and a composite portion.
6. The integrally bladed rotor of claim 5, wherein the metallic
portion comprises: a metallic portion curved in the circumferential
direction extending from the leading edge to the trailing edge of
each airfoil; a first radial outward flange extending from the
metallic portion at the leading edge; and a second radial outward
flange extending from the metallic portion at the trailing
edge.
7. The integrally bladed rotor of claim 6, wherein the composite
portion wraps around the metallic portion between the first radial
outward flange and the second radial outward flange.
8. The integrally bladed rotor of claim 1, and further comprising:
a fan casing surrounding the integrally bladed rotor.
9. The integrally bladed rotor of claim 8, wherein the fan casing
is spaced apart from the shroud with a tight clearance.
10. The integrally bladed rotor of claim 1, wherein the integrally
bladed rotor is metallic.
11. The integrally bladed rotor of claim 1, wherein the integrally
bladed rotor is composite.
12. A fan comprising: an integrally bladed rotor with a plurality
of blades with tips; a shroud extending around the blades and
securing to the tips of each blade; and a fan casing surrounding
the shroud, wherein the shroud is at least partially metallic.
13. The fan of claim 12, wherein the integrally bladed rotor and
the shroud are entirely metallic.
14. The fan of claim 12, wherein the integrally bladed rotor and
the shroud are the same material.
15. The fan of claim 12, wherein the integrally bladed rotor and
the shroud are formed integrally.
16. The fan of claim 12, wherein the shroud comprises: a metallic
portion; and a composite portion.
17. The fan of claim 16, wherein the metallic portion comprises: a
ring having an inner surface connected to the tips of the blades
and an outer surface that includes a circumferential channel.
18. The fan of claim 17, wherein the composite portion wraps around
the metallic portion in the circumferential channel.
19. The fan of claim 12, wherein the fan casing is spaced apart
from the shroud with a tight clearance.
Description
BACKGROUND
[0001] Fans blades in gas turbine engines are sensitive to blade
vibrations or flutter. This is especially pronounced when fans have
a lower pressure ratio, for example when an engine is connected
directly to an aircraft body (instead of under a wing). The
connection directly to the aircraft body leads to more turbulent
air entering the fan. A method of minimizing flutter in this
scenario is to use a variable area fan nozzle ("VAFN") to change
the area at the back end of the fan. The VAFN can create or
eliminate back pressure to get the fan out of the flutter
range.
SUMMARY
[0002] An integrally bladed rotor for use in a gas turbine engine
includes a central hub; a plurality of airfoils extending from the
central hub, each airfoil with a tip, a leading edge and a trailing
edge; and a shroud with a metallic portion connecting to the tip of
each airfoil to rotate with the airfoils.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1A is a front view of a fan with an integral shroud in
a fan casing.
[0004] FIG. 1B is a perspective view of the fan with integral
shroud of FIG. 1A with the fan casing partially cut away.
[0005] FIG. 2A is a perspective view of a second embodiment of a
fan with a shroud.
[0006] FIG. 2B is a cross-sectional view of the shroud of FIG.
2A.
DETAILED DESCRIPTION
[0007] FIG. 1A is a front view of fan 10 with an integral shroud 12
in fan casing 14. FIG. 1B is a perspective view of fan 10 with
integral shroud 12 with fan casing 14 partially cut away. A partial
portion of an aircraft body 16 is also shown. Fan 10 is an
integrally bladed rotor type fan, with hub 18 and a plurality of
airfoils 20 extending radially from hub 18. Each airfoil 20
includes tip 22, leading edge 24 and trailing edge (not shown).
[0008] In the embodiment shown, hub 18, airfoils 20 and shroud 12
are formed as an integral unit. They can be formed, for example, of
a metallic material, for example, aluminum or titanium (including
alloys) and machined into shape desired. In alternate embodiments,
shroud 12 can be formed separately and connected to integrally
bladed rotor fan 10.
[0009] Shroud 12 connects to tips 22 of airfoils 20, extending from
leading edge 24 to trailing edge, and rotates with airfoils 20.
Shroud 12 is spaced apart from case 14 with a tight clearance, for
example, 0 mm (0 inches) to 2.54 mm (0.100 inches). Fan 10 acts to
pull air into engine as airfoils 20 and shroud 12 spin in case
14.
[0010] As can be seen in FIGS. 1A-1B, integrally bladed rotor fan
10 is mounted to aircraft body 16. At this position, the boundary
layer of air coming into the fan can have distortions, which can
lead to vibrations or flutter in airfoils 20. As too much flutter
in airfoils 20 could result in damage and/or a catastrophic failure
of the airfoil 20, the minimization of flutter is desirable.
[0011] Shroud 12 connects to tips 22 of airfoils 20 to stabilize
airfoils by providing a second connection to airfoils 20; the first
connection being to hub 18 at the inner diameter and the second
connection to shroud 12, at outer diameter. These stabilizing
connections reduce the airfoil vibratory effects of fan 10, even
when receiving a turbulent airflow. In past systems, blade flutter
due to this turbulent airflow was controlled by using a variable
area fan nozzle ("VAFN") downstream from the fan. The VAFN was able
to reduce flow through the fan by controlling the area at the back
end of the fan, and thus increasing or decreasing back pressure.
Although this was an effective way of reducing blade flutter, the
VAFN is a large and heavy system which reduced efficiency of the
overall engine.
[0012] Fan 10 with integral shroud 12 controls vibration and
flutter in airfoils 20 without the need for a VAFN, reducing size
and weight as compared to past systems. By forming shroud 12
integral to the fan 10, shroud 12 can also help to eliminate some
stresses in airfoils 20 as it can carry some of blade load when fan
10 is in operation. Integrally formed shroud 12 will also eliminate
blade tip 22 leakage in fan 10 (which can lead to loss of
efficiency and potential stalls), and the tight clearance between
shroud 12 and casing 14 will minimize performance losses caused by
air going outside of the shroud 12.
[0013] FIG. 2A is a perspective view of a second embodiment of fan
10 with hybrid shroud 32, with part of fan casing 14 cut away, and
FIG. 2B is a cross-sectional view of shroud 32. A partial portion
of an aircraft body 16 is also shown. Fan 10 is an integrally
bladed rotor type fan, with hub 18 and a plurality of airfoils 20
extending radially from hub 18. Each airfoil 20 has tip 22, leading
edge 24 and trailing edge 25. Shroud 32 includes metallic portion
34 (with circumferentially curved portion 36, first ridge 38 and
second ridge 40) and composite portion 42.
[0014] Shroud 32 metallic portion 34 connects to tips 22 of
airfoils 20, and can be formed integral to fan 10 or can be formed
separate and attached to tips 22. Circumferentially curved portion
36 of shroud connects to tips 22 and extends from leading edge 24
to trailing edge 25 of airfoils 20. First flange 38 extends
perpendicular from circumferentially curved portion 36 outward,
away from airfoils 20 at leading edge 24. Second flange 40 extends
perpendicular from circumferentially curved portion 36 outward,
away from airfoils 20 at trailing edge 25. Composite portion 42 can
be a composite wrap that wraps circumferentially around
circumferentially curved portion 36 between first flange 38 and
second flange 40.
[0015] As in FIGS. 1A-1B, shroud 32 spins with fan 10 as fan pulls
air into engine within case 14. Hybrid shroud 32 with metallic
portion 34 and composite portion 42 allows for a high-strength,
light-weight shroud 32 that can help stabilize airfoils 20 at outer
diameter (tip 22) to reduce blade vibrations and flutter even when
fan 10 is ingesting a very turbulent airflow. Metallic portion 34
of shroud 32 can be formed integral to fan 10 airfoils 20, ensuring
high strength in connection at tips 22, and composite portion 42
can be wrapped around to reinforce metallic portion 34 without
adding a lot of additional weight. Shroud 32 can also increase hoop
strength of fan 10.
[0016] In summary, fan 10 with integral shroud 12, 32 reduces or
eliminates vibrations or flutter in blades, eliminating the need
for heavy and large VAFNs used in past systems to reduce flutter.
Integral shroud 12, 32 connects to airfoil tips 22 to stabilize
blade at outer diameter, thereby allowing fan 10 airfoils 20 to
resist vibrations even when ingesting very turbulent airflows.
[0017] An integrally bladed rotor for use in a gas turbine engine
includes a central hub; a plurality of airfoils extending from the
central hub, each airfoil with a tip, a leading edge and a trailing
edge; and a shroud with a metallic portion connecting to the tip of
each airfoil to rotate with the airfoils.
[0018] Additional and/or alternative embodiments include the shroud
being integral to the airfoils; the shroud being the same material
as the airfoils; the entire shroud being metallic; the shroud
comprising a metallic portion and a composite portion; the metallic
portion comprising a metallic portion curved in the circumferential
direction extending from the leading edge to the trailing edge of
each airfoil, a first radial outward flange extending from the
metallic portion at the leading edge, and a second radial outward
flange extending from the metallic portion at the trailing edge;
the composite portion wrapping around the metallic portion between
the first radial outward flange and the second radial outward
flange; a fan casing surrounding the integrally bladed rotor; the
fan casing being spaced apart from the shroud with a tight
clearance; the integrally bladed rotor being metallic; and/or the
integrally bladed rotor being composite.
[0019] A fan includes an integrally bladed rotor with a plurality
of blades with tips; a shroud extending around the blades and
securing to the tips of each blade; and a fan casing surrounding
the shroud, wherein the shroud is at least partially metallic.
[0020] Additional and/or alternative embodiments include the
integrally bladed rotor and the shroud being entirely metallic; the
integrally bladed rotor and the shroud being the same material; the
integrally bladed rotor and the shroud being formed integrally; the
shroud comprising a metallic portion and a composite portion; the
metallic portion comprising a ring having an inner surface
connected to the tips of the blades and an outer surface that
includes a circumferential channel; the composite portion wrapping
around the metallic portion in the circumferential channel; and/or
the fan casing being spaced apart from the shroud with a tight
clearance.
[0021] While the invention has been described with reference to an
exemplary embodiment(s), 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 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(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
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