U.S. patent application number 11/024732 was filed with the patent office on 2007-02-22 for monobloc flameholder arm for an afterburner device of a bypass turbojet.
This patent application is currently assigned to SNECMA MOTEURS. Invention is credited to Stephane Blanchard, Pierre Camy, Eric Conete, Georges Habarou, Thierry Pancou, Stephane Touchaud.
Application Number | 20070039327 11/024732 |
Document ID | / |
Family ID | 34630667 |
Filed Date | 2007-02-22 |
United States Patent
Application |
20070039327 |
Kind Code |
A1 |
Blanchard; Stephane ; et
al. |
February 22, 2007 |
MONOBLOC FLAMEHOLDER ARM FOR AN AFTERBURNER DEVICE OF A BYPASS
TURBOJET
Abstract
A support arm (13) is intended to be installed in a radial
position in an afterburner device of a bypass turbojet. The device
comprises first and second inner annular casings defining a passage
for a primary flow and an outer annular casing defining together
with the first inner annular casing a passage for a secondary flow.
The arm (13) comprises a monobloc structure made of composite
material including two integral walls (14, 15), on the one hand,
designed to define a groove (16) having a substantially V-shaped
profile and, on the other hand, including first end parts (17)
joined together and adapted to define a foot (18) and second end
parts (19) adapted each to define at least one flange (20, 21)
intended to be positively connected to the outer annular
casing.
Inventors: |
Blanchard; Stephane;
(Chartrettes, FR) ; Touchaud; Stephane; (Paris,
FR) ; Pancou; Thierry; (Saintry Sur Seine, FR)
; Conete; Eric; (Merignac, FR) ; Camy; Pierre;
(Saint Medard En Jalles, FR) ; Habarou; Georges;
(Le Bouscat, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA MOTEURS
PARIS
FR
|
Family ID: |
34630667 |
Appl. No.: |
11/024732 |
Filed: |
December 30, 2004 |
Current U.S.
Class: |
60/765 ;
60/796 |
Current CPC
Class: |
F23R 3/18 20130101; F02K
3/10 20130101 |
Class at
Publication: |
060/765 ;
060/796 |
International
Class: |
F02K 3/10 20060101
F02K003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2004 |
FR |
04 00651 |
Claims
1. A support arm for an afterburner device of a bypass turbojet,
said device comprising first and second inner annular casings
defining a passage for a primary flow and an outer annular casing
defining together with he said first inner annular casing a passage
for a secondary flow, said support arm comprising: a monobloc
structure made of composite material including two integral walls
designed to define a groove having a substantially V-shaped profile
and including first end parts joined together and adapted to define
a foot and second end parts adapted each to define at least one
flange which can be positively connected to the said outer casing,
wherein the thickness of said walls is not constant between said
first and second end parts.
2. The arm according to claim 1, wherein the spacing of said walls
is not constant between said first and second end parts, such that
the profile of said groove varies.
3. The arm according to claim 2, wherein said spacing varies
substantially continuously, increasing from the first end parts to
the second end parts, such that the profile of said groove varies
substantially continuously.
4. (canceled)
5. The arm according to claim 4, characterised wherein the
thickness of the said walls is greater at the said second end
parts.
6. The arm according to claim 1, wherein said walls each include a
notch at the same selected level so as to define a housing which
can receive a burner ring support.
7. The arm according to claim 6, wherein said burner ring support
is positively connected to the said walls, in the vicinity of the
said notches.
8. The arm according to claim 6, wherein said burner ring support
is positively connected to said walls with rivets.
9. The arm according to claim 6, wherein said notches are formed in
a zone of a part of said walls intended to be placed in the passage
for the secondary flow.
10. The arm according to claim 9, wherein said zone is intended to
be placed in the vicinity of said first inner casing
11. The arm according to claim 1, wherein each flange can be
positively connected to said outer casing with at least one bolt,
with the interposition of a backing plate on the side of the flange
exposed to said secondary flow.
12. The arm according to claim 1, wherein said monobloc structure
is made of a composite material having a ceramic matrix.
13. An afterburner device for a bypass turbojet, comprising: first
and second inner annular casings defining a passage for a primary
flow and an outer annular casing defining together with said first
inner annular casing a passage for a secondary flow, at least three
support arms, each according to claim 1 positively connected to
said outer annular casing.
14. The device according to claim 13, further comprising, in the
passage for said secondary flow, an insulating liner defining
together with said outer annular casing an afterburner jet pipe for
part of said secondary flow, and wherein said burner support ring
of each support arm is placed at a level between the level of said
insulating liner and the level of said first inner annular
casing.
15. A turbojet comprising a support arm according to claim 1.
16. A turbojet comprising a support arm according to claim 2.
17. A turbojet comprising a support arm according to claim 3.
18. A turbojet comprising a support arm according to claim 5.
19. A turbojet comprising a support arm according to claim 6.
20. A turbojet comprising a support arm according to claim 7.
Description
[0001] The invention relates to the field of bypass turbojets and,
more particularly, the afterburner devices provided in turbojet
engines of this kind.
[0002] In a bypass turbojet of the type shown in FIG. 1, the air
flow drawn in by a fan 1 supplies a low-pressure compressor 2. A
first part of the compressed-air flow supplies a high-pressure
compressor 3, while a second (complementary) part is intended to
supply a first passage 4 further downstream defined between an
outer annular casing 5 and a first inner annular casing 6 (usually
referred to as a flow separator and serving to separate the primary
flow from the secondary flow before they are mixed together) of an
afterburner device 7. The compressed-air flow through the
high-pressure compressor 3 supplies a combustion chamber 8 which
supplies exhaust gas to a turbine 9 comprising a high-pressure
stage followed by a low-pressure stage and the outlet of which
supplies a second passage 10 defined between the first inner
annular casing 6 (or flow separator) and a second inner annular
casing 11 (usually referred to as an exhaust cone) of the
afterburner device 7.
[0003] The exhaust gases supplying the second passage 10 are at an
elevated temperature and form what is usually referred to as a
primary flow (or hot flow). The air supplying the first passage 4
is at a substantially lower temperature than that of the primary
flow and forms what is usually referred to as a secondary flow (or
bypass flow).
[0004] The afterburner device 7 allows a second combustion
operation to be carried out by virtue of the injection of fuel into
the primary and secondary flows. Part of this injection operation
is effected with the aid of a burner ring 12 placed in the vicinity
of the first inner casing 6 (or flow separator) in the passage for
the secondary flow or for the primary flow. More precisely, the
burner ring 12 allows part of the fuel to be injected in a
homogeneous manner and the flame to be stabilised.
[0005] According to the embodiment selected, the burner ring 12 is
carried by support arms 13, also referred to as "flameholder arms",
positively connected to the outer casing by means of a support
element and/or to the first inner casing by means of fixing
means.
[0006] The positive connection of the arms to the outer casing by
means of a support element is described, in particular, in the
document FR 2 699 226. As the support element and the associated
arm are positively connected together in a region traversed by the
primary flow, the components ensuring this positive connection are
therefore subjected not only to considerable thermal stresses, but
also to stresses referred to as "airflow pressure". Each arm
moreover forms together with a burner ring portion a monobloc
sub-structure which is particularly difficult to produce as a
result, in particular, of the presence of several rounded
edges.
[0007] The positive connection of the arms to the first inner
casing by means of fixing means is described, in particular, in the
documents U.S. Pat. No. 5,103,638, GB 2 295 214, U.S. Pat. No.
5,022,805 and U.S. Pat. No. 5,090,198. In each of these documents,
the arms made of composite material are supposed to be positively
connected to a metal inner casing placed at the interface between
the primary and secondary flows. This results in a difference in
thermal expansion between the arms and the casing, compensated for
by the use of complex fixing means and interface components.
[0008] It is also proposed in the document FR 2 699 227 to form a
monobloc structure consisting of the outer and inner casings, the
burner ring and the arms. However, a structure of this kind is
difficult to produce, particularly as a result of the fact that
different materials have to be used for the "cold" components and
the "hot" components. Maintenance operations are moreover difficult
as a result of the monobloc nature of this structure and damage to
one of its components will necessitate the complete replacement
thereof.
[0009] The aim of the invention is therefore to improve the
situation.
[0010] To this end, it proposes a support (flameholder) aim for an
afterburner device comprising, as indicated in the introductory
part, first and second inner annular casings defining a passage for
the primary flow and an outer annular casing defining together with
the first inner annular casing a passage for the secondary
flow.
[0011] This arm is characterised in that it comprises a monobloc
structure made of composite material including two integral walls,
on the one hand, designed to define a groove having a substantially
V-shaped profile and, on the other hand, including first end parts
joined together and adapted to define a foot and second end parts
adapted each to define at least one flange intended to be
positively connected to the outer casing.
[0012] The arm according to the invention may include other
features which can be taken separately or in combination, in
particular: [0013] the spacing of its two walls may not be constant
between their first and second end parts, such that the profile of
the groove can vary. In this case, the spacing varies, e.g.
substantially continuously, increasing from the first end parts to
the second end parts, such that the profile of the groove can vary
substantially continuously; [0014] the thickness of its two walls
may not be constant between their first and second end parts. In
this case, e.g. the thickness of the two walls is greater at their
second end parts in order to increase their resistance; [0015] its
two walls may each include a notch at the same selected level so as
to define a housing which can receive a burner ring support. E.g.
this burner ring support is positively connected to the two walls
in the vicinity of their notches, possibly with the aid of rivets.
The notches may moreover be formed in a zone of a part of the two
walls intended to be placed in the passage for the secondary flow.
This zone is then preferably placed in the vicinity of the first
inner casing; [0016] each flange can be positively connected to the
outer casing by means of at least one bolt, with the interposition
of a backing plate on the side exposed to the secondary flow;
[0017] the monobloc structure can be made of a composite material
having a ceramic matrix.
[0018] The invention also relates to an afterburner device of the
aforementioned type for a bypass turbojet, comprising at least
three support arms of the type described hereinbefore according to
one of the preceding features, positively connected to its outer
casing.
[0019] A device of this kind may comprise, e.g. in its passage for
the secondary flow an insulating liner defining together with the
outer casing an afterburner jet pipe for part of the secondary
flow. In this case, the burner ring support of each support arm is
preferably installed at a level between the respective levels of
the insulating liner and the first inner casing.
[0020] Other features and advantages of the invention will be clear
from the detailed description hereinafter and from the accompanying
drawings, in which:
[0021] FIG. 1 is a diagrammatic longitudinal section of a bypass
turbojet;
[0022] FIG. 2A is a first perspective view of an embodiment of an
arm according to the invention, before the fixing of a burner ring
support;
[0023] FIG. 2B is a second perspective view of the arm of FIG.
2A;
[0024] FIG. 3 is a perspective view of an embodiment of an arm
according to the invention, after the fixing of a burner ring
support;
[0025] FIG. 4 is a top view of the arm of FIG. 3;
[0026] FIG. 5 is a sectional view along the axis V-V of the arm of
FIG. 3;
[0027] FIG. 6 is a sectional view along the axis VI-VI of the arm
of FIG. 3;
[0028] FIG. 7 is a side view of the arm of FIG. 3, after the
positive connection to the outer casing of the afterburner device,
and
[0029] FIGS. 8A and 8B are two perspective views showing the
assembly of FIG. 7 from two different angles.
[0030] The accompanying drawings may serve not only to complete the
invention, but also to help to define it, where appropriate.
[0031] The invention relates to a support flameholder arm for an
afterburner device of a turbojet engine of the type described in
the introductory part with reference to FIG. 1.
[0032] A support arm 13 according to invention will now be
described with reference firstly to FIGS. 1, 2A and 2B.
[0033] The support arm (or flameholder arm) 13 shown in FIGS. 2A
and 2B is in the form of a monobloc structure made of a
heat-resistant composite material. This composite material
preferably has a ceramic matrix. E.g. the monobloc structure is
made from a fibre preform, in particular of silicon carbide or
carbon, into which a ceramic matrix in the liquid or gaseous phase
is infiltrated. The monobloc structure can thus be made, e.g. with
CERASEP.RTM. 410-12.
[0034] The use of a composite material is particularly advantageous
as a result of the fact that it allows for a weight gain (compared
to metal materials) and an increase in service life, particularly
in the event of elevated operating temperatures.
[0035] The monobloc structure includes two substantially
symmetrical walls 14 and 15 joined together on one longitudinal
side so as to define a groove 16, the profile of which is
substantially V-shaped in cross section.
[0036] These two walls 14 and 15 include first end parts 17 joined
together and adapted to define a preferably bevelled foot 18 so as
to promote the primary flow.
[0037] Each wall 14 and 15 moreover also includes a second end part
19 opposite the foot 18 and adapted to define at least one flange
20, 21 intended to be positively connected to the outer annular
casing 5, as will be seen hereinafter with reference to FIG. 7. In
order to allow for this positive connection, e.g. with the aid of
bolts, each flange 20, 21 includes at least one through orifice 22,
and preferably at least two, as shown in FIG. 2B.
[0038] In addition, each wall 14, 15 preferably includes a notch
(or slot) 23 at a selected level (identical for both). These two
notches 23 define a housing in which a burner ring support 24 can
be placed, as shown in FIG. 3.
[0039] The level at which the notches 23 are formed is selected as
a function of the intended location of the burner ring. In the
example shown, they are provided in the vicinity of the second ends
19 so that the burner ring is placed in the duct 4 for the
secondary flow. However, in a variant, they could be placed in a
central part of the walls 14 and 15, or even in the vicinity of the
foot 18 so that the burner ring is placed in the duct 10 for the
primary flow.
[0040] E.g., as shown in FIG. 3, the burner ring support 24
includes a central part 25 defining a V-shaped groove open on two
sides and extended substantially perpendicularly towards the rear
by two lateral parts 26 positively connected to inner faces of the
two walls 14 and 15 in the vicinity of their notches 23. This
positive connection can be effected, e.g. with the aid of rivets
27.
[0041] The burner ring support 24 is made, e.g. of a metal material
when it is situated in the "cold" secondary zone. However, it can
also be made of a composite material, particularly when it is
installed in the "hot" primary zone.
[0042] So as to allow for the positive connection of the burner
ring to the burner ring support 24, the latter preferably includes
at least one through orifice 28 on each of the two wings forming
its central part 25.
[0043] As shown by the sectional views along the axes V-V and VI-VI
of FIG. 3 shown in FIGS. 5 and 6 and by the top view shown in FIG.
4, the spacing between the two walls 14 and 15 may not be constant
from the foot 18 to the second end parts 19. In other words, the
V-shaped profile of the groove 16 can vary. More precisely, the
spacing in this case increases substantially continuously from the
foot 18 to the second end parts 19.
[0044] Although not shown in the figures, the thickness of the two
walls 14 and 15 may moreover not be constant from the foot 18 to
the second end parts 19, as it may be advantageous for part of the
support arm 13 subjected to higher stresses than the other parts to
be reinforced. Excessive thickness at the second end parts 19
therefore means that they will be more resistant to thermal
stresses and to stresses due to airflow pressure.
[0045] An afterburner device 7 of a bypass turbojet includes at
least three support arms 13 of the type described hereinbefore, and
more preferably at least four. In some turbojet engines, the number
of arms may be equal to nine (9).
[0046] An example of the positive connection of a support arm 13 to
the outer annular casing 5 of an afterburner device 7 will now be
described with reference to FIGS. 7, 8A and 8B.
[0047] As described hereinbefore, each support arm 13 is positively
connected by means of its flanges 20, 21 to the outer annular
casing 5.
[0048] As the positive connection is effected directly to the outer
annular casing 5 in a "cold" environment (typically less than
approximately 200.degree. C.), there is no problem with a
difference in thermal expansion between the support arm 13 and the
outer annular casing 5. It is therefore possible to use
particularly simple fixing (or positive connection) means, e.g.
bolts 29. It is possible to use, e.g. two bolts 29 (and a minimum
of one) in order to fix each flange 20, 21 in position.
[0049] Once positively connected, each arm extends substantially in
a radial direction in relation to the axis of rotation of the
turbine 9, also forming the axis of revolution of the outer 5 and
inner 6 and 11 casings. It will be recalled that the expressions
"inner casing 6" and "inner casing 11" as used here refer to what
the person skilled in the art refers to respectively as the flow
separator and the exhaust cone.
[0050] As shown in FIG. 7, the afterburner device 7 may include an
insulating liner 32 interposed between the first inner annular
casing 6 (or flow separator) and the outer annular casing 5 and
defining together with the latter an afterburner jet pipe 33 in
which at least part of the secondary flow circulates. This
insulating liner 32 is generally a corrugated, multi-perforated
plate intended to contain the afterburning gases (just like the
walls of a principal chamber) and to protect the outer annular
casing 5 from the hot flow. If an insulating liner 32 of this kind
is present, the notches 23 in the walls 14 and 15 of each support
arm 13 are formed at a level selected in such a manner that the
burner ring support 24 is at least partially surrounded by the
intermediate annular casing 32 and the first inner annular casing 6
(or flow separator).
[0051] As shown more clearly in FIG. 3, a reinforcing and/or
protective backing plate 30 can moreover be placed under the outer
face (opposite the outer casing 5) of each flange 20, 21 so that it
is interposed between the latter and the nut or nuts. This makes it
possible to increase the rigidity of the flanges 20 and 21 and to
increase the resistance of the support arm 13 to mechanical
stresses. This backing plate 30 is preferably made of metal.
[0052] It should be noted that the V-shaped profile and the shape
of the foot 18 of each support arm 13 are selected so as to
optimise the primary flow (arrow F1 in FIG. 7) and the secondary
flow (arrow F2 in FIG. 7) and therefore to obtain aerodynamic
behaviour corresponding to the expected performance.
[0053] A support arm 13 may moreover house an inner carburation
device in its groove 16. As a result of the composite material used
to produce the support arm 13, the latter can moreover withstand
elevated temperatures, so that it is not necessary to provide it
with an inner ventilation device intended to cool the component
from its leading edge traversed by the primary flow.
[0054] The invention is not limited to the embodiments of the
support arm and afterburner device described hereinbefore merely by
way of example, but covers any variants which may be envisaged by
the person skilled in the art within the scope of the claims
hereinafter.
* * * * *