U.S. patent application number 12/165995 was filed with the patent office on 2009-01-22 for chamber-bottom baffle, combustion chamber comprising same and gas turbine engine fitted therewith.
This patent application is currently assigned to SNECMA. Invention is credited to Patrice Andre Commaret, Didier Hippolyte Hernandez, Romain Nicolas Lunel.
Application Number | 20090019856 12/165995 |
Document ID | / |
Family ID | 39267949 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090019856 |
Kind Code |
A1 |
Commaret; Patrice Andre ; et
al. |
January 22, 2009 |
CHAMBER-BOTTOM BAFFLE, COMBUSTION CHAMBER COMPRISING SAME AND GAS
TURBINE ENGINE FITTED THEREWITH
Abstract
The present invention relates to a baffle (10) for the bottom of
a combustion chamber of a gas turbine engine, comprising a flat
portion of wall (10a) with an opening for an injector of the
combustion chamber to pass through, two longitudinal edges (10c,
10d) for the assembly to two adjacent baffles and two transverse
edges (10e, 10f), wherein at least one of the edges comprises a
joint cover (10d1) arranging a housing (10d10) along said edge for
an edge (10'c) of an adjacent baffle (10') so as to seal the
junction between the two edges. The invention also relates to a
combustion chamber incorporating said baffles.
Inventors: |
Commaret; Patrice Andre;
(Rubelles, FR) ; Hernandez; Didier Hippolyte;
(Quiers, FR) ; Lunel; Romain Nicolas; (Montereau
Sur Le Jard, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA
Paris
FR
|
Family ID: |
39267949 |
Appl. No.: |
12/165995 |
Filed: |
July 1, 2008 |
Current U.S.
Class: |
60/752 ;
60/722 |
Current CPC
Class: |
F23R 3/04 20130101; F23R
3/10 20130101; F23R 3/50 20130101; F23R 3/002 20130101 |
Class at
Publication: |
60/752 ;
60/722 |
International
Class: |
F23R 3/42 20060101
F23R003/42 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2007 |
FR |
0704869 |
Claims
1. A baffle for the bottom of a combustion chamber of a gas turbine
engine, comprising a portion of wall with an opening for an
injector of the combustion chamber to pass through, two
longitudinal edges and two transverse edges, wherein at least one
of the longitudinal edges comprises a joint cover arranging a
housing along said edge for a fitted tongue or the edge of an
adjacent baffle so as to seal the junction between the two edges
while allowing them to slide relative to one another when the wall
of the chamber bottom expands.
2. The baffle as claimed in claim 1, wherein the housing is formed
by a crank of the wall.
3. The baffle as claimed in claim 1, wherein the housing is formed
by a groove.
4. The baffle as claimed in one of the preceding claims, wherein
the transverse edges comprise a curved portion of wall, the
housings being arranged equally along the longitudinal edges of
said curved portion.
5. The deflector comprising a joint cover as claimed in one of the
preceding claims along a longitudinal edge and an edge without a
joint cover along the other longitudinal edge, the two edges being
matched in order to adapt to an edge of another same baffle placed
edge-to-edge.
6. The baffle comprising a joint cover along the two longitudinal
edges as claimed in one of claims 1 to 4.
7. The baffle comprising two longitudinal edges matching the joint
covers of the baffle of claim 6.
8. A combustion chamber of a gas turbine engine, being annular
comprising an outer wall, an inner wall, a wall connecting the two
walls and forming a chamber bottom, baffles as claimed in at least
one of the preceding claims and comprising a portion of wall
parallel to the chamber bottom, being fitted in the bottom.
9. The combustion chamber as claimed in the preceding claim, with
baffles as claimed in claim 5, all being identical.
10. The combustion chamber as claimed in claim 8 with baffles as
claimed in claim 3, all the baffles being identical, a metal tongue
being housed in the grooves of the joint covers.
11. The combustion chamber as claimed in claim 8 with baffles as
claimed in claims 6 and 7 taken together, wherein the baffles as
claimed in claim 6 alternate with the baffles of claim 7.
12. The combustion chamber as claimed in one of claims 8 to 11,
wherein the chamber bottom comprises a channel arranging an air gap
between the chamber bottom and the joint covers.
13. A chamber of the convergent type as claimed in one of claims 8
to 12.
14. A gas turbine engine comprising a combustion chamber as claimed
in any one of claims 8 to 14.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to the technical field of
combustion chambers for gas turbine engines. Its particular subject
is the chamber bottom. Its final subject is a gas turbine engine
such as a turbojet fitted with such a combustion chamber.
[0002] In all of the following, the terms "axial", "radial",
"transverse" correspond respectively to an axial direction, to a
radial direction, and to a transverse plane of the engine, the
terms "upstream" and "downstream" correspond respectively to the
direction of flow of the gases in the engine.
[0003] A conventional divergent combustion chamber is illustrated
in FIG. 1, which is an axial section showing a half of the
combustion chamber, the other half of the latter being deduced by
symmetry relative to the axis of the engine (not shown). The
combustion chamber 110 is housed in a diffusion chamber 130 that is
an annular space defined between an outer casing 132 and an inner
casing 134, in which a compressed comburant, ambient air,
originating upstream of a compressor (not shown) is inserted via an
annular diffusion duct 136.
[0004] This divergent combustion chamber 110 comprises two
concentric walls, one outer 112 and the other inner 114, that are
coaxial and substantially conical. The walls flare out from
upstream to downstream. The outer wall 112 and inner wall 114 of
the combustion chamber 110 are connected together, toward the
upstream of the combustion chamber, by a chamber bottom 116.
[0005] The chamber bottom 116 is a frustoconical annular part which
extends between two substantially transverse planes while flaring
out from downstream to upstream. The chamber bottom 116 is
connected to each of the two walls, outer 112 and inner 114, of the
combustion chamber 110. The chamber bottom 116 is slightly conical.
It is furnished with injection systems 118 through which injectors
120 pass that insert the fuel at the upstream end of the combustion
chamber 110 where the combustion reactions take place.
[0006] These combustion reactions have the effect of causing heat
to radiate from downstream to upstream in the direction of the
chamber bottom 116. Therefore in operation the chamber bottom is
subjected to high temperatures. In order to protect it, sectorized
heat screens, also called baffles 122, are placed between the
center and the walls of the chamber bottom. These baffles 122, one
of which is represented in FIG. 3, are substantially flat plates
attached by brazing to the chamber bottom 116 with a central
opening 122a for the injection system to pass through. They
comprise two low lateral walls 122b 122c along the radial edges,
turned toward the wall of the chamber bottom and two air guidance
tongues 122e 122f along the transverse edges turned toward the
center and arranging a space with the inner, respectively outer,
walls 114 and 112 of the chamber. The baffles are cooled by the
impacts of cooling air jets entering the combustion chamber 110
through cooling orifices 124 pierced in the chamber bottom 116. The
air forming these jets, flowing from upstream to downstream, is
guided by chamber fairings 126, passes through the chamber bottom
116 through the cooling orifices and comes to impact the upstream
face of the baffles 122. The air is then guided radially toward the
inside and outside of the center in order to initiate the film for
cooling the walls 114 and 112 respectively.
[0007] This guidance along the baffles is ensured by the
radially-oriented lateral low walls. These low walls also have a
sealing function. Being in contact with or providing a minimal
clearance with the chamber bottom, they prevent the air from mixing
between two adjacent baffles, entering the center and disrupting
the combustion. These disruptions have an impact on pollution and
are to be avoided. Specifically, the performance in discharge of
pollutants, CO and CHx, are capable of being harmed by the
undesirable insertion of this cold air particularly when the engine
is idling when the clearance is greatest.
DESCRIPTION OF THE PRIOR ART
[0008] In the context of other engine architectures in which the
gas flow is generally convergent between the outlet of the
compressor and the inlet of the turbine, there are combustion
chambers that are called convergent; the outer and inner walls of
the combustion chamber are inclined while flaring out from
downstream to upstream, and not from upstream to downstream as with
the first combustion chambers mentioned above, called divergent.
These convergent combustion chambers may have a larger cone angle
than the cone angle of the divergent combustion chambers.
[0009] Such a great inclination of the combustion chamber has
repercussions on the conicity of the chamber bottom and on the
position of the baffles relative to the chamber bottom. Such a
combustion chamber is partly illustrated in FIG. 2, in axial
section. This figure shows an axial direction 100 parallel to the
axis of the turbojet, the main direction 200 of the combustion
chamber 210, and the angle .alpha. between these two axes 100, 200.
Because of the great inclination of the combustion chamber 210, the
chamber bottom 216 has a conicity with a greater angle for a
convergent combustion chamber bottom. When not only the inclination
of the chamber bottom 216 is great, but also the injectors 220 are
present in reduced number and/or the combustion chamber 210 has a
small diameter, this affects the distance between the chamber
bottom and the flat baffles.
[0010] Therefore the geometry of the chamber bottom may also render
difficult the adjustments and tolerances necessary between the wall
of the chamber bottom and the baffles. The optimal operation of the
chamber is no longer ensured. The variation of the clearance
between the baffles on the one hand and the baffles and the chamber
bottom on the other hand is sufficiently great for the solution
using low lateral walls along the radial edges of the baffles to be
no longer satisfactory.
SUMMARY OF THE INVENTION
[0011] The object of the present invention is to remedy this
problem.
[0012] According to the invention, a baffle for the bottom of a
combustion chamber of a gas turbine engine is made comprising a
portion of wall with an opening for an injection system of the
combustion chamber to pass through, two longitudinal edges and two
transverse edges, wherein at least one of the longitudinal edges
comprises a joint cover arranging a housing along said edge for a
fitted tongue or the edge of an adjacent baffle so as to seal the
junction between said edge and the edge of an adjacent baffle.
[0013] The solution of the invention consists therefore in sealing
the space between the baffles so as not to be reliant on the
geometry of the combustion chamber and of the chamber bottom in
particular and to be able to absorb the dimensional variations
associated with the operation of the chamber between idling speed
and full throttle.
[0014] Various solutions are proposed: [0015] The housing is formed
by a crank of the wall. [0016] The housing is formed by a groove.
[0017] The transverse edges comprising a curved portion of wall,
the housings are arranged equally along the longitudinal edges of
said curved portion. [0018] The baffle comprises a joint cover
along a longitudinal edge and an edge without a joint cover along
the other longitudinal edge, the two edges being matched in order
to adapt to an edge of another same baffle placed edge-to-edge.
[0019] The baffle comprises a joint cover along the two
longitudinal edges. [0020] The baffle comprises two longitudinal
edges matching the joint covers.
[0021] The present invention also relates to a combustion chamber
of a gas turbine engine, that is annular comprising an outer wall,
an inner wall, a wall connecting the two walls and forming a
chamber bottom, and a plurality of baffles according to the
invention with a portion of wall parallel to the chamber bottom,
fitted in the bottom.
[0022] According to the embodiments: [0023] All the baffles are
identical or else [0024] the baffles with joint covers alternate
with the baffles without joint covers. [0025] The chamber bottom
comprises radial channels arranging air gaps between the chamber
bottom and the joint covers. [0026] The combustion chamber is of
the convergent type.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Other features and advantages will emerge from the following
description of embodiments of the invention with reference to the
appended drawings in which:
[0028] FIG. 1 represents in axial section a half of a combustion
chamber of the divergent type known per se;
[0029] FIG. 2 represents in axial section a half of a combustion
chamber of the convergent type known per se;
[0030] FIG. 3 shows a baffle of the prior art used for the thermal
protection of the wall of the combustion chamber bottom;
[0031] FIG. 4 shows, seen from the inside of the combustion
chamber, two adjacent baffles for the thermal protection of the
chamber bottom of the invention;
[0032] FIG. 5 shows the other face of the baffles of FIG. 4;
[0033] FIG. 6 shows the detail of the joint cover of the baffles of
FIGS. 4 and 5;
[0034] FIG. 7 shows a variant embodiment of the seal between two
adjacent baffles;
[0035] FIG. 8 shows the other face of the baffles of FIG. 7;
[0036] FIG. 9 shows the detail of the joint cover of the baffles of
FIGS. 7 and 8;
[0037] FIG. 10 is a view showing a radial channel arranged in the
wall of the chamber bottom to allow the achievement of an air gap
between the wall of the chamber bottom and the joint cover of the
baffles;
[0038] FIG. 11 shows, seen from above in the radial direction, the
air gap between the wall of the chamber bottom and the joint cover
at the connection between two adjacent baffles;
[0039] FIG. 12 shows another variant embodiment of the joint cover
seen from the inside of the combustion chamber;
[0040] FIG. 13 shows the edge of a baffle of FIG. 12 with a
tongue;
[0041] FIG. 14 shows the detail of the joint cover of FIGS. 12 and
13.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Reference is now made to FIGS. 4 to 6 representing a first
embodiment of the seal between two baffles 10 and 10' made of
refractory material placed side by side on the chamber bottom. The
baffle 10 comprises a flat portion 10a with a central opening 10b
corresponding to the housing of an injection system not shown. In
FIG. 5, the opening is bordered by a collar 10b1 with a shoulder
for attachment in the chamber bottom. The baffle comprises two
longitudinal edges that are oriented in a radial direction relative
to the axis of the engine, when it is in position. The longitudinal
edge 10c and the edge 10d are rectilinear. The baffle 10 also
comprises two transverse edges 10e and 10f both rounded to follow
the curvature of the combustion chamber and curved toward the
inside of the combustion chamber for the guidance of the air. The
edge 10c, on the left in FIG. 4, is rectilinear and follows the
radial profile of the baffle. The edge 10d of the other side
comprises a rear crank relative to the visible face in FIG. 4,
formed by a tongue 10d1 which extends the rear face of the baffle
wall. This crank forms a longitudinal housing 10d10 for the edge
10'c of the adjacent baffle 10'. This baffle 10' is identical to
the baffle 10. It comprises a flat portion 10'a, two longitudinal
edges 10'c and 10'd and two rounded and curved transverse edges
10'e and 10'f. The edge 10'd comprises a longitudinal tongue 10'd1
arranging a housing 10'd10.
[0043] In the example of FIGS. 4 to 6, the baffles are all
identical and are installed on the periphery of the chamber bottom
while being attached by the collars of the openings for the
injection systems. There is one injection system per baffle. The
joint cover formed by the tongue 10d1 of each of the baffles covers
the edge 10'c of the adjacent baffle 10' over a sufficient width to
accommodate the variations of expansion of the combustion chamber.
Each housing 10d10, 10'd10 is arranged to retain the edge 10c, 10'c
of the adjacent baffle so that the leaks between two adjacent
baffles are reduced if not totally eliminated irrespective of the
engine speed.
[0044] In the embodiment of FIGS. 4 to 6, the baffles are identical
but the solution also comprises the case in which a first baffle
comprises a joint cover along the two longitudinal edges
interacting with the simple edges of a second baffle without joint
cover. The effectiveness is the same. The installation is however
different and requires the manufacture of two part references.
[0045] FIGS. 7, 8 and 9 represent a first variant with a grooved
joint cover which improves the seal relative to the previous
solution.
[0046] This shows the baffles 20, 20' with a flat wall 20a, 20'a, a
central opening 20b, 20'b, two longitudinal edges 20c, 20'c and
20d, 20'd, and two rounded and curved transverse edges 20e, 20'e
and 20f, 20'f. The longitudinal edge 20d comprises a tongue 20d1
parallel to the wall of the baffle and arranging a groove-shaped
housing 20d10g. This groove is arranged so as to interact with the
edge 20'c of the adjacent baffle. Here the edge 20'c forms a rear
crank to engage in the groove 20d10g. The clearance is sufficient
to allow the expansion of the combustion chamber during the various
engine speeds while retaining a sealed contact between the edge
20'c and the sides of the groove 20d10g.
[0047] As in the previous solution, the baffles may be all
identical or may alternate: one with joint covers on the two edges
and the other with simple edges interacting with the grooves of the
edges with joint covers.
[0048] FIGS. 10 and 11 show an enhancement between the baffles and
the chamber bottom. The chamber bottom 2 comprises a radial channel
2r in the zone where the joint cover of the join of the baffles is
placed. This channel 2' makes it possible to arrange a sufficient
air gap when the joint covers have a greater thickness than the
clearance between the flat portion 20a of the baffle and the wall
of the chamber bottom.
[0049] Another variant is shown in FIGS. 12, 13 and 14.
[0050] These show the baffles 30, 30' with a flat wall 30a, 30'a, a
central opening 30b, 30'b, two longitudinal edges 30c, 30'c and
30d, 30'd and two rounded and curved transverse edges 30e, 30'e and
30f, 30'f. The two longitudinal edges 30c, 30d; 30'c, 30'd each
comprise a tongue 30c1, 30d1; 30'c1, 30'd1 parallel to the wall of
the baffle and arranging a groove-shaped housing 30c10g and 30d10g,
30'c10g, 304d10g. The grooves are arranged so as to interact with a
metal fitted tongue 31. Therefore the tongue is housed in the
adjacent grooves 30d10g and 30'c10g. The clearance is sufficient to
allow the expansion of the combustion chamber during the different
engine speeds while maintaining a sealed contact between the edge
20'c and the sides of the groove 20d10g.
* * * * *