Backwound of the invention
The present invention relates to the general field of turbine
engine combustion chambers. It focuses more particularly on an annular
5 wall for direct or reverse-flow combustion chamber cooled by a process
known as ccmultiperforationn.
Typically, an annular turbine engine combustion chamber is
formed by an internal annular wall and an external annular wall which are
connected upstream by a transversal wall forming the chamber base.
10 The internal and external annular walls are each provided with a
plurality of various holes and orifices enabling circulating air around the
combustion chamber to penetrate inside the latter.
In this way, holes called << primary >> and << dilution >> are formed
in these annular walls to convey air inside the combustion chamber. The
15 air using the primary holes contributes to creating an airlfuel mixture
which is burnt in the chamber, while the air originating from the dilution
holes is intended to favour dilution of this same airlfuel mixture.
The internal and external annular walls undergo high
temperatures of gas originating from the combustion of the airlfuel
20 mixture.
. To ensure their cool~ng, additional so-called multiperforation --
orifices are also bored through these annular walls over their entire
surface. These multiperforation orifices, inclined generally at 60°, allow
the circulating air outside the chamber to penetrate inside the latter for
25 forming cooling air films along the walls.
However, in practice, it has been noted that the zone of the
internal and external annular walls which is situated directly downstream
of each of the primary or dilution holes, due especially to the absence of
orifices resulting from the laser boring technology used, benefits from a
30 low level of cooling with the risk of cracks forming, as this implies.
To resolve this problem, document US 6 145 319 proposes
making transition holes in the wall zone located directly downstream of
each of the primary and dilution holes, these transition holes having less
inclination than that of the multiperforation orifices. However, given that
35 this is localised treatment, this solution regrettably proves particularly
costly and significantly prolongs manufacture of the walls.
Object and summarv of the invention
The aim of the present invention is to rectify such disadvantages
by proposing an annular combustion chamber wall which ensures
5 adequate cooling of the zones located directly downstream of the primary
and dilution holes.
For this purpose, an annular turbine engine combustion
chamber wall is provided, comprising a cold side and a hot side, said
annular wall comprising:
10 . a plurality of primary holes distributed according to a circumferential row
to allow circulating air of the cold side of said annular wall to enter the hot
side to create an air/fuel mixture;
. a plurality of dilution holes distributed according to a circumferential row
to allow circulating air of the cold side of said annular wall to enter the hot
15 side to ensure dilution of the air/fuel mixture; and
. a plurality of cooling orifices to allow circulating air of the cold side of
said annular wall to enter the hot side to form a film of cooling air along
said annular wall, said cooling orifices being distributed according to a
plurality of circumferential rows spaced axially from one another and the
20 geometric axes of each of said cooling orifices being inclined, in an axial
direction D of flow of combustion gases, by an angle of inclination 81
relative to a normal N to said annular wall;
characterised in that it further comprises a plurality of additional cooling
orifices arranged on the one hand directly downstream of said primary
25 holes and on the other hand directly downstream of said dilution holes
and distributed according to a plurality of circumferential rows spaced
axially from one another,
the geometric axes of each of said additional cooling orifices being
arranged in a plane perpendicular to said axial direction D and inclined by
30 an angle of inclination 82 relative to a normal N to said annular wall.
The presence of additional cooling orifices arranged inclined in a
plane perpendicular to the direction of flow of combustion gases, directly
downstream and close to the primary and dilution holes, ensures
efficacious cooling relative to classic axial multiperforation where the film
35 of air is stopped by the presence of these holes, and without modifying
the flow in the primary zone.
Preferably, it further comprises at the level of a transition zone
formed downstream of said plurality of rows of additional orifices at least
two rows of orifices whereof the geometric axes of each of said orifices
are inclined, relative to a plane perpendicular to said axial direction D, by
5 an inclination determined as different for each of said two rows.
According to another embodiment, the annular turbine engine
combustion chamber wall comprising a cold side and a hot side can also
comprise:
. a plurality of primary holes or dilution holes distributed according to a
10 circumferential row to allow circulating air of the cold side of said annular
wall to enter the hot side to respectively create an air/fuel mixture or
ensure dilution of the air/fuel mixture; and
. a plurality of cooling orifices to allow the circulating air of the cold side of
said annular wall to enter the hot side to form a film of cooling air along
15 said annular wall, said cooling orifices being distributed according to a
plurality of circumferential rows spaced axially from one another and the
geometric axes of each of said cooling orifices being inclined, in an axial
d~rection D of flow of combustion gases, by an angle of inclination 81
relative to a normal N to said annular wall;
20 characterised in that it further comprises a plurality of additional cooling
orifices arranged directly downstream of said primary holes or dilution and
distributed according to a plurality of circumferential rows spaced axially
from one another,
the geometric axes of each of said additional cooling orifices being
25 arranged in a plane perpendicular to said axial direction D and inclined by
an angle of inclination 82 relative to a normal N to said annular wall,
and in that it further comprises at the level of a transition zone formed
downstream of said plurality of rows of additional orifices at least two
rows of orifices whereof the geometric axes of each of said orifices are
30 inclined, relative to a plane perpendicular to said axial direction D, by an
inclination determined as different for each of said two rows.
By smoothing out flows this gyratory-axial multiperforation
transition zone reduces the thermal gradient at the origin of the onset of
cracks. The average temperature profile at the chamber output is
35 improved due to the resulting more effective mixture.
According to an advantageous embodiment of the invention,
said inclination 02 of said additional orifices relative to the normal N to
said annular wall is identical to that 81 of said cooling orifices.
Advantageously, a diameter d2 of said additional orifices is
5 identical to a diameter d l of said cooling orifices and a pitch p2 of said
additional orifices is identical to a pitch p l of said cooling orifices and said
additional orifices can have greater densification just downstream of the
primary holes and the dilution holes.
When it comprises these two rows of orifices, said inclinations
10 are 30° and 60° respectively. Said two rows of orifices are then either two
rows of additional orifices arranged immediately upstream of a row of
cooling orifices, or two rows of cooling orifices arranged immediately
downstream of a row of additional orifices, or a row of additional orifices
and an adjacent row of cooling orifices.
15 When it comprises several rows of orifices, said inclinations are
distributed regularly between O0 and 90°.
Advantageously, the direction of inclination of said additional
orifices is restricted by the direction of flow of the air/fuel mixture
downstream of said combustion chamber.
20 Another aim of the present invention is a combustion chamber
and a turbine engine (having a combustion chamber) comprising an
annular wall such as defined previously.
Brief descri~tiono f the diaarams
. ~
, - , ~. . . 25~ Other characteristics and advantages-of . the -present invention - ~
will emerge from the followingdescription, in reference to the attached
diagrams which illustrate an embodiment devoid of any limiting character.
In the figures:
- Figure 1 is a view in longitudinal section of a turbine engine combustion
30 chamber in its environment;
- Figure 2 is a partial and developed view of one of the annular walls of
the combustion chamber of Figure 1 according to an embodiment of the
invention; and
- Figure 3 is a partial perspective view of part of the annular wall of Figure
35 2.
, ..
Detailed descri~tiono f the invention
Figure 1 illustrates in its environment a combustion chamber 10
for a turbine engine. Such a turbine engine comprises especially a
compression section (not shown) in which air is compressed prior to being
5 injected into a chamber housing 12, then into the combustion chamber 10
mounted inside the latter. The compressed air is introduced to the
combustion chamber and mixed with fuel prior to being burnt. The gases
coming from this combustion are directed to a high-pressure turbine 14
arranged at the outlet of the combustion chamber.
10 The combustion chamber is of annular type. It is formed by an
internal annular wall 16 and an external annular wall 18 which are joined
upstream by a transversal wall 20 forming the chamber base. It can be
direct as illustrated or reverse-flow. In this case, a return elbow which can
also be cooled by multi-dr~llingis placed between the combustion chamber
15 and the turbine distributor.
The annular internal 16 and external 18 walls extend according
to a longitudinal axis slightly inclined relative to the longitudinal axis 22 of
the turbine engine. The chamber base 20 is provided with a plurality of
openings 20A in which are mounted fuel injectors 24.
20 With the combustion chamber 10 the chamber housing 12,
which is formed by an internal envelope 12a and an external envelope
12b, forms annular spaces 26 which admit compressed air intended for
combustion, dilution and cooling of the chamber.
The annular internal 16 and external 18 walls each exhibit a cold
25 side 16a, 18a arranged to the side of the annular space 26 in which
compressed air circulates and a hot side 16b, 18b turned towards the
interior of the combustion chamber (Figure 3).
The combustion chamber 10 is divided into a zone called <<
primary >> (or combustion zone) and a zone called cr secondary ,, (or
30 dilution zone) located downstream of the preceding one (downstream
means relative to a general axial direction of flow of gases coming from
the combustion of the air/fuel mixture inside the combustion chamber and
materialised by arrow D).
The air which feeds the primary zone of the combustion
35 chamber is introduced via a circumferential row of primary holes 28 made
in the annular internal 16 and external 18 walls of the chamber over the
entire circumference of these annular walls. These primary holes comprise
a downstream edge aligned with the same line 28A. As for the air feeding
the secondary zone of the chamber, it uses a plurality of dilution holes 30
also formed in the annular internal 16 and external 18 walls over the
5 entire circumference of these annular walls. These dilution holes 30 are
aligned according to a circumferential row which is offset axially
downstream relative to the rows of primary holes 28 and they can have
different diameters especially with alternating large and small holes. In the
configuration illustrated in Figure 2, these dilution holes of different
10 diameters however have a downstream edge aligned with the same line
30A.
To cool the annular internal 16 and external 18 walls of the
combustion chamber which are subjected to high temperatures from the
combustion gases, a plurality of cooling orifices 32 is provided (illustrated
15 in Figures 2 and 3).
These orifices 32, which ensure cooling of the walls 16, 18 by
multiperforation, are distributed according to a plurality of circumferential
rows spaced axially from one another. These rows of multiperforation
orifices cover the entire surface of the annular walls of the chamber with
20 the exception of particular zones forming the object of the invention
precisely delimited and between the line 28A, 30A forming an upstream
transition axis and a downstream transition axis offset axially downstream
relative to this axis upstream and either substantially in front of the
dilution holes (for the downstream axis 288) or substantially in front of the
25 outlet plane of the chamber (for the downstream axis 308).
The number and diameter d l of the cooling orifices 32 are
identical in each of the rows. The pitch p i between two orifices of the
same row is constant and can be identical or not for all rows. Also, the
adjacent rows of cooling orifices are arrows so that the orifices 32 can be
30 arranged staggered as shown in Figure 2.
As illustrated in Figure 3, the cooling orifices 32 generally have
an angle of inclination 81 relative to a normal N to the annular wall 16, 18
through which they are made. This inclination 81 allows the air using
these orifices to form a film of air along the hot side 16b, 18b of the
35 annular wall. Relative to the non-inclined orifices, it increases the surface
of the annular wall which is cooled. Also, the inclination 81 of the cooling
orifices 32 is directed such that the resulting film of air flows in the
direction of flow of the combustion gases inside the chamber (indicated by
arrow D).
By way of example, for an annular wall 16, 18 made of metallic
5 or ceramic material and having a thickness of between 0.6 and 3.5 mm,
the diameter d l of the cooling orifices 32 can be between 0.3 and 1 mm,
the pitch d l between 1 and 10 mm and their inclination 81 between +30°
and +70°, typically +60°. By way of comparison, for an annular wall
having the same characteristics, the primary holes 28 and the dilution
10 holes 30 have a diameter of the order of 4 to 20 mm.
According to the invention, each annular wall 16, 18 of the
combustion chamber comprises, arranged directly downstream of the
primary holes 28 and dilution holes 30 and distributed according to several
circumferential rows, typically at least 5 rows, from the upstream
15 transition axis 28A, 30A and as far as the downstream transition axis 288,
308, a plurality of additional cooling orifices 34. However, compared to the
previous cooling orifices which deliver a f~lmo f air flowing in the axial
direction D, the film of air delivered by these additional orifices flows in a
perpendicular direction due to their disposition in a plane perpendicular to
20 this axial direct~on D of flow of combustion gases. This multiperforation
performed perpendicularly to the axis of the turbine engine (throughout
description this will be referred to as gyratory multiperforation as opposed
to axial multiperforation of the cooling orifices) brings together the
additional orifices of the primary or dilution holes and improves the
25 efficacy of the air/fuel mixture.
The additional orifices 34 of the same row have the same
diameter d2, preferably identical to the diameter d l of the cooling orifices
32, are spaced at a constant pitch p2 which can be identical or not to the
pitch p l between the cooling orifices 32 and have an inclination 82,
30 preferably identical to the inclination 81 of the cooling orifices 32 but
arranged in a perpendicular plane. However, while they are still within the
ranges of values defined previously, these characteristics of the add~tional
orifices 34 can be substantially different to those of the cooling orifices 32,
that is, the inclination 82 of the additional orifices of the same row relative
35 to a normal N to the annular wall 16, 18 can be different to that 81 of the
cooling orifices, and the diameter d2 of the additional orifices of the same
row can be different to that d l of the cooling orifices 32.
However, according to the preferred cooling need, the additional
orifices 34 behind the row of primary holes 28 can also advantageously
5 have characteristics in terms of inclination, diameter or pitch different to
those arranged behind the row of dilution holes 30 and, more particularly,
within the same zone a difference in the diameter d2 and pitch p2 can
also be made to densify this cooling in the most thermally constrained
parts, that is, those just downstream of the primary holes and the large
10 dilution orifices, when the latter are formed by alternating large and small
orifices, as illustrated in Figure 2.
Between the row of primary holes and that of the dilution holes,
the introduction of gyratory multiperforation prevents the formation of
cracks downstream of the primary holes 28 by limiting the elevation of the
15 thermal gradient. Since the upstream multiperforation of the dilution holes
30 from the downstream transition axis 288 is of axial type, it is necessary
to provide a transition zone made for example over two rows in which the
additional cooling holes 34 are each arranged in a plane inclined with one
at 30° and the other at 60° relative to the axial direction D, the other
20 parameters, specifically the diameter d2, the pitch p2 and the inclination
82 of these additional holes in these inclined planes remaining unchanged.
Similarly, at the chamber output, more precisely from the
downstream transition axis 308 (Figure 2), introduction of axial
multiperforation meets the local level of gyration so as not to lose the
25 high-pressure turbine (TuHP) output of the combustion chamber.
Preferably, it is also advisable to provide a gyratory-axial multiperforation
transition zone for smoothing out flows to reduce the thermal gradient at
the origin of the onset of cracks. The average temperature profile at the
chamber output is improved due to the resulting more effective mixture.
30 This transition zone can for example be made over two rows of additional
cooling holes, each arranged in a plane inclined with one at 30° and the
other at 60° relative to the axial direction D, the other parameters,
specifically the diameter d2, the pitch p2 and the inclination 82 of the
additional holes in these inclined planes remaining unchanged. In the case
35 of a reverse-flow combustion chamber, this zone from the axis 308 cannot
exist or be integrated in the return elbow.
It is evident that if the transition zone has been described at the
level of gyratory multiperforation, there is no problem placing it at the
level of axial multiperforation or even straddled with a row of axial
multiperforation inclined at 30° and a row of gyratory multiperforation
5 inclined at 60°. Similarly, this transition zone can comprise more than two
rows, the inclination of the orifices then being distributed evenly between
O0 (axial multiperforation) and 90° (gyratory multiperforation). For
example, with three rows, the inclination of the orifices will be respectively
22.5O, 45O and 67.5O.
10 With the invention, the flow in the primary zone is not
modified, and gyration does not impact the orientation of the dilution jets
and omitting the thermal barrier brings a gain in mass and accordingly
cost. It is also evident that to respect the flow directions in the HPD and
avoid aerodynamic delaminations and retain the output of the high-
15 pressure turbine, the direction of boring of the gyratory multiperforation is
fixed by the orientation of the airfoils of the high-pressure distributor
(HPD) downstream of the combustion chamber.

Claims
1. An annular wall (16, 18) of a turbine engine combustion chamber (lo),
comprising a cold side (16a, 18a) and a hot side (16b, 18b), said annular
5 wall comprising:
. a plurality of primary holes (28) distributed according to a circumferential
row to allow circulating air of the cold side (16a, 18a) of said annular wall
to enter the hot side (16b, 18b) to create an alrffuel mixture;
. a plurality of dilution holes (30) distributed according to a circumferential
10 row to allow circulating air of the cold side (16a, 18a) of said annular wall
to enter the hot side (16b, 18b) to ensure dliution of the alrffuel mixture;
and
. a plurality of cooling orifices (32) to allow the circulating air of the cold
side (16a, 18a) of said annular wall to enter the hot side (16b, 18b) to
15 form a fllm of cooling air along said annular wall, said cooling orifices
being distributed accordlng to a plurality of circumferential rows spaced
axially from one another and the geometric axes of each of said cooling
orifices being inclined, in an axial direction D of flow of combustion gases,
by an angle of inclination 81 relative to a normal N to said annular wall;
20 characterised in that it further comprises a plurality of additional cooling
orifices (34) arranged on the one hand directly downstream of said
primary holes and on the other hand directly downstream of said dilution
holes and distributed accordlng to a plurality of circumferential rows
spaced axially from one another,
25 the geometric axes of each of said additional cooling orifices being
arranged in a plane perpendicular to said axial direction D and inclined by
an angle of inclination 82 relative to a normal N to said annular wall.
2. The wall as claimed in Claim 1, characterised in that said inclination 82
30 of said additional orifices relative to the normal N to said annular wall is
identical to that 81 of said cooling orifices.
3. The wall as claimed in Claim 1 or Claim 2, characterised in that a
diameter d2 of said additional orifices is identical to a diameter d l of said
35 cooling orifices and a pitch p2 of said additional orifices is identical t o a
pitch p l of said cooling orifices.
4. The wall as claimed in Claim 1, characterised in that said additional
orifices exhibit greater densification just downstream of the primary holes
and the dilution holes.
5
5. The wall as claimed in any one of Claims 1 to 4, characterised in that it
further comprises at the level of a transition zone (288, 30B), formed
downstream of said plurality of rows of additional orifices, at least two
rows of orifices whereof the geometric axes of each of said orifices are
10 inclined, relative to a plane perpendicular to said axial direction D, by an
inclination determined as different for each of said two rows.
6. An annular wall (16, 18) of'a turbine engine combustion chamber (lo),
comprising a cold side (%a, 18a) and a hot side (16b, 18b), said annular
15 wall comprising:
. a plurality of primary holes (28) or dilution holes (30) distributed
according to a circumferential row to allow circulating air of the cold side
(16a, 18a) of said annular wall to enter the hot side (16b, 18b) to
respectively create an air/fuel mixture or ensure dilution of the alr/fuel
20 mixture; and
. a plurality of cooling orifices (32) to allow the circulating air of the cold
side (16a, 18a) of said annular wall to enter the hot side (16b, 18b) to
form a film of cooling air along said annular wall, said cooling orifices
being distributed according to a plurality of circumferential rows spaced
- 25 axially from one another and the geometric axes of each of said cooling
orifices being inclined, in an axial direction D of flow of combustion gases,
by an angle of inclination 81 relative to a normal N to said annular wall;
characterised in that it further comprises a plurality of additional cooling
orifices (34) arranged directly downstream of said primary holes or
30 dilution holes and distributed according to a plurality of circumferential
rows spaced axially from one another,
the geometric axes of each of said additional cooling orifices being
arranged in a plane perpendicular to said axial direction D and inclined by
an angle of inclination 82 relative to a normal N to said annular wall,
35 and in that it further comprises at the level of a transition zone (288, 30B)
formed downstream of said plurality of rows of additional orifices, at least
two rows of orifices whereof the geometric axes of each of said orifices
are inclined, relative to a plane perpendicular to said axial direction D, by
an inclination determined as different for each of said two rows.
5 7. The wall as claimed in Claim 5 or Claim 6, characterised in that it
comprises two rows of orifices and said inclinations are 30" and 60"
respectively.
8. The wall as claimed in Claim 7, characterised in that said two rows of
10 orifices are two rows of additional orifices arranged immediately upstream
of a row of cooling orifices, two rows of cooling orifices arranged
immediately downstream of a row of additional orifices, or even a row of
additional orifices and an adjacent row of cooling orifices.
15 9. The wall as claimed in Claim 5 or Claim 6, characterised in that it .
comprises several rows of orifices and said inclinations are distributed
evenly between O0 and 90".
10. The wall as claimed in any one of Claims 1 to 9, characterised in that
20 the direction of inclination of said additional orifices is restricted by the
direction of flow of the airlfuel mixture downstream of said combustion
chamber.
11. A combustion chamber (10) of a turbine engine, comprising at least
;'* 25 one annular wall (16, 18) as claimed in any one of Claims 1 to lo;-;-- .:-
12. A turbine engine comprising a combustion chamber (10) having at
least one annular wall (16, 18) as claimed in any one of Claims 1 to 10.