AN ANNULAR COMBUSTION CHAMBER FOR A TURBINE ENGINE
The present invention relates to an annular
combustion chamber for a turbine engine such as an
airplane turbojet or turboprop.
5 In known manner, an annular combustion chamber for a
turbine engine receives upstream a stream of air from a
high pressure compressor, and delivers downstream a
stream of hot gas for driving the rotors of high-pressure
and low-pressure turbines.
10 An annular combustion chamber comprises two coaxial
walls forming surfaces of revolution extending one inside
the other and connected together at their upstream ends
by an annular chamber end wall, the chamber end wall
having openings for mounting fuel injection systems
15 between the inner and outer coaxial walls.
Each injection system includes means for supporting
the head of a fuel injector and at least one swirler that
is arranged downstream from the head of the injector, on
the same axis, and that delivers a rotating stream of air
20 downstream from the injection of fuel so as to form a
mixture of air and of fuel that is to be burnt in the
combustion chamber.
The swirlers of injection systems are fed with air
coming from an annular diffuser mounted at the outlet
25 from the high-pressure compressor arranged upstream from
the combustion chamber.
Each swirler leads downstream to the inside of a
mixer bowl having a substantially frustoconical
downstream wall that flares downstream and that includes
30 a row of air injection orifices that are regularly
distributed around the axis of the bowl.
The outer coaxial wall of the combustion chamber has
an annular row of primary dilution orifices and at least
one spark plug leading to the inside of the combustion
35 chamber and arranged downstream from the primary dilution
orifices.
In operation, air leaving the high-pressure
compressor flows inside each of the injection systems.
The air/fuel mixture is ejected from each injection
system so as to form a sheet of air and of fuel that is
5 substantially frustoconical, flaring downstream. The
aperture angle of the sheet is a function of the aperture
angle of the frustoconical wall of the mixer bowl and of
the dimensions of the air injection orifices formed in
said frustoconical wall. Thus, the greater the diameter
10 of the orifices in the mixer wall, the greater the flow
rate of air passing through each of the orifices, and the
less the extent to which the sheet of air/fuel mixture
flares.
The primary dilution orifices serve to stabilize the
15 combustion flame in the end of the chamber, and by
diluting the air/fuel mixture they prevent the combustion
flame from separating and penetrating into the high
pressure turbine and damaging components, such as
specifically stator vanes, by forming hot points thereon.
20 In practice, injection systems are configured so
that for each injection system, the air/fuel mixture
sheet crosses or intersects circumferentially the fuel
sheets of the two adjacent injection systems, and does so
upstream from the dilution orifices. This ensures
25 circumferential continuity of the air/fuel mixture
between the injection systems prior to dilution, thereby
serving to guarantee that the flame ignited by the spark
plug(s) propagates all around the circumference of the
combustion chamber.
30 In certain configurations, in particular in socalled
converging combustion chambers in which the outer
and inner coaxial walls are frustoconical walls of
section that taper downstream, or when the number of
injection systems is small, the circumferential pitch
35 between adjacent injection systems is greater. As a
result the sheets of fuel from adjacent injection systems
no longer intersect circumferentially upstream from the
primary dilution orifices, thereby giving rise to
difficulties in propagating the flame circumferentially
between the injectors, and thus reducing the performance
of the combustion chamber.
5 In order to mitigate that drawback, it is not
desirable to increase the number of injectors, since that
would lead to making the turbine engine heavier.
Increasing the aperture angle of the sheets of fuel is
also unsatisfactory, since that would lead to projecting
10 a larger quantity of fuel towards the inner and outer
coaxial walls and to forming hot points on the inner and
outer coaxial walls.
A particular object of the invention is to provide a
simple, inexpensive, and effective solution to the above-
15 mentioned problems, making it possible to avoid the
drawbacks of the prior art.
To this end, the invention provides an annular
combustion chamber comprising two coaxial walls forming
surfaces of revolution, respectively an inner wall and an
20 outer wall, the walls being connected together at their
upstream end by an annular chamber end wall having
openings for mounting injection systems, each comprising
at least one swirler for producing a rotating stream of
air downstream from a fuel injector, and a bowl having a
25 substantially frustoconical wall downstream from the
swirler and formed with an annular row of air injection
orifices for producing a substantially frustoconical and
rotating sheet of a mixture of air and of fuel, the outer
wall having an annular row of primary dilution orifices,
30 the combustion chamber being characterized in that the
orifices of the bowls are distributed and dimensioned in
such a manner that at least some of the sheets of
air/fuel mixture present at least one local enlargement
circumferentially intersecting an adjacent fuel sheet
35 upstream from the primary dilution orifices.
The invention makes it possible to conserve the same
angular aperture angle for the sheets of fuel while
modifying some of the bowls so as to form a local
enlargement of their respective fuel sheets, such a local
enlargement circumferentially intersecting the air/fuel
mixture sheet of an adjacent injection system upstream
5 from the primary dilution orifices.
It is thus possible to guarantee circumferential
continuity of the air/fuel mixture prior to air being
introduced via the primary dilution orifices, thereby
ensuring good circumferential propagation of the
10 combustion flame without adding additional injectors.
-In a first embodiment of the invention, the orifices
of the bowls are regularly distributed around the axes of
the bowls, and some of the orifices in some of the bowls
are smaller in diameter than the other orifices of said
15 bowls, the smaller-diameter orifices being formed over an
angular sector of size and angular position that are
predetermined so as to form a local enlargement of the
sheet of fuel.
Having orifices of smaller diameter over a given
20 sector of some of the bowls makes it possible to reduce
the flow rate of air passing through those orifices. The
air leaving those orifices therefore has a smaller impact
on the air/fuel mixture coming from the upstream swirler,
thus leading to a local increase in the ejection angle of
25 the air/fuel mixture and forming a local enlargement of
the fuel sheet.
According to another characteristic of the
invention, the orifices of the above-mentioned angular
sector of each above-mentioned bowl have a diameter that
30 is at least 40% smaller than the diameter of the other
orifices of the bowl.
In a second embodiment of the invention, at least
some of the bowls have no orifices over an angular sector
of size and angular position that are predetermined so as
35 to form the local enlargement of the sheet of fuel.
Eliminating orifices through the frustoconical wall
of the bowl over a sector makes it possible locally to
increase the ejection angle of the air/fuel mixture
sheet, thereby forming a local enlargement of said sheet
that intersects the fuel sheet from an adjacent injection
system.
5 In another embodiment of the invention, some of the
bowls include two diametrically opposite angular sectors
with orifices of smaller diameter and/or with no
orifices.
With such a configuration, the fuel sheet formed at
10 the outlet from each of these bowls has two diametrically
opposite enlargements on either side of the axis of the
bowl, which enlargements intersect the fuel sheets
generated by the two injection systems situated on either
side of the bowl.
15 The combustion chamber includes at least one spark
plug mounted in an orifice in the outer wall, and the
orifices in the bowl of the injection system situated
closest to the spark plug are distributed and dimensioned
in such a manner that the sheet of air/fuel mixture from
20 said injection system presents another local enlargement
intersecting the axis of the spark plug between the
radially inner end of the spark plug and a point of the
outer periphery of said bowl.
This additional enlargement of the sheet of fuel
25 makes it possible to project the sheet of fuel locally
closer to the inner end of the spark plug, thereby
further facilitating ignition of the air/fuel mixture and
the propagation of the flame.
The bowl situated closest to the spark plug may have
30 orifices of diameter smaller than the other orifices of
said bowl, said orifices of smaller diameter being formed
over an angular sector of dimension and angular position
that are predetermined in such a manner as to form the
enlargement intersecting the axis of the spark plug.
35 The bowl situated closest to the spark plug may also
have no orifices over an angular sector of size and
position that are predetermined so as to form the
enlargement intersecting the axis of the spark plug.
The above-mentioned angular sector(s) extend over
about 20° to about 50°.
5 The invention also provides a turbine engine, such
as an airplane turbojet or turboprop, including a
combustion chamber as described above.
Other advantages and characteristics of the
invention appear from reading the following description
10 made by way of non-limiting example and with reference to
the accompanying drawings, in which:
• Figure 1 is a fragmentary diagrammatic half-view
in axial section of an annular combustion chamber of
known type;
15 • Figure 2 is a fragmentary diagrammatic view on a
larger scale of the zone marked in dashed lines in
Figure 1;
• Figure 3 is a diagrammatic side view of two
injection systems in accordance with Figure 2, and
20 arranged side by side;
• Figure 4 is a diagrammatic view in cross-section
of the sheets of fuel from the injection systems of
Figure 3;
• Figure 5 is a diagrammatic view from downstream of
25 a mixer bowl in a first embodiment of the invention;
• Figure 6 is a diagrammatic side view of an
injection system including a mixer bowl in accordance
with Figure 2 and an injection system including a mixer
bowl of the invention as shown in Figure 5;
30 • Figure 7 is a diagrammatic view in cross-section
of the sheets of fuel from the injection systems of
Figure 6;
• Figure 8 is a diagrammatic view from downstream of
a mixer bowl in a second embodiment of the invention;
35 • Figure 9 is a diagrammatic view from downstream of
a mixer bowl in a third embodiment of the invention;
• Figure 10 is a diagrammatic side view of an
injection system including the Figure 9 mixer bowl of the
invention;
• Figure 11 is a diagrammatic cross-section view of
5 the fuel sheet from the injection system of Figure 10;
and
• Figure 12 is a diagrammatic view from downstream
of a mixer bowl in a fourth embodiment of the invention.
Reference is made initially to Figure 1 which shows
10 an annular combustion chamber 10 of a turbine engine such
as an airplane turboprop or turbojet, the combustion
chamber being arranged at the outlet from a centrifugal
diffuser 12 mounted at the outlet from a high-pressure
compressor (not shown). The combustion chamber 10 is
15 followed by a high-pressure turbine 14 of which only the
inlet nozzle 16 is shown.
The combustion chamber 10 has coaxial inner and
outer frustoconical walls 18 and 20 forming surfaces of
revolution that are arranged one inside the other and of
20 section that tapers going downstream. Such a combustion
chamber is said to be convergent. The inner and outer
annular walls 18 and 20 are connected at their upstream
ends to an annular chamber end wall 22 and they are
fastened downstream via inner and outer annular flanges
25 24 and 26. The outer annular flange 26 bears radially
outwards against an outer casing 28 and bears axially
against a radial flange 30 for fastening the nozzle 16 of
the high-pressure turbine to the outer casing 28. The
inner annular flange 24 of the combustion chamber bears
30 radially and axially against an inner annular part 32 for
fastening the nozzle 16 to an inner annular wall 34.
The chamber end wall 22 has openings for mounting
systems for injecting a mixture of air and fuel into the
chamber, the air coming from the centrifugal diffuser 12
35 and the fuel being delivered by injectors 36.
The injectors 36 have their radially outer ends
fastened to the outer casing 28 and they are regularly
#
distributed along a circumference around the axis of
revolution 38 of the chamber. At its radially inner end,
each injector 36 has a fuel injection head 40 that is in
alignment with the axis of a corresponding opening in the
5 chamber end wall 22.
The mixture of air and fuel injected into the
chamber 10 is ignited by means of at least one spark plug
42 that extends radially to the outside of the chamber
10. The inner end of the spark plug 42 extends through
10 an orifice in the outer wall 20 of the chamber, and its
radially outer end is fastened -by appropriate means to
the outer casing 28 and is connected to electrical power
supply means (not shown) situated outside the casing 28.
The outer annular wall 20 of the combustion chamber
15 has an annular row of primary orifices 44 for diluting
the air/fuel mixture, which orifices are arranged
upstream from the spark plug 42.
As can be seen more clearly in Figure 2, each
injection system has upstream and downstream swirlers 46
20 and 48 aligned on the same axis that are connected
upstream to centering and guide means for the head of the
injector, and downstream to a mixer bowl 50 that is
mounted axially in the opening in the chamber end wall
22.
25 Each swirler 46, 48 comprises a plurality of vanes
extending radially around the swirl axis and distributed
regularly around this axis to deliver a rotating stream
of air downstream from the injection head.
The swirlers 46 and 48 are separated from each other
30 by a radial wall 52 connected at its radially inner end
to a Venturi 54 that extends axially downstream inside
the downstream swirler and that separates the flows of
air from the upstream and downstream swirlers 46 and 48.
A first annular air flow stream is formed inside the
35 Venturi 54 and a second annular air flow stream is formed
outside the Venturi 54.
The mixer bowl 50 has a substantially frustoconical
wall 56 that flares downstream and it is connected at its
upstream end to a cylindrical rim 58 extending upstream
and mounted axially in the opening in the chamber end
5 wall 22 together with an annular deflector 60. The
upstream end of the frustoconical wall of the bowl is
fastened via an intermediate annular part 62 to the
downstream swirler.
The frustoconical wall 56 of the bowl has an annular
10 row of air injection orifices 64 regularly distributed
around the axis 70 of the bowl. The air passing through
these orifices and the air flowing in the streams inside
and outside the Venturi 54 become mixed with the fuel
sprayed in by the injector so as to form a rotating sheet
15 of a mixture of air and fuel that is of substantially
frustoconical shape 66, flaring downstream. The axes 68
of each of the air injection orifices 64 of the bowl are
inclined relative to the axis 70 of the bowl converging
downstream towards said axis.
20 A second annular row of orifices 72 is formed at the
junction between the upstream end of the cylindrical rim
58 and the frustoconical wall 56. These second orifices
72 serve to ventilate the downstream face of the •
deflector 60 and they limit the temperature rise of the
25 chamber end wall 22.
In operation, the upstream and downstream swirlers
46 and 48 of the injection system impart rotation on the
stream of air and sprayed fuel, while the air injection
systems 64 in the frustoconical wall 56 of the bowl 50
30 impart shear to the air/fuel mixture. Thus, the greater
the diameter of the air injection orifices 64 in the bowl
50, the greater the rate at which air passes through
these orifices, thereby decreasing the aperture angle 74
of the frustoconical sheet of the air/fuel mixture.
35 In order to ensure circumferential propagation of
the combustion flame between the injection systems, the
configuration and the number of injection systems are
10
determined so that the fuel sheets of adjacent injection
systems intersect or cross in the circumferential
direction upstream from the primary dilution orifices 44
so as to form a circumferentially continuous mist of
5 air/fuel mixture.
Figure 3 shows two adjacent injection systems SI and
S2 and the dashed lines show the frustoconical sheets of
fuel as sprayed by the respective injection systems SI
and S2. Figure 4 shows another pair of sheets of fuel Nl
10 and N2 of the injection systems SI and S2, respectively,
in a transverse plane 76 containing the primary dilution
orifices.
It can be seen that when the number of injection
systems is reduced and the circumferential pitch between
15 two adjacent injection systems SI and S2 increases, the
pitch becomes too great for the fuel sheets Nl and N2 to
intersect circumferentially upstream from the primary
dilution orifices, and that leads to difficulties in
ensuring that the combustion flame propagates
20 circumferentially.
In order to mitigate that drawback, it is not
desirable to increase the aperture angle of the fuel
sheets, since that would lead to a larger quantity of
fuel being sprayed towards the inner and outer annular
25 walls 18 and 20, thereby leading to hot points being
formed on the inner and outer annular walls 18 and 20 of
the combustion chamber. Nor is it desirable to increase
the number of injection systems, since that would lead to
making the turbine engine heavier and to increase in its
30 fuel consumption.
The invention provides a solution to this problem,
and also to the problems mentioned above, by distributing
and dimensioning the orifices in the bowls of the
injection systems in such a manner as to enlarge the fuel
35 sheets locally in a circumferential direction so that,
upstream from the primary dilution orifices, they
11
intersect the sheets of fuel produced by the adjacent
injection systems.
In a first embodiment of the invention as shown in
Figure 5, the mixer bowl 78 seen from downstream has a
5 plurality of orifices 80 that are regularly distributed
around the axis 82 of the bowl. The bowl 78 has an
angular sector 84 with orifices 86 of a diameter smaller
than the diameter of the other orifices 80 in the bowl
78.
10 When the air/fuel mixture penetrates into the inside
of the bowl 78, the flow rate of air passing through the
orifices 86 in the sector 84 is smaller than the flow
rate of air passing through the other orifices 80 of the
bowl 78. As a result, the particles of air and fuel
15 passing in the vicinity of this sector 84 of the bowl 78
leaves the bowl 78 on a path that is more flared than
that of the particles passing in the vicinity of the
other orifices 80 of the bowl 78. This leads to the
sheet of sprayed fuel being enlarged locally.
20 As mentioned above, the sheet of the air/fuel
mixture leaving each injection system is rotating because
of the rotation imparted by the upstream and downstream
swirlers. Thus, each particle of air and of fuel in the
air/fuel sheet follows a path that is substantially
25 helical and frustoconical. The local enlargement takes
on a shape corresponding to these helical and
frustoconical paths.
When the upstream and downstream swirlers produce a
stream of air rotating counterclockwise on looking at the
30 bowl from downstream, it can be understood that the
sector 84 of the bowl 78 should be angularly offset by an
angle a in the direction opposite to the direction of
rotation of the air/fuel mixture, i.e. clockwise,
relative to a plane 87 containing the axis 82 of the bowl
35 78 and perpendicular to a radial plane 89 containing the
axis 82 of the bowl 78 and the axis of the combustion
chamber. In Figure 5, the planes 87 and 89 are
12
represented by lines and they are perpendicular to the
plane of the sheet. The angle a is measured from the
middle of the sector of the bowl 78 containing the
orifices 86 of smaller diameter. This angle a determines
5 the position (arrow A) of the enlargement of the fuel
sheet that will intersect circumferentially the fuel
sheet from an adjacent injection system.
Figure 6 shows two adjacent injection systems, one
of which, SI, is identical to that of the prior art
10 described with reference to Figure 3, and the other of
which, S3., corresponds to the injection system described
with reference to Figure 5. The dashed lines show the
frustoconical shapes of the fuel sheets Nl and N2
produced by each of the injection systems SI and S3. The
15 enlargement 88 of the fuel sheet N3 from the injection
system S3 intersects the fuel sheet Nl from the injection
system SI circumferentially upstream from the primary air
injection orifices. Figure 7 is a section view through
the fuel sheets Nl and N3 of the injection systems SI and
20 S3, respectively, in a transverse plane 76 containing the
primary dilution orifices. In this figure, it can be
seen that the local enlargement 88 of the sheet N3 of the
air/fuel mixture from the injection system S3 intersects
the sheet Nl from the injection system SI
25 circumferentially.
The angular extent of the sector 84 of the bowl 78
determines the angular extent of the enlargement around
the axis 82 of the bowl 78.
In a second embodiment of the invention, the sector
30 of the bowl having smaller-diameter orifices is replaced
by a sector 90 having no air injection orifices, as shown
in Figure 8. This sector 90 without orifices is likewise
offset by an angle a relative to the plane 87. Such a
bowl 92 makes it possible to obtain a fuel sheet having
35 substantially the same shape as that obtained with a bowl
78 having a sector 84 of smaller-diameter orifices 86.
Only the width of the enlargement of the fuel sheet is
13
greater because there is no flow of air passing through
the sector 90 of the bowl 92.
In a practical implementation of the embodiment
shown in Figures 5 and 8, the sector 84 of the bowl 78
5 having smaller-diameter orifices and the sector 90 of the
bowl'92 having no orifices extends angularly over about
50° and the angle a is about 120°.
In another embodiment of the invention as shown in
Figure 9, the mixer bowl 94 has two diametrically
10 opposite angular sectors 96 and 98 that have no air
injection orifices. Arrows B and C show the paths
followed by the particles of air and fuel passing in the
vicinity of the first and second sectors 96 and 98 of the
bowl 94.
15 Figure 10 shows an injection system S4 having a bowl
94 with two of the above-mentioned diametrically opposite
sectors. The first and second sectors 96 and 98 of the
bowl 94 serve to form a first enlargement 100 and a
second enlargement 102 of the fuel sheet N4 (Figures 10
20 and 11). These first and second enlargements 100, 102
are diametrically opposite each other and they are for
intersecting circumferentially the fuel sheets produced
by the injection systems situated on either side of the
bowl 94.
25 In a practical implementation of the Figure 9 bowl,
each sector 98, 96 extends angularly over about 20° to
30° and is angularly offset by an angle of about 100° in
the opposite direction to the direction of rotation of
the air/fuel mixture, i.e. clockwise, relative to a plane
30 95 containing the axis 97 of the bowl 94 and
perpendicular to a radial plane 99 containing the axis 97
of the bowl 94 and the axis of the combustion chamber.
In Figure 9, the planes 95 and 99 are represented by
lines and they are perpendicular to the plane of the
35 sheet.
In a variant embodiment of the Figure 9 bowl, the
two diametrically opposite angular sectors may have
14
orifices of smaller diameter. It is also possible for
one of the sectors to have no orifices, while the other
sector has orifices of smaller diameter.
In yet another embodiment of the invention as shown
5 in Figure 12, the mixer bowl 104 situated closest to the
spark plug 42 has two angular sectors 106, 108 with no
orifices, one of which sectors, 106, serves to form a
first enlargement for intersecting circumferentially an
adjacent fuel sheet, while the other enlargement, 108,
10 serves to form a second enlargement for intersecting the
axis 110 of the spark plug 42 between the inner end of
the spark plug and a point of the outer periphery of the
bowl 104.
The first and second enlargements are substantially
15 located on the fuel sheet at 90° relative to each other.
The arrows D and E show the paths followed by the
particles of air and of fuel passing in the vicinity of
the first and second sectors of the bowl 104.
The first angular sector 106 of the bowl 104 extends
20 angularly over about 50°, and the second angular sector
108 for delivering fuel closer to the inner end of the
spark plug 42 extends angularly over about 40°.
The injection system situated closest to the spark
plug may also have two diametrically opposite sectors as
25 described with reference to Figure 10 for the purpose of
circumferentially propagating the combustion flame,
together with a third sector having no orifices or having
orifices of small diameter for delivering fuel towards
the spark plug.
30 In the above description, the direction of rotation
of the swirlers is given by way of example and it could
be understood that the operation would be similar for an
air/fuel mixture rotating clockwise. Under such
circumstances, only the angular positioning of the
35 sectors of the bowls without orifices or with orifices of
smaller diameter would need to be modified.
15
In practice, the positioning and the angular extent
of the sector having orifices of smaller diameter or
having no orifices is determined by three-dimensional
simulation. Such a simulation takes account of numerous
5 parameters such as the shape and the angle of inclination
of the vanes of the swirlers the direction of rotation of
the swirlers, the flow rate of air from the high pressure
compressor, and the flow rate of fuel from the injectors,
etc.
10 The mixer bowl of the invention makes it possible to
obtain-circumferential continuity for the air/fuel
mixture between two injectors prior to air being
introduced via the primary dilution orifices, thereby
ensuring good circumferential propagation of the
15 combustion flame when the number of injection systems is
smaller and/or when the circumferential pitch between
those systems is greater.

0 ^ 5. iV
CLAIMS
1. An annular combustion chamber (10) for a turbine
engine, the chamber comprising two coaxial walls forming
surfaces of revolution, respectively an inner wall (18)
5 and an outer wall (20), the walls being connected
together at their upstream end by an annular chamber end
wall (22) having openings for mounting injection systems,
each comprising at least one swirler (46, 48) for
producing a rotating stream of air downstream from a fuel
10 injector (36), and a bowl (78, 92, 94, 104) having a
substantially frustoconical wall downstream from the
swirler and formed with an annular row of air injection
orifices (80, 86) for producing a substantially
frustoconical and rotating sheet of a mixture of air and
15 of fuel, the outer wall having an annular~rpw",of primary
dilution orifices (44), the combustion chamber b^ing
characterized in that the orifices (80, 86) of the bowls
(78, 92, 94, 104) are distributed and dimensioned in such
a manner that at least some of the sheets (N3, N4) of
20 air/fuel mixture present at least one local enlargement
(88, 100, 102) circumferentially intersecting an adjacent
fuel sheet upstream from the primary dilution orifices
(44).
25 2. A chamber according to claim 1, characterized in that
the orifices (80, 86) of at least some bowls (78) are
regularly distributed around the axes (82) of the bowls
(78), and in that some of the orifices (86) of each of
the bowls are of diameter smaller than the other orifices
30 (80) of said bowls, the smaller-diameter orifices (86)
being formed over an angular sector (84) of size and
angular position that are predetermined so as to form the
local enlargement (88) of the sheet (N3) of fuel.
35 3. A chamber according to claim 2, characterized in that
the orifices (86) of the above-mentioned angular sector
17
of each bowl have a diameter that is at least 40% smaller
than the diameter of the other orifices of the bowl.
4. A chamber according to claim 1.or claim 2,
5 characterized in that at least some of the bowls (92,
104) have no orifices over an angular sector of size and
angular position that are predetermined so as to form the
local enlargement of the sheet of fuel.
10 5. A chamber according to any one of claims 2 to 4,
characterized in that some of the bowls include two
diametrically opposite angular sectors (96, 98) with
orifices of smaller diameter and/or with no orifices.
15 6. A chamber according to any preceding claim,
characterized in that it includes at least one spark plug
(42) mounted in an orifice in the outer wall (20), and in
that the orifices in the bowl (104) of the injection
system situated closest to the spark plug are distributed
20 and dimensioned in such a manner that the sheet of
air/fuel mixture from said injection system presents
another local enlargement intersecting the axis of the
'spark plug between the radially inner end of the spark
plug (42) and a point of the outer periphery of said bowl
25 (104).
7. A chamber according to claim 6,. characterized in that
said bowl situated closest to the spark plug has orifices
of diameter smaller than the other orifices of said bowl,
30 said orifices of smaller diameter being formed over an
angular sector of dimension and angular position that are
predetermined in such a manner as to form the enlargement
intersecting the axis of the spark plug.
35 8. A chamber according to claim 6, characterized in that
said bowl (104) situated closest to the spark plug has no
orifices over an angular sector of size and position that
ft LM
-V^t^ ^^
are predetermined so as to form the enlargement
intersecting the axis (110) of the spark plug (42).
9. A chamber according to any one of claims 2 to 5, 7,
5 and 8, characterized in that the above-mentioned angular
sector(s) (84', 90, 96, 98, 106, 108) extend over about
20° to about 50°.
10. A turbine engine, such as an airplane turbojet or
10 turboprop, including a combustion chamber according to
, , any preceding claim.