U.S. patent application number 14/950518 was filed with the patent office on 2016-06-02 for annular deflection wall for a turbomachine combustion chamber injection system providing a wide fuel atomization zone.
The applicant listed for this patent is Snecma. Invention is credited to Alain Cayre, Yoann Mery.
Application Number | 20160153662 14/950518 |
Document ID | / |
Family ID | 52988156 |
Filed Date | 2016-06-02 |
United States Patent
Application |
20160153662 |
Kind Code |
A1 |
Cayre; Alain ; et
al. |
June 2, 2016 |
ANNULAR DEFLECTION WALL FOR A TURBOMACHINE COMBUSTION CHAMBER
INJECTION SYSTEM PROVIDING A WIDE FUEL ATOMIZATION ZONE
Abstract
A deflection wall known as <<venturi>> is disclosed
to improve the air fuel mix within an injection system installed in
a turbomachine combustion chamber, having a downstream edge formed
by the repetition of a pattern extending on each side of a virtual
circle and formed from a plurality of bosses each of which is
centred relative to a corresponding plane inclined by an angle
.alpha. from a corresponding median axial plane of the annular
deflection wall passing through a corresponding end of the
downstream edge of the annular deflection wall at the boss
considered.
Inventors: |
Cayre; Alain; (Pamfou,
FR) ; Mery; Yoann; (Paris, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Snecma |
Paris |
|
FR |
|
|
Family ID: |
52988156 |
Appl. No.: |
14/950518 |
Filed: |
November 24, 2015 |
Current U.S.
Class: |
60/737 |
Current CPC
Class: |
F23R 3/30 20130101; F23R
3/286 20130101; F23D 2900/11101 20130101 |
International
Class: |
F23R 3/28 20060101
F23R003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2014 |
FR |
14 61658 |
Claims
1. An annular deflection wall for a turbomachine combustion chamber
injection system centred on a longitudinal axis and having a free
downstream edge, said annular deflection wall comprising a
plurality of first bosses projecting radially outwards and a
plurality of second bosses projecting radially inwards and arranged
alternately with said first bosses, such that the downstream edge
of the annular deflection wall, that is formed from a set of
downstream ends from said first and second bosses respectively,
forms an undulation about a virtual circle, said downstream edge
being thus formed by the repetition of a pattern extending on each
side of the virtual circle, wherein each of said first and second
bosses is centred relative to a corresponding plane inclined by an
angle .alpha. from a corresponding median axial plane of the
annular deflection wall passing through a corresponding extremum of
the downstream edge of the annular deflection wall at the boss
considered.
2. The annular deflection wall according to claim 1, wherein said
virtual circle is inscribed inside a virtual extension of a portion
of revolution of the annular deflection wall.
3. The annular deflection wall according to claim 1, in which the
downstream edge of the annular deflection wall is inscribed in a
transverse plane orthogonal to the longitudinal axis of the annular
deflection wall.
4. An annular air inlet for an injection system of a combustion
chamber of a turbomachine, comprising an annular separation wall
that divides the annular air inlet into an upstream air circulation
space and a downstream air circulation space and that is prolonged
radially inwards by an annular deflection wall according to claim
1.
5. A turbomachine, particularly for an aircraft, comprising at
least one combustion chamber comprising at least one injection
system comprising an annular air inlet according to claim 4.
Description
TECHNICAL DOMAIN
[0001] This invention relates to the domain of turbomachines for
aircraft and more particularly relates to an annular deflection
wall of the type currently known as <<venturi>>, to
form part of a fuel and air injection system in a combustion
chamber within a turbomachine.
STATE OF PRIOR ART
[0002] FIG. 1 appended illustrates a turbomachine 10 for an
aircraft of a known type, for example a twin spool turbojet
comprising in general a fan 12 that will draw in an airflow
dividing downstream from the fan into a core engine flow supplying
the core of the turbomachine and a fan flow bypassing this core.
The turbomachine comprises basically a low pressure compressor 14,
a high pressure compressor 16, a combustion chamber 18, a high
pressure turbine 20 and a low pressure turbine 22. The turbomachine
is surrounded by a nacelle 24 surrounding the flow space 26 of the
fan flow. The turbomachine rotors are installed free to rotate
about a longitudinal axis 28 of the turbomachine.
[0003] FIG. 2 shows the combustion chamber 18 of the turbomachine
in FIG. 1. Conventionally, this combustion chamber that is of the
annular type, comprises two coaxial annular walls, the radially
inner wall 32 and the radially outer wall 34, that extend along the
upstream to downstream direction 36 of the core engine gas flow in
the turbomachine, about the centreline of the combustion chamber
that is coincident with the axis 28 of the turbomachine. These
inner annular 32 and outer annular 34 walls are connected to each
other at their upstream end by an annular chamber dome wall 40 that
extends approximately radially about the axis 28. This annular
chamber dome wall 40 is fitted with injection systems 42
distributed around the axis 28 to enable injection of a premix of
air and fuel centred on an injection axis 44.
[0004] During operation, part 46 of an airflow 48 from the
compressor 16 supplies injection systems 42 while another part 50
of this airflow bypasses the combustion chamber flowing in the
downstream direction along the coaxial walls 32 and 34 of this
chamber and in particular supplies air orifices formed in these
walls 32 and 34.
[0005] FIG. 3 is an axial half-sectional view of one of the
injection systems 42. In general, this injection system comprises a
bushing 54, sometimes called the <<sliding crossing>>,
inside which a fuel injector head 52, an annular air inlet 56 and a
bowl 58, sometimes called the "mixer bowl" are installed. These
elements are centred on the injection axis 44 defined by the fuel
injector head 52.
[0006] Throughout the following description, the
<<upstream>> and <<downstream>> directions
are defined within the injection system with reference to fuel
injection along the injection axis 44.
[0007] The annular air inlet 56 comprises an annular separation
wall 60 that divides the annular air inlet into an upstream air
circulation space 62 and a downstream air circulation space 64.
These two spaces are frequently called <<swirler
sections>>.
[0008] The annular separation wall 60 is prolonged radially inwards
as an annular deflection wall 66, frequently called
<<venturi>>, with a convergent-divergent shaped
internal profile 68, particularly with a neck 70 and an external
profile 72.
[0009] The annular deflection wall 66 has a longitudinal axis
coincident with the injection axis 44.
[0010] Each of the upstream 62 and downstream 64 air circulation
spaces is crossed by fins 74 that spin the air about the injection
axis 44.
[0011] During operation, some of the air 46 supplying the injection
system penetrates into air circulation spaces 62 and 64 of the
annular air inlet 56 and continues its path in the form of an
airflow 76 and 78 respectively along the internal profile 68 and
the external profile 72 of the deflection wall 66.
[0012] Furthermore, fuel is ejected by the injector head 52 in the
form of a cone 80 with an angle .theta. relative to the injection
axis 44.
[0013] A large proportion of this fuel is deposited and forms a
film 82 on the internal profile 68 of the deflection wall 66.
[0014] The fuel is entrained by the airflow circulating in the
downstream direction along this internal profile 68, and runs off
towards the downstream direction on the internal profile 68.
[0015] When the fuel reaches the downstream end of the deflection
wall 66, sometimes called the <<trailing edge>> by
analogy with a wing, the fuel meets the airflow 78 passing along
the external profile 72 of the deflection wall 66. This airflow 78
induces a shear effect that makes the fuel separate from the
deflection wall, forming droplets in suspension in the air.
[0016] The fuel droplets separated from the annular deflection wall
evaporate in air, preferably before reaching the inlet to the
combustor in the combustion chamber.
[0017] The evaporation of droplets is facilitated as much as
possible by turbulence induced by the confluence of the airflows 76
and 78 circulating on each side of the annular deflection wall.
[0018] However, this type of injection system is not optimum,
because the extent of the downstream edge of the annular deflection
wall that forms the fuel atomization zone is limited.
[0019] Consequently, the combustion efficiency is itself
limited.
PRESENTATION OF THE INVENTION
[0020] The main purpose of the invention is to provide a simple,
economic and efficient solution to this problem.
[0021] It discloses an annular deflection wall for a turbomachine
combustion chamber injection system centred on a longitudinal axis,
and having a free downstream edge.
[0022] Said downstream edge is formed by the repetition of a
pattern extending on each side of a virtual circle.
[0023] Repetition of such a pattern increases the size of the fuel
atomization zone formed by the downstream edge of the annular
deflection wall.
[0024] The invention can also improve the air and fuel mix and
therefore improve the combustion efficiency.
[0025] In particular, the invention can reduce the lean flameout
richness and reduce CO/CH emissions.
[0026] More precisely, the annular deflection wall comprises a
plurality of first bosses projecting radially outwards and a
plurality of second bosses projecting radially inwards and arranged
alternately with said first bosses, such that the downstream edge
of the annular deflection wall that is formed from a set of
downstream ends from said first and second bosses respectively,
forms an undulation about said virtual circle.
[0027] The first and second bosses not only increase the size of
the downstream edge and therefore the fuel atomization zone, but
these bosses also increase the air/fuel exchange surface area on
the internal surface of the annular deflection wall.
[0028] According to the invention, each of said first and second
bosses is centred relative to a corresponding plane inclined from a
corresponding median axial plane of the annular deflection wall
passing through a corresponding extremum of the downstream edge of
the annular deflection wall at the boss considered.
[0029] Preferably, the downstream edge of the annular deflection
wall is inscribed in a plane orthogonal to the longitudinal axis of
the annular deflection wall.
[0030] Preferably, said virtual circle is inscribed inside a
virtual extension of a portion of revolution of the annular
deflection wall.
[0031] The invention also relates to an annular air inlet for a
turbomachine combustion chamber injection system comprising an
annular separation wall that separates the annular air inlet into
an upstream air circulation space and a downstream air circulation
space that is extended radially inwards by an annular deflection
wall of the type described above.
[0032] The invention also relates to an injection system for a
turbomachine combustion chamber, comprising an annular air inlet of
the type described above.
[0033] Preferably, the injection system also comprises a bushing to
centre a fuel injector head arranged on the upstream side of the
annular air inlet, and a bowl arranged on the downstream side of
the annular air inlet.
[0034] The invention also relates to a combustion chamber for a
turbomachine, comprising at least one injection system of the type
described above.
[0035] Finally, the invention relates to a turbomachine,
particularly of an aircraft, comprising at least one combustion
chamber of the type described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The invention will be better understood and other details,
advantages and characteristics of it will become clear after
reading the following description given as a non-limitative example
with reference to the appended drawings in which:
[0037] FIG. 1, already described, is a diagrammatic axial partial
sectional view of a known type of a turbomachine;
[0038] FIG. 2, already described, is a diagrammatic axial partial
sectional view of a combustion chamber of the turbomachine in FIG.
1;
[0039] FIG. 3, already described, is a diagrammatic axial partial
half-sectional view of an injection system installed in the
combustion chamber in FIG. 2;
[0040] FIG. 4 is a perspective diagrammatic partial view of an
annular deflection wall according to a preferred embodiment of the
invention.
[0041] In all these figures, identical references may denote
identical or similar elements.
DETAILED PRESENTATION OF PREFERRED EMBODIMENTS
[0042] FIG. 4 illustrates an annular deflection wall 100 according
to a preferred embodiment of the invention, to substitute for the
annular deflection wall 66 within the injection system 42 in FIG.
3.
[0043] The annular deflection wall 100 is different from the known
type of the annular deflection wall 66, particularly in that the
annular deflection wall 100 has a downstream edge 102 formed by the
repetition of a pattern 104 extending on each side of a virtual
circle 106, as will become clearer in the following.
[0044] The virtual circle 106 is preferably inscribed in a
transvers plane R orthogonal to the longitudinal axis 44 of the
annular deflection wall 100.
[0045] In the example shown, the annular deflection wall 100
generally comprises an upstream annular part 110 that is curved
radially outwards towards the upstream end so as to have an
internal profile 112 that converges in the downstream direction.
This upstream annular part 110 connects to the separation wall 60
of the annular air inlet 56 of the injection system 42, in a manner
similar to that shown in FIG. 3. The annular deflection wall 100
also comprises a downstream annular part 114 (FIG. 4) that has a
free downstream edge that forms the above-mentioned downstream edge
102 of the annular deflection wall 100. This downstream annular
part 114 comprises an upstream part forming a portion of revolution
118 about the longitudinal axis 44 of the annular deflection wall
100. The downstream annular part 114 has an internal surface 115
and an external surface 117.
[0046] In the illustrated embodiment, the portion of revolution 118
is cylindrical in shape. As a variant, this portion of revolution
118 may be tapered in shape.
[0047] In the example illustrated, the virtual circle 106 is
defined along the extension of the portion of revolution 118.
Consequently, when the portion of revolution 118 is cylindrical in
shape, the virtual circle 106 is centred on the longitudinal axis
44 and its diameter is equal to the diameter of the portion of
revolution 118, while when the portion of revolution 118 is tapered
in shape, the virtual circle 106 that is also centred on the
longitudinal axis 44, is inscribed in the cone centred on the
longitudinal axis 44 and inside which the portion of revolution 118
is inscribed.
[0048] The annular deflection wall 100 comprises a plurality of
bosses that are distributed into first bosses 120 projecting
radially outwards and second bosses 122 projecting radially
inwards. The first bosses 120 and the second bosses 122 are
arranged alternately, downstream from the portion of revolution
118.
[0049] The downstream edge 102 of the annular deflection wall 100
is formed by a set of downstream ends 124, 126 of the first and
second bosses 120, 122 respectively. Thus, due to the alternation
of the first bosses 120 and the second bosses 122, the downstream
edge 102 forms an undulation about the virtual circle 106.
[0050] Furthermore, each of the first and second bosses 120, 122 is
centred relative to a plane P2 inclined by an angle .alpha. from a
median axial plane P1 of the annular deflection wall 100 passing
through one end 128 of the downstream edge 102 of the annular
deflection wall at the boss 120, 122 considered.
[0051] In this case, the angle .alpha. is preferably chosen such
that the general direction of the bosses is approximately
coincident with the direction of the airflow put into rotation by
the fins 74 of the annular air inlet 56 (FIG. 3).
[0052] In general, the downstream edge 102 of the annular
deflection wall 100 is preferably inscribed in the transverse plane
R orthogonal to the longitudinal axis 44 of the annular deflection
wall 100, as is clear in FIG. 4.
[0053] In this case, the pattern 104 extends radially on each side
of the virtual circle 106, in other words a part of the pattern 104
extends radially outside the virtual circle 106 while another part
of the pattern 104 extends radially inside the virtual circle
106.
[0054] During operation, some of the air supplying the injection
system penetrates into the upstream and downstream air circulation
spaces of the annular air inlet, as in the injection system
according to prior art shown in FIG. 3, and continues its path
along the internal surface 115 and external surface 117 of the
annular deflection wall 100 (FIG. 4).
[0055] Furthermore, a large proportion of the fuel ejected by the
injector head is deposited and forms a film on the inside surface
115 of the annular deflection wall 100.
[0056] The fuel entrained by the airflow passing along this
internal surface 115 in the downstream direction runs off towards
the downstream direction on this surface.
[0057] When it reaches the downstream edge 102, the fuel meets the
airflow circulating along the external surface 117 of the annular
deflection wall 100. This airflow induces a shear effect that makes
the fuel detach from the annular deflection wall, forming droplets
in suspension in air.
[0058] Due to its shape, the downstream edge 102 has a larger fuel
atomization zone than the downstream edge of a known type of
annular deflection wall.
[0059] Bosses 120 and 122 can also increase the air/fuel exchange
area on the internal surface 115 of the annular deflection wall
100.
[0060] In general, the repetition of a pattern extending on each
side of a virtual circle as disclosed in the invention, can
increase the fuel atomisation zone.
[0061] The invention can thus improve the air and fuel mix and
therefore improve the combustion efficiency.
[0062] In particular, the invention can reduce the lean flameout
richness and reduce CO/CH emissions.
* * * * *