U.S. patent application number 11/103539 was filed with the patent office on 2009-03-19 for turbine ring.
This patent application is currently assigned to SNECMA MOTEURS. Invention is credited to Nicolas Hervy, Marc Marchi, Ludovic Nicollas.
Application Number | 20090074579 11/103539 |
Document ID | / |
Family ID | 34942125 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090074579 |
Kind Code |
A1 |
Hervy; Nicolas ; et
al. |
March 19, 2009 |
TURBINE RING
Abstract
A turbine ring made up of an assembly of a plurality of sectors
forming the outer shroud of the rotor of said turbine. The sectors
are united end to end with interposed sealing systems comprising
tongues housed in slots, said tongues being rectilinear and engaged
in respective rectilinear slots in the radial faces of said
sectors.
Inventors: |
Hervy; Nicolas; (Draveil,
FR) ; Marchi; Marc; (Le Mee, FR) ; Nicollas;
Ludovic; (Vaux Le Penil, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA MOTEURS
Paris
FR
|
Family ID: |
34942125 |
Appl. No.: |
11/103539 |
Filed: |
April 12, 2005 |
Current U.S.
Class: |
416/179 |
Current CPC
Class: |
F01D 11/005 20130101;
F05D 2240/11 20130101 |
Class at
Publication: |
416/179 |
International
Class: |
F01D 5/22 20060101
F01D005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2004 |
FR |
04 03925 |
Claims
1. (canceled)
2. A turbine ring according to claim 17, wherein each sealing
system between two sectors comprises first and second tongues
extending in a chevron configuration from the insides of said
radial faces, said tongues being engaged in slots in said radial
faces defining their relative positions.
3. A turbine ring according to claim 2, wherein each sealing system
includes a third tongue extending substantially from one end to the
other of the adjacent sectors, parallel to the axis of the ring,
and on the outside of said radial faces.
4. A turbine ring according to claim 3, wherein said first tongue
extends between a point situated close to an inlet edge of each
sector, towards the inside, and a point situated close to said
third tongue.
5. A turbine ring according to claim 4, wherein the angle defined
by the directions of said first and third tongues lies in the range
15.degree. to 70.degree..
6. A turbine ring forming a rotor shroud, the ring comprising a
plurality of sectors interconnected end to end with interposed
sealing systems comprising tongues extending between adjacent
sectors, said tongues being housed in slots formed facing each
other in adjacent radial faces of said sectors, wherein each
sealing system includes rectilinear tongues engaged in respective
rectilinear slots in said radial faces, and wherein the slots
formed in each radial face are independent such that said slots do
not communicate with each other, wherein each sealing system
between two sectors comprises first and second tongues extending in
a chevron configuration from the insides of said radial faces, said
tongues being engaged in slots in said radial faces defining their
relative positions; and wherein said second tongue extends from a
first end point situated close to an outlet edge of each sector,
towards the inside, to a second end point situated close to said
first tongue, said second end point being substantially between the
middle of said first tongue and a two-thirds point starting from an
end point of said first tongue close to an inside face of said
sector.
7. A turbine ring forming a rotor shroud, the ring comprising a
plurality of sectors interconnected end to end with interposed
sealing systems comprising tongues extending between adjacent
sectors, said tongues being housed in slots formed facing each
other in adjacent radial faces of said sectors, wherein each
sealing system includes rectilinear tongues engaged in respective
rectilinear slots in said radial faces, and wherein the slots
formed in each radial face are independent, wherein each sector
includes a cooling air flow cavity, wherein each sector includes
air ejection channels extending between said cavity and at least
one radial face of said sector, said channels opening out in said
radial face between an inside edge thereof and said first and
second tongues.
8. A turbine ring according to claim 7, wherein at least some of
the channels extend substantially perpendicularly to said radial
face.
9. A turbine ring according to claim 7, wherein the orifices of
said channels are disposed in a row parallel to the axis of the
ring.
10. A turbine ring according to claim 9, wherein channels situated
at the ends of said row are formed at an angle and diverge relative
to the other channels on going from the cavity towards the radial
face.
11. A turbine ring according to claim 17, wherein the facing slots
of two adjacent radial faces of said sectors house a single
tongue.
12. A turbine, including a ring according to claim 17.
13. A turbine ring according to claim 7, wherein each sealing
system between two sectors comprises first and second tongues
extending in a chevron configuration from the insides of said
radial faces, said tongues being engaged in slots in said radial
faces defining their relative positions.
14. A turbine ring according to claim 13, wherein each sealing
system includes a third tongue extending substantially from one end
to the other of the adjacent sectors, parallel to the axis of the
ring, and on the outside of said radial faces.
15. A turbine ring according to claim 14, wherein said first tongue
extends between a point situated close to an inlet edge of each
sector, towards the inside, and a point situated close to said
third tongue.
16. A turbine ring according to claim 6, wherein each sector having
an inside face in contact with a stream of hot gas.
17. A turbine ring forming a rotor shroud, the ring comprising a
plurality of sectors, each sector having an inside face in contact
with a stream of hot gas, said sectors being interconnected end to
end with interposed sealing systems comprising tongues extending
between adjacent sectors, said tongues being housed in slots formed
facing each other in adjacent radial faces of said sectors, wherein
each sealing system includes rectilinear tongues engaged in
respective rectilinear slots in said radial faces, and wherein the
slots formed in each radial face are independent such that said
slots do not communicate with each other, wherein each sealing
system between two sectors comprises first and second tongues, and
wherein said second tongue extends from a first end point situated
close to an outlet edge of each sector, towards the inside, to a
second end point situated close to said first tongue, said second
end point being substantially between the middle of said first
tongue and a two-thirds point starting from an end point of said
first tongue close to an inside face of said sector.
18. A turbine ring according to claim 17, wherein said first and
second tongues extend in a chevron configuration from the insides
of said radial faces, said tongues being engaged in slots in said
radial faces defining their relative positions.
19. A turbine ring according to claim 17, wherein each sector
comprises an outer face, opposed said inside face, wherein said
tongues are between said inner and outer faces.
20. A turbine ring according to claim 19, wherein each sealing
system between two sectors comprises first, second and third
tongues, said third tongue extending substantially parallel to said
outer face, and said first and second tongues being located between
said third tongue and said inner face.
Description
[0001] The invention relates to a turbine ring forming the outer
shroud of the rotor of said turbine. The invention applies
particularly to a high pressure turbine situated immediately
downstream from the combustion chamber of an airplane turbojet. It
relates more particularly to the interconnection and cooling of the
sectors making up said turbine ring.
BACKGROUND OF THE INVENTION
[0002] In a turbine of the kind mentioned above, driven by gas at
very high temperature, the rotor rotates inside a stationary
turbine ring constituted by a plurality of curved sectors that are
united end to end circumferentially in order to form the rotor
shroud. The temperature of the gas driving the blade wheel is such
that the thermomechanical stresses that are created between the
sectors can lead to deterioration, reducing the lifetime of such
rings. Typically, small cracks and/or flaking can often be observed
on the inside (or "hot") face of the sectors, mainly in the
vicinity of the connections between adjacent sectors.
[0003] To provide the ring with better sealing, reducing leaks of
non-working air, and in order to prevent hot gas being reinserted,
sealing systems are provided between such adjacent sectors, said
systems comprising tongues that extend between the sectors and that
are received in slots formed facing them in the adjacent radial
faces of said sectors.
[0004] For example, a prior art sector 1 shown in FIG. 1 includes a
sealing system comprising four tongues 2-5 received in slots 6, 7,
and 8. The tongue 3 is bent and extends between two slots 6 and 7
that open out into each other and that receive the other tongues 2
and 4 which are straight. It is difficult to machine the slots
accurately, in particular because of the difference in thickness
needed to be able to insert the bent tongue. It is difficult to
position this tongue properly. In addition, the tongue 2 is
received entirely within a slot 6 that is parallel to the hot face
9 of the sector and that is close thereto. Unfortunately, the mere
fact of forming the slot leads to stress concentration zones which,
when situated close to a hot surface, weaken the part and
accelerate deterioration thereof. The invention makes it possible
to eliminate these drawbacks, in particular.
OBJECTS AND SUMMARY OF THE INVENTION
[0005] The invention thus provides firstly a turbine ring forming a
rotor shroud, the ring being of the type constituted by a plurality
of sectors interconnected end to end with interposed sealing
systems comprising tongues extending between adjacent sectors, said
tongues being housed in slots formed facing each other in adjacent
radial faces of said sectors, wherein each sealing system is
constituted by rectilinear tongues engaged in respective
rectilinear slots in said radial faces.
[0006] The fact of making the sealing system from tongues that are
straight simplifies making the slots and facilitates mounting the
tongues therein. In addition, control over the positioning of the
tongues is improved because of the bear against surfaces that are
under better control since they are strictly linear. Overall,
leakage sections are made smaller. A configuration with only three
tongues is described below.
[0007] More particularly and advantageously, in the above-defined
turbine ring, each sealing system comprises a first tongue and a
second tongue extending in a chevron configuration on the inside of
said radial faces, said tongues being engaged in rectilinear slots
of said radial faces defining their relative positions accurately.
As a result, air leakage between two consecutive sectors can be
accurately calibrated. Such leakage can thus be identical through
all of the inter-sector spaces. Overall, it is estimated that the
leakage rate can be reduced by 10% to 20% compared with the
above-described prior art configuration.
[0008] Another advantage of the invention lies in the fact that
arranging the tongues in a chevron configuration on the hot face
side makes it possible both to move the stress concentration zones
further away from said hot face (since the slots go away
therefrom), and also to provide sufficient space between the
tongues and the hot face to allow cooling air ejection channels to
open out therein, which channels are fed from a cavity formed
within the sector itself.
[0009] More precisely, the invention also provides a turbine ring
as defined above in which each sector includes a cooling air flow
cavity, the ring further including air ejection channels extending
between said cavity and at least one radial face of the sector,
these channels opening out in said radial face between an inner
edge thereof and said first and second tongues.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention will be better understood and other advantages
thereof will appear more clearly in the light of the following
description given purely by way of example and made with reference
to the accompanying drawings, in which:
[0011] FIG. 1 shows a radial face of a sector used in building up a
prior art turbine ring;
[0012] FIG. 2 shows a radial face of a sector used in building up a
tongue ring in accordance with the invention;
[0013] FIG. 3 is a diagrammatic view showing two consecutive
sectors seen looking along III in FIG. 2;
[0014] FIG. 4 is a diagrammatic view of the casing associated with
such ring sectors;
[0015] FIG. 5 is a diagrammatic view showing the various possible
orientations for said first and second tongues; and
[0016] FIGS. 6 to 8 are fragmentary views showing variants of one
of the sectors shown in FIG. 3.
MORE DETAILED DESCRIPTION
[0017] In the drawings, and more particularly in FIGS. 2 to 4,
there can be seen turbine ring sectors 11 constituting the
stationary shroud of a rotor (not shown), specifically a rotor in
the high pressure turbine of a turbojet. This turbine is located
downstream from the combustion chamber. Specifically, such a ring
is made up of thirty-two curved ring sectors 11 such as those
shown, disposed end to end to form a slightly conical shroud
surrounding said rotor. Each sector 11 is constituted by a slightly
curved thick plate so as to build up the ring. There is a
substantially rectangular inside face 12 that is slightly concave
and that is referred to as the "hot" face since it comes into
contact with the stream of hot gas, and a substantially rectangular
outer face 14 referred to as the "cold" face. Relative to the flow
direction of hot gas passing through the rotor, there is also an
inlet edge 16 facing the combustion chamber nozzle, and an opposite
outlet edge 18. Each sector 11 also has two radial faces 20 and 21
via which it is connected circumferentially to the adjacent sectors
via sealing systems 26 (see FIG. 2) as mentioned above. Each
sealing system 26 is constituted by a set of tongues engaged in
corresponding slots defined in said facing radial faces 20, 21.
Each tongue is engaged in two slots belonging to two
circumferentially-adjacent ring sectors.
[0018] The tips of the rotor blades travel past the inner surface
of the ring as constituted in this way. The direction of rotation
is represented by arrow F in FIG. 3. The hot gas expelled from the
combustion chamber thus flows close to the inside surface of the
ring, which must therefore withstand very high temperatures. It is
therefore necessary both to minimize temperature gradient within
the structure of the ring as much as possible (thereby minimizing
in particular leakages of gas between the sectors), and also to
cool said ring effectively. For this purpose, use is made of a
fraction of the air delivered by the compressor feeding the
combustion chamber. To do this, each sector 11 is hollow and
includes a cooling air flow cavity 35 fed from the outside.
[0019] FIG. 4 is a highly diagrammatic view showing the position of
the ring made up from the set of sectors 11. A turbine casing 15
co-operates with the ring to define an annular cavity 17. The
assembly extends radially outside the high pressure bladed wheel
19, itself interposed axially between the high pressure nozzle 21
and the low pressure nozzle 23. Air coming from the compressor is
taken from a point upstream of the combustion chamber and
penetrates (via holes) into the annular cavity 17. This cavity thus
feeds all of the sectors in the ring. Each ring sector (FIG. 3) has
two distinct cavities 39 and 40 of zigzag shape, separated by a
partition 42, and fed via respective orifices 37 and 38. The air
flowing in the cavity 39 escapes via a series of ejection channels
44 opening out in the inlet side 16 of the ring sector, while the
air which flows in the cavity 40 escapes via a series of ejection
channels 44 opening out in the outlet side 18 of the ring
sector.
[0020] Apart from the sealing systems between the sectors, the
arrangement described above is already known. The invention relates
in particular to an advantageous improvement in said sealing
systems between the sectors.
[0021] More particularly (FIGS. 2 to 4), each sealing system 26 is
constituted in this case by three rectilinear tongues engaged in
respective rectilinear slots in the radial faces of two adjacent
sectors. Specifically, each sealing system (FIG. 2) comprises a
first tongue 27 and a second tongue 28 situated on the insides of
said radial faces, i.e. beside the hot faces of the sectors. The
tongues 27 and 28 are arranged in a chevron configuration, i.e.
they are engaged in slots 31 and 32 in said radial faces that
extend at an angle relative to the inner and outer faces 12 and 14
of the sectors. These slots define the relative positions of the
two tongues.
[0022] In addition, each sealing system includes a third tongue 29
extending substantially from one end to the other of the adjacent
sectors, parallel to the axis of the ring and on the outer side of
said radial faces. The tongue 29 is engaged in rectilinear slots 33
in the adjacent sectors. As can be seen in FIG. 2, the first tongue
27 extends between a point A situated close to the inlet side of
the two sectors close to the inside (i.e. close to the hot faces)
and a point B situated close to the third tongue 29. The second
tongue 28 is positioned so as to extend between a point C situated
close to the outlet side 18 of each of the sectors close to the
inside and a point D situated close to the first tongue,
substantially between the middle and a two-thirds point therealong
starting from point A.
[0023] The pressures which become established in the spaces between
the sectors on the inside and on the outside, and also between the
third tongue and said first and second tongues taken together are
such that said first and third tongues 27, 29 are pressed against
the inside faces of the slots 31, 33 in which they are received,
while said second tongue 28 is pressed against the outside faces of
the slots 32 in which it is received, as can be seen in FIG. 2.
[0024] The length of the first tongue 27 depends on the angle it
makes with the first tongue 29. Once this angle has been determined
(several possibilities are shown in FIG. 5), the position and the
length of the second tongue can be derived therefrom.
[0025] The angle defined between the first and third tongues may
lie in the range 15.degree. to 70.degree., approximately.
[0026] The slots can be machined accurately and they are well
located. The tongues can be inserted in these slots and their
relative positions can be well controlled. As a result the leakage
section between said first and second tongues (at S.sub.1) and the
leakage section between the first and third tongues (at S.sub.2)
are well controlled.
[0027] With reference more particularly to FIGS. 2 and 3, another
advantageous feature of the invention can be seen concerning the
cooling of the radial faces 20 and 21 with air from the cooling air
flow cavity 35. It can be seen that each sector has air ejection
channels 50 extending between the cavity 40 and at least one radial
face of the sector. These channels open out in the radial face 20
between its inside edge (hot face) and said first and second
tongues 27, 28. The chevron configuration of these two tongues
leaves room to form these air ejection channels. These channels are
disposed in a row parallel to the axis of the ring. In the example
of FIG. 3, they all extend perpendicularly to the radial face. In
the example of FIG. 6, some of the channels 50 extend
perpendicularly to the radial face while others situated at the
ends of said row, or at least one of them, are at an angle
diverging from the others, on going from the cavity towards the
radial face. The angle between the diverging channels may lie in
the range 10.degree. to 120.degree.. In certain circumstances,
channels could be provided at angles that converge in the opposite
direction. In the variant of FIG. 7, the channels are parallel and
form an angle relative to a direction perpendicular to the radial
face. The angle is such that the air is ejected with a component
directed towards the rear of the ring. In the variant of FIG. 8,
the channels are parallel and make an angle relative to a direction
perpendicular to the radial face. The angle is such that the air is
ejected with a component directed towards the front of the
ring.
[0028] In the example, the channels 50 open out it the radial face
20 that is the first face to be reached by the blades, given the
direction of rotation represented by arrow F. This is favorable for
avoiding or limiting any reintroduction of hot gas into the
inter-sector spaces. It would also be possible to make similar
channels through the opposite wall, opening out in the radial face
21. The air escaping from the channels 50 cools the wall through
which they are formed by convection (thermopumping), while the
opposite wall (face 21) is cooled by the impact of the jets of air.
In addition, the jets of air escaping from the channels 50 set up a
kind of fluidic system preventing hot gas being ingested.
[0029] It should also be observed that the slots 31, 32, and 33 are
preferably independent, i.e. they do not communicate with one
another. This avoids any need to make any tool clearance at the
junction between two slots. Leakage sections between the sectors
are also reduced.
[0030] The invention also provides any ring sector or any assembly
of ring sectors presenting the characteristics described above.
* * * * *