A LINEAR GASKET FOR AN INTER-BLADE PLATFORM
FIELD OF THE INVENTION
The invention relates to a linear gasket for an
5 inter-blade platform. Such a linear gasket is arranged
between a blade and a platform between blades and that is
distinct from the blades, and it serves to limit the flow
of air between the blade and the inter-blade platform.
Such a blade is used particularly, but not exclusively,
10 in fans, between the blades of the fan and the interblade
platforms.
PRIOR ART
An inter-blade platform linear gasket is known that
15 presents a length, the gasket comprising a linear base
for fastening to the inter-blade platform and a linear
lip projecting from the linear base, said linear lip
presenting a linear distal end portion configured to
contact a pressure side wall or a suction side wall of a
20 blade, a linear groove being formed between the linear
base and the linear lip over at least a fraction of the
length of said linear gasket. That type of gasket
extends along the pressure side or the suction side of a
blade, including its leading edge and/or trailing edge.
25 The lip of that type of prior art gasket does not
make it possible to fit closely to the blade in zones of
sudden discontinuity or of small radius of curvature,
such as for example in the vicinity of the leading edge
or the trailing edge of the blade. As a result, air
30 flows between the blade and the inter-blade platform in
those zones. The sealing of the air (or gas) passage is
thus not perfect, thereby degrading the performance of
the gas turbine reaction engine.
35 SUMMARY OF THE INVENTION
The object of the present invention is to remedy the
above-mentioned drawback, at least substantially.
The invention achieves this object by proposing a
linear gasket of the above-specified type, wherein at
least one linear slit extending over at least a fraction
of the length of said gasket.
5 Below, the terms "gasket", "base", "lip", "groove",
"slit", and "distal end portion" may be used instead of
"linear gasket", "linear base", "linear lip", "linear
groove", "linear slit", and "linear distal end portion",
in order to designate the same entities. Likewise, the
10 term "platform" may be used instead of "inter-blade
platform" to designate the same entity.
It can be understood that the linear gasket extends
in a preferred direction, the longitudinal direction.
This longitudinal direction is not necessarily
15 rectilinear, and is preferably configured to follow the
outlines of the blade, in particular in the vicinity of
discontinuities of the blade. In other words, it can be
considered that the length direction follows the neutral
axis of the gasket. The length of the gasket is thus
20 defined and measured parallel to this longitudinal
direction. Likewise, the linear lip, the linear base,
and the linear groove all extend along this longitudinal
direction. The length of the lip, the length of the
base, and the length of the groove are defined and
25 measured likewise parallel to this longitudinal
direction. It can be understood that the lip projects
widthwise in a direction that is transverse relative to
the longitudinal direction from the base. The groove is
defined between the base and the lip in the portions of
30 the gasket where the base and the lip form an angle of
less than 90" (ninety degrees of angle), the angle being
measured in a cross-section relative to the longitudinal
direction. The linear distal end portion is a portion
that extends lengthwise in the longitudinal direction,
35 and widthwise over a distance of about 20% of the width
of the lip. It can thus be understood that the linear
distal end portion is arranged remote from the junction
zone between the lip and the base. At least one linear
slit is arranged in the linear distal end portion and
extends in the longitudinal direction.
Because of the linear slit, the distal end portion
5 is locally more flexible than the same distal end portion
would be if it did not have such a slit. In comparison
with gaskets of the prior art, the slit thus enables the
lip to fit more closely to the outline of the blade, in
particular in zones of the blade having a sudden
10 discontinuity or a small radius of curvature.
Furthermore, since the gasket is locally more flexible
because of the slit, it adapts to the shape of the blade
while being subjected to smaller mechanical stresses and
wear than those to which prior art gaskets are subjected,
15 thereby improving the lifetime of the gasket of the
invention compared with prior art gaskets.
Preferably, the at least one linear slit is formed
in a lip segment configured to contact the blade in the
vicinity of a leading edge of the blade and/or in the
20 vicinity of a trailing edge of the blade.
It can be understood that a lip segment is a portion
of the lip considered in the longitudinal direction. The
leading edge and the trailing edge of a blade are the
regions that present the most sudden discontinuities. By
25 placing a slit in the lip segments that are configured to
come into contact with the blade in the vicinity of the
leading edge and of the trailing edge, it is ensured that
the gasket will fit as closely as possible to the wall of
the blade, including in the vicinity of the leading edge
30 and of the trailing edge.
Advantageously, the linear slit extends over the
entire length of the linear lip.
In this configuration, it is ensured that the distal
end portion presents local flexibility enabling the lip
35 to match the shape of the contact surface of the blade
all along its length. This provides the gasket with
better ability to achieve leaktight contact with the wall
of the blade.
Advantageously, the inter-blade linear gasket
presents a cross-section that varies along the length of
5 the gasket.
It can be understood that the shape of the crosssection
of the linear gasket (i.e. its section on a plane
perpendicular to the longitudinal direction of the
gasket) varies in the longitudinal direction of the
10 gasket. By having such a varying section, the gasket is
adapted to fit as closely as possible to the blade
depending on the shape of the blade.
In an embodiment, the cross-section of the platform
varies and/or the cross-section of the lip varies.
15 Advantageously, the base presents a shoulder
configured to co-operate with an edge of the inter-blade
platform.
The linear gasket is generally arranged along an
edge of a platform, said edge being for facing the
20 pressure side or the suction side of the blade. Such a
shoulder enables the gasket to be properly positioned
relative to the platform while the gasket is being
assembled on the platform. By means of such a shoulder,
the gasket thus presents a protective portion covering
25 said edge of the platform. Such a protective portion
serves in particular to damp any impacts between the
blade and the platform (or between facing portions of two
adjacent platforms), should they come into contact.
Advantageously, inter-blade linear gasket includes
30 at least one lip stiffener.
Such a stiffener serves to make the entire lip
stiffer over a segment of the lip, the lip thus being
pressed better against the wall of the blade. Thus, by
means of the stiffener, the lip is pressed against the
35 wall of the blade, whereas by means of the slit, the
distal end of the lip is a close fit to the shape of the
wall of the blade and provides leaktight contact.
The invention also provides an inter-blade platform
including an inter-blade platform linear gasket of the
invention.
The invention also provides a rotor comprising a
5 disk having, mounted at its periphery, a plurality of
blades and a plurality of inter-blade platforms, an
inter-blade platform being arranged between each pair of
adjacent blades, at least one of the inter-blade
platforms including at least one inter-blade platform
10 linear gasket of the invention.
Advantageously, the lip of said linear gasket is
configured to co-operate with a blade root under a
leading edge of said blade, in the vicinity of said
leading edge.
15 In a height direction, a blade presents, in
succession, a root followed by an airfoil, the root being
the portion whereby the blade is fastened to the disk.
The airfoil is the portion of the blade that interacts
with air, this airfoil having a leading edge, a trailing
20 edge, a pressure side, and a suction side. The root
presents an intermediate portion that does not engage the
disk. It can be understood that the gasket co-operates
with the blade in this intermediate portion. The term
"beneath" relates to the height direction of the blade,
25 the blade root defining the bottom of the blade and the
airfoil defining the top of the blade. Thus, by stating
that the gasket is placed beneath the leading edge, it
should be understood that the gasket is placed in the
height direction towards the bottom of the blade relative
30 to the transition zone between the root and the airfoil
of the blade, in register with the leading edge. The
term "in the vicinity" means that the gasket is arranged
in the height direction in a zone extending over about
10% of the total height of the blade beneath the leading
35 edge, and in the longitudinal direction in a zone
centered on the leading edge and extending over about 20%
of the length of the blade.
Advantageously, each of at least two inter-blade
platforms has at least one inter-blade platform linear
gasket of the invention, the at least two inter-blade
platforms being adjacent to a common blade, said at least
5 one linear gasket of an inter-blade platform from the at
least two inter-blade platforms being arranged facing
said at least one linear gasket of the other inter-blade
platform from the at least two inter-blade platforms
upstream from a leading edge and/or downstream from a
10 trailing edge of each blade, said linear gaskets cooperating
by pressing against each other upstream from
the leading edge and/or downstream from the trailing edge
of said blade.
The terms "upstream" and "downstream" refer to the
15 flow direction of air (or gas) along the blade, the air
flowing generally from the leading edge towards the
trailing edge. It can be understood that each of two
adjacent platforms on either side ef a blade has a
respective gasket of the invention on its edge facing
20 said blade. These gaskets extend beyond the leading edge
and beyond the trailing edge of the blade (i.e. the
gaskets are longer than the blade), and they co-operate
directly with each other by pressing against each other
in these zones beyond the leading and trailing edges.
25 The invention also provides a gas turbine reaction
engine including a rotor of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention and its advantages can better
30 understood on reading the following detailed description
of embodiments of the invention given as non-limiting
examples. The description refers to the accompanying
drawing sheets, in which:
Figure 1 shows a gas turbine reaction engine of
35 the invention;
Figure 2 is a fragmentary view of a section of the
fan of the Figure 1 gas turbine reaction engine;
Figure 3 is a fragmentary view in perspective of
the gasket of the invention within the fan of the gas
turbine reaction engine of the invention;
Figure 4 shows the Figure 2 fan seen looking along
arrow IV;
Figure 5 shows the linear gaskets of Figure 4 on
section V;
Figure 6 shows the linear gaskets of Figure 4 on
section VI;
Figure 7 shows the linear gaskets of Figure 4 on
section VII;
Figure 8 shows the linear gaskets of Figure 4 on
section VIII;
Figure 9 shows the linear gaskets of Figure 4 on
section IX; and
Figure 10 shows a segment of the linear gasket of
the invention in a perspective view.
DETAILED DESCRIPTION OF EMBODIMENTS
Figure 1 shows a gas turbine reaction engine 100
including fan 80 forming a rotor of the invention. As
shown in Figure.2, the fan 80 comprises a disk 82 having
mounted at its periphery both a plurality of blades 50
and a plurality of inter-blade platforms 40, each blade
50 being interposed between two inter-blade platforms 40.
In other words, each platform 40 is arranged between a
pair of adjacent blades 50. In this example, each edge
42a and 42b of each platform 40, facing the pressure side
52a and the suction side 52b of respective blades 50, is
provided with a respective linear gasket 10 or 10' of the
invention. Each linear gasket 10 and 10' presents a
respective linear base 12, 12' and a linear lip 14, 14',
a respective linear groove 16, 16' being formed between
the base 12 and the lip 14 or between the base 12' and
the lip 14'. In this example, the gasket 10 is
configured to co-operate with the blade 50 on its
pressure side 52a, while the gasket 10' is configured to
co-operate with the blade 50 on its suction side 52b.
Each blade 50 presents in succession along its height H,
a root 51 followed by an airfoil 52. The root 51
presents a portion 51a engaged in the disk 82 and an
5 intermediate portion 51b. The airfoil 52 presents the
pressure side 52a, the suction side 52b, a leading edge
52c, and a trailing edge 52d (cf. Figure 4).
In general, the pressure side wall and the suction
side wall are substantially continuous (i.e. they do not
10 show any significant differences) between the
intermediate portion 51b of the root 51 and the airfoil
52, such that the pressure side wall and the suction side
wall of the blade at the root of the blade are sometimes
also referred to as the pressure side and the suction
15 side.
As shown in Figure 3, the lip 14 of the gasket 10
co-operates with the root 51 of the blade 50 beneath the
leading edge 52c of the blade 50 in the vicinity of said
leading edge 52c. Although not shown, the gasket 10' co-
20 operates likewise with the root 51 of the blade 50,
beneath the leading edge ,52c of the blade 50, in the
vicinity of said leading edge 52c. It should be observed
that Figure 3 is a fragmentary view that shows only a
portion of the blade 50 (a portion of the intermediate
25 portion 51a and a portion of the airfoil 52), together
with a portion of the platform 40 and a portion of the
gasket 10.
Figure 4 is a view of a blade 50 together with two
platforms 40 seen looking along arrow IV of Figure 2.
30 The gaskets 10 and 10' extend from upstream of the
leading edge 52c of the blade 50 to downstream of the
trailing edge 52d of the blade 50. Thus, each gasket 10
and 10' presents a segment 10a, 10'a that extends
upstream from the leading edge 52c, a segment lob, 10'b
35 that extends facing the pressure side 52a or the suction
side 52b respectively of the blade 50, and a segment 10c,
10'c that extends downstream from the trailing edge 52d
of the blade 50. "Upstream" and "downstream" are
considered relative to the flow of air as represented by
arrow C flowing along the blade 50, with the arrow C
pointing from upstream to downstream. Each gasket
5 segment extends over a longitudinal portion of the
gasket. The longitudinal directions of the gaskets 10
and 10' are represented by respective dashed lines L and
L'. The upstream segments 10a and 10'a face each other
such that the lips 14 and 14' of the gaskets 10 and 10'
10 co-operate by bearing against each other in the zone
upstream from the blade 50 (cf. Figure 5). Likewise, the
downstream segments 10c and 10'c face each other so that
the lips 14 and 14'c of the gaskets 10 and 10' co-operate
by pressing against each other in the zone downstream
15 from the blade 50 (cf. Figure 9).
In the zones that are configured to come into
contact with the vicinity of the leading edge 52c and of
the trailing edge 52d, the gaskets 10 and 10' present
linear slits 120 & 122 and 120' & 122' (cf. Figures 5, 6,
20 8, and 9). These slits 120, 122 and 120', 122' extend
respectively along directions that are substantially
parallel to the longitudinal directions L and L'. It
should be observed that along the outline of the blade
50, the longitudinal directions L and L' are
25 substantially parallel to the walls of the blade 50.
As shown in Figures 5 and 6, the linear distal end
portions 14a and 14'a have respective linear slits 120
and 120'. Each of these Figures 5 and 6 shows a section
of the assembly comprising a blade and platforms as shown
30 in Figure 4 in the vicinity of the leading edge 52c of
the blade 50. Directions B and B' that are respectively
substantially parallel to the lips 14 and 14', indicate
the respective width directions of the lips 14 and 14'.
The "distal" nature of the distal end portion is
35 considered along these directions B and B', the distal
end portion of a lip being remote from its base along the
width direction of the lip. Figure 7 is a section
through the assembly of a blade and platforms as shown in
Figure 4 in a zone that is distinct from being in the
vicinity of the leading edge 52c or of the trailing edge
52d of the blade 50. In this zone that is distinct from
5 the vicinity of the leading edge 52c and of the trailing
edge 52d, the gaskets 10 and 10' do not present any
linear slit. In the same manner as in the vicinity of
the leading edge 52c, the gaskets 10 and 10' present
respective slits 122 and 122' in the vicinity of the
10 trailing edge 52d in the distal end portion 14a of the
lip 14 and in the distal end portion 14'a of the lip 14',
as shown in Figures 8 and 9.
The cross-section of the gaskets 10 and lo', and
more particularly of the base 12 and of the lip 14 of the
15 gasket 10 and of the base 12' and of the lip 14' of the
gasket lo', varies along the longitudinal direction L or
L ' , as can be seen in Figures 5 to 9.
Figure 10 shows a segment of gasket 10 including
stiffeners 18. In this example, each stiffener 18 is in
20 the form of a rib formed integrally with the gasket 10.
In a variant, a stiffener is formed by reinforcement
arranged in the thickness of the lip, or indeed by a
sheath arranged around the lip. Such stiffeners may also
be provided for the gasket 10'.
2 5 The gaskets 10 and 10' present respective shoulders
20 and 20' arranged in the thickness of the base 12 or
12'. Thus, each of the bases 12 and 12' presents a
protective portion 12a or 12'a respectively covering the
edge 42a or 42b of a platform 40. As shown in Figures 4
30 to 9, the protective portions 12a and 12'a are thicker in
the segments 10a, 10'a and 10c, 10'c (i.e. upstream from
the leading edge and downstream from the trailing edge)
than in the segments lob and 10'b. These greater
thicknesses in these zones serve in particular to stiffen
35 the gaskets 10 and 10' in the zones and prevent the lips
from folding outwards (i.e. occupying positions beside
the airfoil 52 of the blade).
The gaskets 10 and 10' are preferably made of
plastic elastomer and they are fabricated by molding.
Although the present invention is described with
reference to specific embodiments, it is clear that
5 modifications and changes may be made to those
embodiments without going beyond the general ambit of the
invention as defined by the claims. In particular,
individual characteristics of the various embodiments
shown and/or mentioned may be combined in additional
10 embodiments. Consequently, the description and the
drawings could be considered in an illustrative sense
rather than a restricted sense.

CLAIMS
1. A linear gasket (10; 10') for an inter-blade platform
that presents a length, the gasket comprising a linear
base (12; 12') for fastening to the inter-blade platform
5 (40) and a linear lip (14; 14') projecting from the
linear base (12; 12'), said linear lip (14; 14')
presenting a linear distal end portion (14a) configured
to contact a pressure side wall (52a) or a suction side
wall (52d) of a blade (50), a linear groove (16; 16')
10 being formed between the linear base 1 2 1 and the
linear lip (14; 14') over at least a fraction of the
length of said linear gasket (10; lo'), the gasket being
characterized in that the linear distal end portion (14a;
14'a) presents at least one linear slit (120, 122; 1201,
15 122') extending over at I east a fraction of the length of
said gasket (10; 10').
2. An inter-blade platform linear gasket (10; 10')
according to claim 1, wherein the at least one linear
20 slit (120, 122; 120'; 122') is formed in a lip segment
(lOa, 10c; 1O1a, 10'c) configured to contact the blade
(50) in the vicinity of a leading edge (52a) of the blade
and/or in the vicinity of a trailing edge (52d) of the
blade.
2 5
3. An inter-blade platform linear gasket (10; 10')
according to claim 1 or claim 2, wherein the linear slit
(120, 122; 120', 122') extends over the entire length of
the linear lip (14; 14').
30
4. An inter-blade platform linear gasket (10; 10')
according to any one of claims 1 to 3, presenting a
cross-section that varies along the length of the gasket
(10, 10').
35
5. An inter-blade platform linear gasket (10; 10')
according to any one of claims 1 to 4, including at least
one stiffener (18) of the lip (14).
5 6. An inter-blade platform (40) including an inter-blade
platform linear gasket (10; 10') according to any one of
claims 1 to 5.
7. A rotor (80) comprising a disk (82) having, mounted at
10 its periphery, a plurality of blades (50) and a plurality
of inter-blade platforms (40), an inter-blade platform
(40) being arranged between each pair of adjacent blades
(50), at least one of the inter-blade platforms (40)
including at least one inter-blade platform linear gasket
15 (10; 10') according to any one of claims 1 to 5.
8. A rotor (80) according to claim 7, wherein the lip of
said linear gasket (10; 10') is configured to co-operate
with a blade root (51) under a leading edge (52c) of said
20 blade (50), in the vicinity of said leading edge (52c) .
9. A rotor (80) according to claim 7 or claim 8,
including at least two inter-blade platforms (40), each
having at least one inter-blade platform linear gasket
25 (10; 10') according to any one of claims 1 to 5, the at
least two inter-blade platforms (40) being adjacent to a
common blade (50), said at least one linear gasket (10)
of an inter-blade platform (40) from the at least two
inter-blade platforms (40) being arranged facing said at
30 least one linear gasket (10') of the other inter-blade
platform (40) from the at least two inter-blade platforms
(40) upstream from a leading edge (52c) and/or downstream
from a trailing edge (52d) of each blade (50), said
linear gaskets (10; 10') co-operating by pressing against
35 each other upstream from the leading edge (52c) and/or
downstream from the trailing edge (52d) of said blade
(50).
10. A gas turbine reaction engine (100) including a rotor (80) according to any one of claims 7 to 9.