JOINTURE DE BOUCLE POUR UN CARENAGE DIVISE D'UN MOTEUR A TURBINE A GAZ

BUCKLE JOINT FOR SPLIT FAIRING OF A GAS TURBINE ENGINE

Abrégé français

La présente invention se rapporte à un carénage de support de moteur à turbine à gaz (10, 110) qui comprend : des bandes interne et externe ; une aube de forme profilée (12, 112) qui s'étend entre les bandes ; le carénage (10, 110) est divisé le long d'un plan transversal qui passe à travers les bandes et l'aube (12, 112), ce qui définit une pièce de nez (24, 124) et une pièce de queue (26, 126) ; l'aube (12, 112) étant définie par des parois latérales espacées (18) qui s'étendent entre un bord d'attaque et un bord de fuite, chaque paroi latérale (18) étant divisée en parties avant et arrière par le plan transversal ; chaque partie de paroi latérale supportant un montant s'étendant radialement vers l'intérieur (32, 34, 132, 134), comportant une face de contact (40, 46, 140, 146), les montants (32, 34, 132, 134) étant positionnés avec leurs faces de contact respectives (40, 46, 140, 146) qui viennent en contact les unes avec les autres ; et une paire de boucles inclinées (38, 138), chaque boucle (38, 138) entourant et fixant ensemble une paire de montants (32, 34, 132, 134) ; un élément mécanique (76, 143) venant en prise avec les faces de contact (40, 46, 140, 146) des montants appariés (32, 34, 132, 134) de sorte à bloquer un mouvement radial relatif des montants appariés (32, 34, 132, 134).

Abrégé anglais

A gas turbine engine strut fairing (10, 110) includes: inner and outer bands; a hollow, airfoil-shaped vane (12, 112) extending between the bands; wherein the fairing (10, 110) is split along a transverse plane passing through the bands and vane (12, 112), defining a nose piece (24, 124) and a tail piece (26, 126); wherein the vane (12, 112) is defined by a spaced-apart sidewalls (18) extending between a leading edge and a trailing edge, each the sidewalls (18) being split into forward and aft portions by the transverse plane; wherein each of the sidewall portions carries a radially-inwardly extending post (32, 34, 132, 134), having a mating face (40, 46, 140, 146), the posts (32, 34, 132, 134) positioned with pairs of the posts (32, 34, 132, 134) lie adjacent to each other, with their respective mating faces (40, 46, 140, 146) contacting each other; and a pair of slotted buckles (38, 138), each buckle (38, 138) surrounding and clamping together a pair of the posts (32, 34, 132, 134); wherein a mechanical element (76, 143) engages the mating faces (40, 46, 140, 146) of the paired posts (32, 34, 132, 134), so as to block relative radial movement of the paired posts (32, 34, 132, 134).

Revendications

WHAT IS CLAIMED IS.
1. A fairing (10, 110) for a strut in a gas turbine engine, comprising:
an inner band (16, 116);
an outer band (14, 114);
a hollow, airfoil-shaped vane (12, 112) extending between the inner and
outer bands;
wherein the fairing (10, 110) is split along a generally transverse plane
passing through the inner band (16, 116), outer band (14, 114) and vane (12,
112) to
define a nose piece (24, 124) and a tail piece (26, 126),
wherein the vane (12, 112) is defined by a pair of spaced-apart sidewalls (18)
extending between a leading edge and a trailing edge, each of the sidewalls
(18) being
split into forward and aft portions by the transverse plane;
wherein each of the sidewall portions carries a radially-inwardly extending
post (32, 34, 132, 134), each post (32, 34, 132, 134) including a mating face
(40, 46,
140, 146), the posts (32, 34, 132, 134) positioned such that pairs of the
posts (32, 34,
132, 134) lie adjacent to each other, with their respective mating laces (40,
46, 140,
146) contacting each other; and
a pair of slotted buckles (38, 138), wherein each slotted buckle (38, 138)
surrounds and clamps together a pair of the posts (32, 34, 132, 134);
wherein a mechanical element (76, 143) engages the mating faces (40, 46,
140, 146) of the paired posts (32, 34, 132, 134) to block relative radial
movement of
the paired posts (32, 34, 132, 134), and wherein each pair of the adjacent
posts (32, 34,
132, 134) contacts a slot of the corresponding buckle (38, 138) in a tripod
contact
configuration.
2. The fairing (10, 110) of claim 1 wherein:
each of the mating faces (40, 46, 140, 146) has a transverse groove (41, 43)
formed therein, and
a shear member passes laterally through each buckle (38, 138) and engages
the transverse grooves (41, 43) in the mating faces (40, 46, 140, 146) of the
paired posts
(32, 34, 132, 134), so as to block relative radial movement of the paired
posts (32, 34,
132, 134).
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3. The fairing (10, 110) of claim 2 wherein the shear member is a
circular cross-section pin (76).
4. The fairing (10, 110) of claim 1 wherein each of the mating faces (40,
46, 140, 146) includes at least one alignment element (143) that is protruding
or
recessed in the axial direction relative to the remainder of the otherwise
planar mating
face (40, 46, 140, 146), the posts (32, 34, 132, 134) positioned such that
pairs of the
posts (32, 34, 132, 134) lie adjacent to each other, with their respective
mating faces
(40, 46, 140, 146) contacting each other such that the respective alignment
elements
(143) engage each other.
5: The fairing (10, 110) of claim 4 wherein the alignment feature is
an
S-shaped profile
6. The fairing (10, 110) of claim 4 wherein there is a nonzero angle
between a long axis of the alignment element (143) and a radial direction,
defining an
interference condition which prevents relative radial movement.
7. The fairing (10, 110) of claim 1 wherein:
each pair of adjacent posts (32, 34, 132, 134) includes at least two non-
parallel faces.
8. The fairing (10, 110) of claim 1 wherein the post (34, 134) of each
sidewall portion of the tail piece (26, 126) includes a mating face (46, 146)
and a pair
of flank faces (48) opposite the mating face (46, 146), the flank faces (48)
oriented to
form a "V" shape.
9. The fairing (10, 110) of claim 1 wherein the post (32, 132,) of each
sidewall portion of the nose piece (24, 124) includes a mating face (40, 140),
a pressure
face (42) opposite the mating face (40, 46, 140, 146), and a pair of spaced-
apart side
faces (44) flanking the pressure face (42), wherein the pressure face (42) is
disposed at
an acute angle to the transverse plane.
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10. The fairing (10, 110) of claim 9 wherein the slot (62, 162) is
sized
and shaped such that there will be substantially no contact between the side
faces (44)
of the post (32, 132), and the slot (62, 162) when assembled
11 The fairing (10, 110) of claim 1 wherein:
the buckle (38, 138) is a monolithic structure with forward and aft ends,
inner
and outer surfaces, and side surfaces;
a slot (62, 162) is formed in the buckle (38, 138) extending from the inner
surface to the outer surface, the slot (62, 162) including a forward wall
adjacent the
forward end, and a pair of flanking walls adjacent the aft end;
the flanking walls are oriented to form a "V" shape; and
in conjunction with the forward wall, the flanking walls form a generally
triangular shape in plan view from the outer surface.
12. The fairing (10, 110) of claim 11 wherein:
the forward wall of the buckle (38, 138) is generally planar and is inclined
at
an acute angle to the outer surface, so as to lie generally parallel to the
pressure face of
the post (32, 34, 132, 134) when installed; and
each of the flanking walls of the buckle (38, 138) is generally planar, and
the
flanking walls are oriented so as to lie generally parallel to the flank faces
of the post
(32, 34, 132, 134) when installed.
13. The fairing (10, 110) of claim 1 wherein a pin (70) passes through the
buckle (38, 138) and at least one of the posts (32, 34, 132, 134).
14. The fairing (10, 110) of claim 1 wherein mating surfaces of the
sidewalls (18) have a non-planar shape.
15. The fairing (10, 110) of claim 1 wherein the slotted buckles (38, 138)
are secured to the posts (32, 34, 132, 134) of the tail piece (26, 126) by
brazing.
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Description

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BUCKLE JOINT FOR SPLIT FAIRING OF A GAS TURBINE ENGINE
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to gas turbine engine turbines and
more
particularly to fairings for stationary structural members of such engines.
[0002] Gas turbine engines frequently include a stationary turbine frame, also
referred to
as an inter-turbine frame or turbine center frame ("TCF"), which provides a
structural
load path from bearings which support the rotating shafts of the engine to an
outer
casing, which forms a backbone structure of the engine. Turbine frames
commonly
include an annular, centrally-located hub surrounded by an annular outer ring,
which are
interconnected by a plurality of radially-extending struts. The turbine frame
crosses the
combustion gas flowpath of the turbine and is thus exposed to high
temperatures in
operation. Such frames are often referred to as "hot frames", in contrast to
other structural
members which are not exposed to the combustion gas flowpath.
[0003] To protect them from high temperatures, turbine frames are typically
lined with
high temperature resistant materials that isolate the frame structure from hot
flow path
gasses. The liner must provide total flow path coverage including the frame
outer ring or
case, hub structure, and struts.
[0004] One known configuration to protect the struts is an interlocking split
fairing
arrangement in which forward and aft sections of individual fairing/nozzle
components
are sandwiched around the struts. This arrangement uses a tab-and-buckle (or
post-and-
buckle) coupling assembly having a buckle with a rectangular opening that
receives
generally rectangular tabs to keep the fairing halves together after assembly
to the frame.
An example of this tab-and-buckle arrangement is described in U.S. Patent
8,152,451 to
Manteiga et al.
[0005] While effective to secure the fairing halves together, the prior art
rectangular
post/buckle configuration, however, requires tight tolerance match machining
of the post
and buckle to ensure alignment and fit of the members and relies on clearance
gaps in the
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buckle joint to accommodate assembly. This can lead to gaps at assembly and in
operation, creating potential "forward facing steps" or "aft facing steps" and
air leakage
into the flowpath.
[0006] Accordingly, there is a need for a post-and-buckle joint for a turbine
strut fairing
which is positively locked to avoid flowpath steps.
BRIEF SUMMARY OF THE INVENTION
[0007] This need is addressed by the present invention, which provides a split
fairing
assembly for a turbine frame incorporating a post-and-buckle coupling
arrangement with
a shear member to prevent misalignment.
[0008] According to one aspect of the invention, a fairing for a strut in a
gas turbine
engine includes: an inner band; an outer band; a hollow, airfoil-shaped vane
extending
between the inner and outer bands; wherein the fairing is split along a
generally
transverse plane passing through the inner band, outer band and vane, so as to
define a
nose piece and a tail piece; wherein the vane is defined by a pair of spaced-
apart
sidewalls extending between a leading edge and a trailing edge, each of the
sidewalls
being split into forward and aft portions by the transverse plane; wherein
each of the
sidewall portions carries a radially-inwardly extending post, each post
including a
mating face, the posts positioned such that pairs of the posts lie adjacent to
each other,
with their respective mating faces contacting each other; and a pair of
slotted buckles,
wherein each slotted buckle surrounds and clamps together a pair of the posts;
wherein a
mechanical element engages the mating faces of the paired posts, so as to
block relative
radial movement of the paired posts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention may be best understood by reference to the following
description
taken in conjunction with the accompanying drawing figures in which:
[0010] FIG. 1 is a perspective view of a strut fairing constructed according
to an aspect
of the present invention;
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[0011] FIG. 2 is an exploded perspective view of the strut fairing of FIG. 1;
[0012] FIG. 3 is a schematic plan view of a portion of the buckle and posts of
the strut
fairing of FIG. 1;
[0013] FIG. 4 is a partially-cut-away side view of the buckle and post of FIG.
3;
[0014] FIG. 5 is a perspective view of an alternative strut fairing
constructed according
to an aspect of the present invention;
[0015] FIG. 6 is an exploded perspective view of the strut fairing of FIG. 5;
[0016] FIG. 7 is a schematic plan view of a portion of the buckle and posts of
the strut
fairing of FIG. 6; and
[0017] FIG. 8 is a rear elevation view of a portion of a post of the strut
fairing of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Referring to the drawings wherein identical reference numerals denote
the same
elements throughout the various views, FIG. 1 depicts a strut fairing 10
suitable for use in
a gas turbine engine, for example to surround and protect a structural strut
or a service
tube of a structural frame. The strut fairing 10 includes an airfoil-shaped
vane 12 that is
supported between an arcuate outer band 14 and an arcuate inner band 16. The
inner and
outer bands 16 and 14 are axially elongated and shaped so that they define a
portion of
the flowpath through the turbine frame.
[0019] The vane 12 is axially elongated and includes spaced-apart sidewalls 18
extending between a leading edge 20 and a trailing edge 22. The sidewalls 18
are shaped
so as to form an aerodynamic fairing for the a gas turbine engine frame strut
or other
similar structure of a known type (not shown) The components of the strut
fairing 10,
including the inner band 16, outer band 14, and vane 12 are split, generally
along a
common transverse plane, so that the strut fairing 10 has a nose piece 24 and
a tail piece
26 (see FIG. 2). Each of the sidewalls 18 is divided into forward and aft
portions.
[0020] The nose pieces 24 and tail pieces 26 are cast from a metal alloy
suitable for high-
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temperature operation, such as a cobalt- or nickel-based "superalloy", and may
be cast
with a specific crystal structure, such as directionally-solidified (DS) or
single-crystal
(SX), in a known manner. An example of one suitable material is a nickel-based
alloy
commercially known as RENE N4.
[0021] The interior lateral spacing between the sidewalls 18 is selected such
that the nose
piece 24 can slide axially over the strut or other structure from forward to
aft, and the tail
piece 26 can slide axially over the strut or other structure from aft to
forward. This
permits installation or removal of the nose piece 24 or tail piece 26 without
disassembly
of the turbine frame or removal of the strut. The inner lateral interior
surfaces of the
sidewalls 18 are substantially free of any protuberances, hooks, bosses, or
other features
that would interfere with the free axial sliding.
[0022] Optionally, the mating faces 28 and 30 of the nose piece 24 and the
tail piece 26
may have a shape that is at least partially non-planar as a means of blocking
leakage of
cooling air or ingestion of hot flowpath gases.
[0023] Means are provided for securing the nose piece and the tail piece 24
and 26 to
each other. In the illustrated example, the nose piece 24 includes posts 32
which extend
in a generally radially inward direction adjacent its aft face 28, and the
tail piece 26
includes posts 34 which extend in a generally radially inward directly
adjacent its
forward face 30. When assembled, the posts 32 and 34 are received in a slot 36
of a
metallic buckle 38. (It is noted that to permit assembly, the posts 32 and 34
may be
oriented in a direction that is not strictly radial to the engine centerline,
but rather
perpendicular to a waterline cut through the engine; that is, the posts 32 and
34 would be
generally parallel to each other).
[0024] The posts 32 and 34 and the buckle 38 may be collectively configured to
define a
"tripod" contact configuration which is self-aligning and which does not
require precise
match-machining of the component parts.
[0025] Each of the posts 32 includes a mating face 40 facing the nose
piece/tail piece
split line, a pressure face 42 opposite the mating face 40, and a pair of
spaced-apart side
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faces 44. The pressure face 42 is disposed at an acute angle "A" to an engine
radial
direction "R" (which is also parallel to the nosepiece/tailpiece split line).
The mating face
40 includes a transverse groove 41 formed therein (in the illustrated example
the groove
has a semicircular cross-sectional shape). The axis of the groove 41 extends
parallel to a
waterline cut through the engine. The groove 41 is formed during a drilling
operation
which is described in more detail below.
[0026] Each of the posts 34 includes a mating face 46 facing the nose
piece/tail piece
split line, and a pair of spaced-apart side flank faces 48. The flank faces 48
are oriented
to form a "V" shape, and in conjunction with the mating face 46 they form a
generally
triangular shape in plan view. The flank faces 48 extend generally parallel to
the radial
direction "R". The mating face 46 includes a transverse groove 43 formed
therein (in the
illustrated example the groove has a semicircular cross-sectional shape). The
axis of the
groove 43 extends parallel to a waterline cut through the engine. The groove
43 is formed
during a drilling operation which is described in more detail below.
[0027] The buckle 38 is a monolithic structure with a forward and aft ends 50
and 52,
inner and outer surfaces 54 and 56, and side surfaces 58 and 60. A slot 62 is
formed in
the buckle 38 extending from the inner surface 54 to the outer surface 56. The
slot 62
includes a forward wall 64 adjacent the forward end 50, and a pair of flanking
walls 66
adjacent the aft end 52. The forward wall 64 is generally planar and is
inclined at an
acute angle to the outer surface 56. The forward wall 64 is angled to as to
lie generally
parallel to the pressure face 42 of the post 32 when installed. Each of the
flanking walls
66 is generally planar. The flanking walls 66 are oriented so as to lie
generally parallel to
the flank faces 48 of the post 34 when installed. The flanking walls 66 are
oriented to
form a "V" shape, and in conjunction with the forward wall 64 they form a
generally
triangular shape in plan view from the outer surface 56. Transition walls 68
may
interconnect the flanking walls 66 and the forward wall 64. The slot 62 is
sized and
shaped such that there will be essentially no contact between the side faces
44 of the post
32 and the slot 62 when assembled.
[0028] Referring to FIG. 3, When the nose piece 24 and the tail piece 26 are
assembled
to each other, the mating face 40 of each post 32 contacts the mating face 46
of the
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corresponding post 34. The slot 62 of the buckle 38 receives the posts 32 and
34. The
flanking walls 66 of the slot 62 bear against the corresponding flaffl( faces
48 of the post
34, and the forward wall 64 of the slot 62 bears against the pressure face 42
of the post
32. As the buckle 38 is moved in a generally radial direction towards the nose
piece 24
and tailpiece 26, interaction of the pressure face 42 forces the buckle 38
against the flank
faces 48, removing substantially all of the clearance between the two posts 32
and 34,
and between the buckle 38 and the posts 32 and 34. To the extent that the
posts 32 and 34
and the slot 62 do not match their nominally-specified dimensions, the buckle
38 is
simply forced on to the posts 32 and 34 to a greater or lesser degree.
[0029] Once the buckle 38 has been dry-fitted and all assembly clearance
removed, the
buckle 38 is temporarily secured to the post 34. For example, the buckle 38
could be
tack-welded to the post 34. Alternatively, holes can be line-drilled through
the buckle 38
and the post 34, and a press-fit buckle pin 70 installed. The nose piece 24
can then be
removed, and the buckle 38 is rigidly secured to the post 34, for example by a
known
brazing process.
[0030] Once the buckle 38 has been secured to the post 34, the nose piece 24
and the tail
piece 26 are reassembled. The forward portion of the buckle 38 and the split
line between
the posts 32 and 34 are then line-drilled, resulting in holes 72 and 74 in the
forward
portion of the buckle 38 (see FIG. 3). The line-drilling operation forms the
grooves 41
and 43 described above. A press-fit shear pin 76 is then installed engaging
the holes 72
but not the grooves 41 or 43. Optionally, the holes 74 can be staked or
swaged. The shear
pin 76 is a representative example of a shear member. Other types of machine
elements
such as a square key could be used as a shear member in place of the circular-
cross-
section shear pin 76.
[0031] To subsequently assemble the strut fairing 10 in an engine, the tail
piece 26 is
slipped axially forward over the strut (not shown). Next, the nose piece 24 is
slipped
axially rearward over the strut and pivoted so the posts 32 engage the slots
62.
[0032] The shear pins 76 are then driven fully into place so that they engage
the grooves
41 and 43 as well as the holes 72 and 74. The swaged holes 74 act as a
secondary
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retention feature for the shear pins 76. Alternatively, the shear pins 76
could be staked or
swaged after being driven into place.
[0033] Finally, the radially outer ends of the nose and tail pieces 24 and 26
are secured
together with shear bolts 78 or other similar fasteners installed through
mating flanges 80
(see FIG. 2). Even without the shear pins 76 in place, interaction between the
pressure
face 42 and the forward wall 64 of the slot 62 resists movement of the nose
piece 24. If
the nose piece 24 should move in operation, it can only move to a position
which creates
an aft-facing step relative to the combustion gas flowpath, not an undesirable
forward-
facing step.
[0034] When the nose piece 24 and tail piece 26 are assembled with the shear
pins 76 in
place, interaction between the shear pins 76 and the grooves 41 and 43 resists
or blocks
relative radial movement of the nose piece 24 and the tail piece 26. (see FIG.
4) This
configuration prevents the nose piece from moving in operation, and therefore
avoids
both forward-facing steps and aft-facing steps relative to the combustion gas
flowpath. It
is noted that the shear pin feature and the taper feature may be incorporated
individually
or in combination.
[0035] The buckle-to-post joint can be disassembled by pressing the shear pins
76 out of
engagement with the posts 32 and 34. A simple manual or powered pin-press type
tool,
similar to a conventional chain pin tool (not shown) may be used for this
purpose.
[0036] FIGS. 5 and 6 depict an alternative strut fairing 110. Its
construction, including
material selection, is substantially identical to the strut fairing 10
described above except
for the configuration of the posts. Elements of the strut fairing 110 not
specifically
described in detail may be taken to be identical to the corresponding elements
of the strut
fairing 10. The strut fairing 110 includes an airfoil-shaped vane 112, outer
and inner
bands 114 and 116, and is split, generally along a common transverse plane, to
define a
nose piece 124 and a tail piece 126.
[0037] The nose piece 124 includes posts 132 which extend in a generally
radially
inward direction adjacent its aft face 128, and the tail piece 126 includes
posts 134 which
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extend in a generally radially inward directly adjacent its forward face 130.
When
assembled, the posts 132 and 134 are received in a slot of a metallic buckle
138. (It is
noted that to permit assembly, the posts 132 and 134 may be oriented in a
direction that
is not strictly radial to the engine centerline, but rather perpendicular to a
waterline cut
through the engine; that is, the posts 132 and 134 would be generally parallel
to each
other).
[0038] The posts 132 and 134 and the buckle 138 may be collectively configured
to
define a "tripod" contact configuration as described above.
[0039] Each of the posts 132 includes a mating face 140 facing the nose
piece/tail piece
split line, The mating face 140 incorporates an alignment element 141 defining
at least
one element that is protruding or recessed in the axial direction relative to
the remainder
of the otherwise planar mating face 140. In the illustrated example the
alignment element
141 is an "S-cut" or S-shaped profile or other similar shape (see FIG. 7). The
axis of the
S-cut extends perpendicular to a waterline cut through the engine, and may be
formed
during the same cut procedure used to split the nose piece 124 from the tail
piece 126.
[0040] Each of the posts 134 includes a mating face 146 facing the nose
piece/tail piece
split line, The mating face 146 incorporates an alignment element 143 defining
at least
one element that is protruding or recessed in the axial direction relative to
the remainder
of the otherwise planar mating face 146. In the illustrated example the
alignment element
143 is an "S-cut" or S-shaped profile or other similar shape (see FIG. 7). The
axis of the
S-cut extends perpendicular to a waterline cut through the engine, and may be
formed
during the same cut procedure used to split the nose piece 124 from the tail
piece 126.
The alignment element 143 is complementary to the alignment element 141 of the
post
132.
[0041] The buckle 138 is a monolithic structure including a slot 162 formed
therein.
When the nose piece 124 and the tail piece 126 are assembled to each other,
the mating
face 140 of each post 132 contacts the mating face 146 of the corresponding
post 134.
The slot 162 of the buckle 138 receives the posts 132 and 134.
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[0042] Once the buckle 138 has been dry-fitted and all assembly clearance
removed, the
buckle 138 is temporarily secured to the post 134. For example, the buckle 138
could be
tack-welded to the post 134. Alternatively, holes can be line-drilled through
the buckle
138 and the post 134, and a press-fit buckle pin 170 installed. The nose piece
124 can
then be removed, and the buckle 138 is rigidly secured to the post 134, for
example by a
known brazing process.
[0043] To subsequently assemble the strut fairing 110 in an engine, the tail
piece 126 is
slipped axially forward over the strut. Next, the nose piece 124 is slipped
axially
rearward over the strut and pivoted so the posts 132 engage the slots 162.
[0044] Finally, the radially outer ends of the nose and tail pieces 124 and
126 are secured
together with shear bolts 178 or other similar fasteners installed through
mating flanges
180 (see FIG. 6). When the nose piece 124 and tail piece 126 are assembled,
interaction
between the alignment elements 141 and 143 resists radial movement of the nose
piece
124 relative to the tail piece 126. More specifically, as shown in FIG. 8,
there is a
nonzero angle 0 between the long axis "L" of the alignment element 141 and a
radial
direction R. This relationship creates an interference condition which
prevents or blocks
relative movement of the nose piece 124 and the tail piece 126 in the radial
direction, and
therefore avoids both forward-facing steps and aft-facing steps relative to
the combustion
gas flowpath.
[0045] It is noted that the buckle-and-post configurations described herein
may be
employed at the inboard end of a split fairing, at its outboard end, or at
both ends.
[0046] The split fairing configuration described herein has several advantages
over prior
art designs, including: 1) Manufacturing tolerance relief, reducing cost. 2)
Assembly ease
through guided engagement, reducing cost. 3) Self-alignment of the joint,
resulting in a
zero-clearance fit. 4) Minimized flowpath gaps, abating wear. 5) Reduced
leakage
through flowpath gaps, improving engine performance. 6) Avoidance of forward
facing
steps into the flowpath, improving engine performance.
[0047] The present invention precludes the traditional tight tolerances
required on the
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WO 2014/022358
PCT/US2013/052672
post and buckle that are necessary to achieve a matched fit to facilitate
producibility,
assembly and limited leakage loss at the split line. The proposed invention
provides the
added benefits of preventing aerodynamically undesirable steps into the
flowpath at the
split line while further reducing buckle-to-post assembly gaps, leading to a
reduction in
backside pressurization air leaking into the flowpath.
[0048] Cost is reduced due to relaxed tolerances and simplified assembly. The
present
invention allows utilization of an "as-cast" buckle, as opposed to a precision
match
machined detail part.
[0049] The foregoing has described a split fairing buckle joint for a gas
turbine engine.
While specific embodiments of the present invention have been described, it
will be
apparent to those skilled in the art that various modifications thereto can be
made without
departing from the spirit and scope of the invention. Accordingly, the
foregoing
description of the preferred embodiment of the invention and the best mode for
practicing
the invention are provided for the purpose of illustration only and not for
the purpose of
limitation.
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