Note: Descriptions are shown in the official language in which they were submitted.
~2~ 7
13DV-9908
ULTRA HIGH BYPASS ENG I NE INTEGRATED FAN/COUL
AN~ TRANSPORTATION/REMOVAL
BACKGROUND OF THE INVENTION
The present invention r~lates to a method and
apparatus for assembly and mounting of a turbofan gas
turbine engine and. more particularly. to integration
of an engine fan casing with en8ine cowlinB and
mounting arran~ement which permits disassembly of the
core en8ine from the external fan assembly.
Turbofan gas turbine engines gencrally include a
core en~ine coupled in driving relationship to a
forward mounted fan module. The fan module, in a
high-bypass ratio en~ine. includes a l~arge diam~ter
sin~le stage fan and a multiple stage intermediate
pressure compr~ssor or booster. The fa~ is surroundsd
by a fan casing supported by a plurality of structural
lS outlet guide vanes which are. in turn, support~d on a
casing surrounding the booster. The core en8ine
includes a hi8h pressure compressor, a combustor an~ a
multi-stage turbine for extracting energy from
combusticn gases exiting the combustor for triving the
compressors and fan.
13DV-9908
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Mounting of such high-bypass engines on an
aircraft generally requires one or more structural
supports which connect the engine to a structural
member. sometimes referred to as a strut or pylon, in
a wing or fuselage, depending upon the mounting
location. The structural supports extend throu~h an
aerodynamic cowling, sometime- referred to as a
nacelle, and couple to the en~ine casing. Coupling
may be to the fan casing (or shroud) and to the casin~
surroundin~ the turbine. In general, some form of
structural yoke is attached to the en~ine casing and
the structural supports attach to the yoke.
As gas turbine en~ines have beccme more powerful
and larger, a concern has develop0d with handlin~ ant
lS transporting of such enginas. In particular, engines
are now bein~ developed with fans and fan casings
having diameters in the range of twelve feet.
Transporting of such engines b~ air or ground i~ not
practical with current commercial aircraft and over
the road transportation guidelines. Accordingly, it
is desirable to provide a method of assembling such
engines which permits transport without exceeding
aircraft or ground transport size limitations.
The problems associated with handl ing and
transporting of such large en~ines extends beyond
shipments to the installation, removal, and handling
of the ensines in aircraft s*rvicin~. It is therefore
further desirable to provide a methot and apparatus
for servicing of such engines which overcomes the
problems associated with such large diameter fans.
13DV-9908
~ 3 ~ 2~2~7
SUMMARY OF THE INVENTION
It is an object of the present invention to
provide a method and apparatus for asssmbly and
mounting of a hi~h-bypass ratio gas turbine en~ine
which overcomes the above mentioned disadvantages of
such engines.
It is another object of the present invention to
provide a method and apparatus which permits
separation of the fan and core en~ine plus boo~t~r
without affectin~ acceptance testin8 of the ~ngin~.
It is yet another object of the present invention
to provide a method and apparatus for incorporation of
a fan shroud into an en8ine nacelle with structural
support for the core en8ine derived from the nacelle.
The above and other objects. features and
advantages are attained in one form in a high-bypass
ratio ~as turbine en~ine in which the fan casing is
incorporatet into an aircraft mounted cowling or
nacslle and the fan casing is made separable from the
core engine without disturbing ass~mbly of the
intermediate stage or booster compressor. The nac~lle
is modified to become a structural m~mber ant is
structurally attached to at least one aircraft frame
member or strut. Outlet ~uide vanos, normally
couplin~ th~ fan shrout to the boo~ter casing. are
connected between the nacelle and tho booster frame to
support th~ en~ine within the nacelle. The connectir,3
supports are made separable from the booster casin~ to
allow the cor~ enBine plus booster to be removable
from the nacelle. Still further, the fan spinner and
fan blades are made removable from the en~ine without
disturbin~ the booster sta~e or removing the core
engine. The entire core en~lne is thus intact and can
l3DV-9908
~ 4 - 2~0~7
be tested as a unit. Ths fan blades can be installed
on the en~ine for testing purposes and removed for
transporting. Such an arran8ement maintains the
integrity of the assembled rotating components, e.~.,
S the compressor, turbine, booster and fan rotor, while
allowing separation of elements which are either non-
rotatin3 or do not require a rotating interface, such
as, for example, the nacelle, outlet guide vanes and
the fan blades. Although the fan blades rotate, their
connection is a fixed attachment to the fan rotor and
does not require a rotatirg interface.
In another form, the turbine en~ine may be
characterized as comprisin~ a ~enerally cylindrical
stator module transportable as a sin~le unit and
includin8 an inte~rated fan casei fan cowl, and inlet.
The en~ine further comprises a rotor module
transportable as a single unit and including a core
en8ine with a rotatable fan rotor. The rotor module
is removably attachable to the stator module. A
plurality of fan blades i5 removably at~achable to the
fan rotor. The stator module may includa a plurality
of circumferentially spaced and radially depending fan
struts attached at one end along an inner surface of
the stator module. Another end of the fan struts may
25 be removably attachable to the rotor module for
supporting the rotor module within at least part of
the stator module. At least some of th~ fan struts
may project substantially perpendicular towart the
centerline of the rotor module while others of the fan
struts may comprise structural outlet guide vanes
which project obliquely toward th0 centerlino of the
rotor module. A spinner is desirably removably
attached to the fan rotor forwart of the fan blades.
13DV-9908
- 5 ~ 7
The invention may b0 further characterized as a
method for assembling a turbo-fan en~ine having a
rotor module including a core enBine with a rotatable
fan rotor and furthsr having a stator module including
an inte~rated fan casing. fan cowl and inlet. The
method comprises removably attachin8 the rotor motule.
as a sinsle inte8rated unit. to the stator module ant
thereafter attaching a plurality of fan blades to the
fan rotor. The method may further comprise affixing a
plurality of circumferentially spaced fan struts to
the stator module with the fan struts extending
generally radially from the stator module toward the
rotor module and removably attachin~ inner ends of the
fan struts to the rotor module for supporting the
rotor module at least partially within the stator
module.
BRIEF ~ E~ OF THE DRAWINGS
For a botter und~rstanding of the present
invention. reference may be had to the following
detailed description taken in conjunction with the
accompanyin8 drawings in which:
FIG. 1 is a simplified partial cros~-sectional
drawing of an exemplary gas turbine engine:
FIG. 2 is a ~implified drawin~ showin~ mounting cf
the en8in~ of FIG. 1 on an aircraft win~:
FIC. 3 is a simplified drawing showing an en~ino
arran8ement in accordance with the present invention
mounted to an aircraft win~; and
FIG. 4 i5 an exploded view of the en8ine
arran8ement of FIG. 3 showing engine disa-~sembly.
13DV-9908
- 6 - 2~21~3 1
DESCRIPTION OF THE PRFFERRED EM~ODIMENT
Referrin3 first to FIG. 1, there is shown a
partial cross-sectional drawin~ of an exemplary high-
bypass ratio gas turbine en8ine 10 having a core
enBine portion indicated at 12 and a fan portion
indicated at 14. The core en8ine or core engine
portion 12 may be referred to as the rotor module
while the fan portion 14 may be referred to as the
stator module. In ~eneral, a_ least so~e ext nt of
the rotor module lies within the stator module. The
rotor module or core engine 12 includes an
intermetiate pressure compressor or booster sta~e 16,
a high pressure compressor stage 18. a combustor stage
20, a hiBh pressure turbine sta~e 21, and a low
lS prsssure turbine stage 22 all aligned on an en8ine
centerline 23. The fan portion 14 inclutes a
plurality of fan blades 24. a fan shroud 26. a fan
spinnsr 28 and a plurality of circumferentially spaced
outlet guide vanes 30 which support the fan shroud 26.
The vanes 30 are attached to en8ine casing 32 adjacent
the booster stage 16. The en~ine 10 aIso includes an
aft core cowl 33 and a primary nozzl~ 35. A fan shaft
37 driv~n by turbine stage 22 extends throu~h the
engine and is coupled in drivin~ relationship with
booster stage 16 and fan blades 24 via a fan rotor 45.
The high pressure turbine stage 21 drives a compressor
stage 18 through a hi~h pressure shaft 41.
As will be apparent from FIG. 1. handling of the
engine 10 is a major problem for very largè diamater
fan blates 24. While it is possible to remove the
blades 24. the practice in the art is to treat the
blades 24. booster sta~e 16, and casing 26 as a
unitary module. Some engines are constructed with a
13DV-9908
~ 7 ~ 2 ~ 210 8 7
two-piece fan shaft 37 separable aft of the boostsr
sta~e 16 approximately along the line 43. These
en8ines are identified as n sp 1 i t fan~ engines.
Assembly and/or disassembly of split fan engines is
complicated since it is difficult to attach the fan
forward shaft and the fan mid ~haft properly. In such
fan split methods of separating an en~ine. the forward
module or fan module includes the fan shroud 26,
structural outlet guide vanes 30, fan spinner 28, fan
rotor blades 24. alon~ with Ih0 fan rotor. booster
sta~e 16 and the forward portion of shaft 37. Thus,
it has not been practical to separate the fan module
and large external components from the core en8ine to
facilitate handlin~. Furthermore, it is not desirable
to separate an engine where such separation includes a
rotatin8 interface since such interface may involve
bearings or critical alignments.
Turnin~ now to FIG. 2. there,is shown a simplified
cross-sectional view of an en8ine similar to that of
FIG. 1 mounted within an aerodynamic fan cowl 34 which
is in turn coupled via a structural member 36 to an
aircraft wing 33. The structural m~mber 38 and
cowlin~ 34 are well known in the art and may be of the
type shown. by way of example, in U.S. Patent No.
~5 4.132.069. Within the fan cowl 34, the member 36 is
connected to the fan shroud 26. The shrout 26 is
releasably connected to the cowl 34. The cowl 34
preferably includes an inlet section 37.
FIG. 3 illustrates an arranBement in accordance
with the tea~hing of the present invention in a
stylized repr~sontation of a turbofan en8ine. The fan
cowl, indicated at, 40, is an inte~rated cowl
incorporating the aerodynamic characteristics of the
cowl 34 but incluting the structural features of a fan
.
.
13DV-9908
- 8 - 2~2~a~7
casin~. In partic~lar, the fan shrout 26 is now an
integrated part of cowl 40 as shown by the increased
thickness in the cross-sectional dimensions of FIG. 3.
The structural member 36 attaches to the cowl 40. or
S rather to the structural portion of the cowl 40
inticated by cross-sectional members 42. The outlet
guide vanes 30 connect to the inte8rated cowl 40 and
support the core enBine at essentially the same
location as in FIG. 2. Each of the vanes 30 is
rcleasably connected to a booster casing 44 by bolts
or other suitable means (not shown) at the location
indicated at 46. The casin~ 44 may be referred to as
the forward core cowl and is integral with the frame
of the rotor module. The vanes 30 are
circumferentially spaced within the cowl 40 and depend
radially from an inner surface of the cowl toward the
casing 44. At least some of the vanes 30 are affix~d
to the structural members 42 at their respective ends
adjacent the inner surface of cowl 40. The dependin~
ends of the vanes 30 are adapted for releasable
attachment to the casing 44. The vanes 30 thus act as
support members or struts for supportin~ at least a
portion of the rotor module 12 at least partially
within the stator module 14. While the vanes 30
extend substantially perpendicularly with respect to
the enBine centerline 23, additional support is
provid~d by struts 48 which extend obliquely from a
connection point 50 adjacent the affixed ends of vanes
to a connection point 52 on the forward core cowl
or casing 44. The engine 10 may include a yoke (not
- shown) or other mounting arran~ement for releasably
attachinR the ends of the struts 48 to tho rotor
module lZ.
13DV-9908
9 ~ 8 7
FIG. 4 is an exploded view of the en~ine assembly
of FIG. 3 which illustrates the ssparable elements of
the en~ine. In particular, the fan blades 24 along
with the fan spinner 28 are removable from the rotor
module 12 and can be disassembled from the rotor
module without removing the engine nacelle 40. The
blades 24 are preferably individually detachable from
a rotatable fan rotor 45 which also is part of the
core en8ine and is coaxial with centerline 23. The
method of conn~ctin~ or removably attaching the vanas
30 to the fan~rotor 45 may be any of the methods well
known to those skilled in the art including methots
presently used for attachin3 such fan blades to fan
rotors in commercially available turbofan engines.
The fan rotor 45 is attached to the fan shaft 37 (seen
in FIC. l) for transferring power from the low
pressure turbine stage 22 to the fan blades 24 and
booster compressor sta~e 16.
The rotor module 12 is disconnectable or
releasable from the vanes 30 and struts 48 at the
connection points 46 and 52, r~spectively, leaving the
vanes 30 and struts 48 in their affixed dependin~
position as shown in FIG. 4. Note also that the aft
core cowl 33 may also be removed from the rotor module
12 to facilitate handling and transportin~ of the
rotor module. Other accessory components indicated
~enerally at 58 such as9 for example, an elect~ic
generator and a hydraulic pump, may also be removet
from the rotor motule 12 for ease of handling. The
items which can be remo~ed from the core engine or
rotor module 12 also represent items which can be
replaced without affectin~ th~ inte~rity of the rotor
module and requirin~ test stand operation prior to
returning the en8ine to flight status. For en8ine
:
13DV-9908
- lO- 2~21~7
replacement alone, i.e., to replace only the rokor
module 12, it is only necessary to remove the access
pan~ls (not shown) in the nacelle 40 to provide access
to the connection points of the fan blades 24, outlet
guide vanes 30 and struts 48 at the rotor motule.
With the fan blades 24 and spinner 28 removed, the
rotor module 12 may be disconnected from the stator
module 14 and moved in an aft direction to separate
the two components. One advantage of this arran8ement
is that the rotor module 12 may be removed from an
aircraft without removing the nacelle 40. A more
si~nificant advantage is that the rotatin~ components,
all of which are inte~ral with the rotor module, are
separable from the en~ine 10 as an integral unit,
lS i.e., the rotor module 12, so that the op~rational
int~rity of the en~ine is not compromised by
transporting the rotor motule separately from the
stator module.
In use, the en~ine 10 can be fully assembled,
performance tested and the fan blades 24 removed for
transport. At an aircraft, the en8ine nacelle 40 is
installed, followed by connection of the rotor module
or core en8ine 12 to the nacelle by means of the
forward struts 48 and outlet guide vane~ 30 ant an aft
support 56 (the aft support 56 may be substantially
identical to aft sUpportc now in commercial u8e for
supporting engines such as 10 to an aircraft). The
fan blades 24 and spinner 28 are thereafter connected
to the en~ine 12 to completa assombly. Alternately,
the en~ine 10, or replacement components thereof, may
be assembled after transportin~ but prior to
installation on an aircraft. Similar}y, while removal
of the rotor module 12 provides an advanta~eous method
of replacin~ or repairing a core engine, there may be
13DY-9908
2~7
.
occasions in which it is desirable to remove the
entire engine, i.e., the rotor and stator modules, as
an integral unit and perform disassembly after such
removal. Both methods are contemplat~d by the pr~ent
S invention.
While the principles of the invention have now
be~n made clear in an illustrative embodiment, it will
become apparent to those skilled in the art that many
modifications of the structures, arrangements, and
components presented in tho above illustrations may be
made in the practice of the invention in order to
develop alternate embodiments suitable to specific
operatin~ requirements without dep~rting from the
spirit and scope of the invention as set forth in the
claims which follow.
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