Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
ELECTRIC POWER SYSTEM FOR POWERPLANTS OF A MULTI-ENGINE
AIRCRAFT
[0001] The present invention relates generally to hybrid and electric
powerplants for
aircrafts, and more particularly to a multi-engine aircraft powerplants.
BACKGROUND
[0002] Developments in hybrid and/or electric powerplant architectures for
aircrafts
continue. In general terms, such aircraft engines include an electric motor
that is
powered by an electrical system that includes batteries. In order to meet
certification
requirements for hybrid and/or electric aircraft engines, such powerplants are
required
to have back-up battery/batteries, should a failure of the electric portion(s)
of the
powerplant(s) occur during critical moments (e.g. take-off). In the case of
multi-engine
aircrafts, the addition of such back-up batteries for multiple powerplants
represents
significant extra weight.
SUMMARY
[0003] There is accordingly provided a multi-engine aircraft comprising: two
or more
powerplants configured for providing motive power to the aircraft, each
including an
electric motor; and an electric power system controlling electrical
distribution and
operatively connected to the electric motors, the electric power system
including
primary battery packs, each operatively connected to the electric motor of a
respective
one of the two or more powerplants, the electric power system further
including a
reserve battery pack and a switch interconnecting the reserve battery pack and
the
electric motors, the reserve battery pack shared by the electric motors by the
switch
and configured such that the reserve battery pack provides electric power to a
selected
one of the electric motors.
[0004] There is also provided an electric power system for controlling
electrical
distribution in a multi-engine aircraft, the multi-engine aircraft comprising
two or more
powerplants each including an electric motor, the electric power system
comprising:
primary battery packs operatively connected to respective ones of the electric
motors, a
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reserve battery pack, and a switch operatively connected to the reserve
battery pack
and to the electric motors, the electric power system configured for:
detecting a need for
supplementary electric power to be supplied to a selected one of the electric
motors;
and responsive to detecting the need, commanding the switch to provide access
to
electric power from the reserve battery pack to the selected one of the
electric motors.
[0005] There is also provided a method of distributing electric power in a
multi-engine
aircraft having two or more powerplants each having an electric motor, the
method
comprising: detecting a need for supplementary electric power to be supplied
to one of
the electric motors; and responsive to detecting said need, commanding a
reserve
battery pack to supply electrical power to said electric motor.
[0006] There is further provided a multi-engine aircraft comprising: a first
powerplant
and a second powerplant, the first powerplant including a first electric
motor, the second
powerplant including a second electric motor; and an electric power system
controlling
electrical distribution to and operatively connected with the first and second
electric
motors, the electric power system including a first primary battery pack
operatively
connected to the first electric motor and a second primary battery pack
operatively
connected to the second electric motor, a reserve battery pack, and a switch
operatively
connected to the reserve battery pack and the first and second electric
motors, the
switch operative to provide access to electric power from the reserve battery
pack to a
selected one of the first and second electric motors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Reference is now made to the accompanying figures in which:
[0008] Fig. 1 is a schematic axial cross-section view of an exemplary
powerplant
shown as a hybrid gas/electric multi-spool turboprop turbine engine;
[0009] Fig. 2 is a schematic representation of an exemplary multi-engine
aircraft with
two powerplants such as that shown in Fig. 1; and
[0010] Fig. 3 is a block diagram of an exemplary controller of an electric
power system
of the multi-engine aircraft shown in Fig. 2.
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DETAILED DESCRIPTION
[0011] The present disclosure is directed to a multi-engine aircraft 1. The
multi-engine
aircraft 1 includes two or more powerplants 10 including an electric motor 30,
and an
electric power system 40, each of which is described in more detail below.
[0012] An example of powerplant 10 is shown in Fig. 1, which is a schematic
exemplary
representation of an axial cross-section view of a hybrid-electric powerplant
10A, more
particularly in this example a hybrid gas/electric multi-spool turboprop
turbine engine
10A (or simply "hybrid turbine engine" 10A). Even though the following
description and
accompanying drawings specifically refer to a turboprop turbine engine as an
example,
it is understood that aspects of the present disclosure may be equally
applicable to
other types of powerplants 10 such as turboshaft turbine engines, for
instance.
[0013] In the depicted embodiment, the hybrid-electric powerplant 10A, in this
case the
hybrid turbine engine 10A, has a combustion engine 10' (or said differently a
combustion engine 10' portion) and is of a type preferably provided for use in
subsonic
flight to drive a load such as a propeller 11 via a reduction gear box 12
(referred
hereinafter as "RGB 12"). The RGB 12 is configured to transfer motive power
from a
gearbox input shaft 13 to an output shaft 14 coupled to propeller 11. The RGB
12 may
be of the speed-reducing type so that the gearbox output shaft 14 may rotate
at a
rotational speed lower than a rotational speed of the gearbox input shaft 13
and so that
the propeller 11 may be driven by the output shaft 14 at a suitable speed. A
power
turbine 15 may provide rotational motive power to drive the propeller 11 via a
turbine
shaft 16 (i.e., low pressure shaft), the gearbox input shaft 13, the RGB 12
and the
gearbox output shaft 14. In the depicted embodiment, the hybrid turbine engine
10A
comprises a first spool comprising a high pressure turbine 17, a high pressure
compressor 18 and a high pressure shaft 19, and, a second spool comprising a
low
pressure power turbine 15 mounted to a power turbine shaft 16.
[0014] The power turbine shaft 16 has a shaft axis of rotation SA. In some
embodiments, the shaft axis of rotation SA may correspond to a longitudinal
axis (e.g.,
central axis) of the hybrid turbine engine 10A. In some embodiments, the shaft
axis of
rotation SA may correspond to an axis of rotation of the propeller 11 and/or
shaft axis of
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rotation SA may correspond to an axis of rotation of a low-pressure spool
and/or a high-
pressure spool of the hybrid turbine engine 10A.
[0015] The compressor 18 draws ambient air into the engine 10A via air
inlet(s) 20,
increases the pressure of the drawn air and deliver the pressurized air to a
combustor
21 where the pressurized air is mixed with fuel and ignited for generating an
annular
stream of hot combustion gas(es) (referred hereinafter in the singular). The
high
pressure turbine 17 extracts energy from the hot expanding combustion gas and
thereby drive the high pressure compressor 18. The hot combustion gas leaving
high
pressure turbine 17 may be accelerated as it further expands, flows through
and drives
the power turbine 15. The combustion gas may then exit the hybrid turbine
engine 10A
via exhaust outlet(s) 22 defined by exhaust duct(s) 23.
[0016] The first and second spools of the hybrid turbine engine 10A may not be
mechanically coupled together so that they may rotate at different speeds
and/or in
opposite directions. Also, as shown, the air flow through the hybrid turbine
engine 10A
is generally toward a forward direction (see "FWD" shown in Fig. 1) of the
hybrid turbine
engine 10A where air inlet(s) 20 is disposed in a portion of the hybrid
turbine engine
10A aft (see "AFT" shown in Fig. 1) of the combustor 21 and exhaust outlet(s)
22 is
disposed in a portion of the hybrid turbine engine 10A forward of the
combustor 21. The
FWD direction illustrated in Fig. 1 may correspond to a direction of travel of
the hybrid
turbine engine 10A when the hybrid turbine engine 10A is mounted to an
aircraft and
configured as a turboprop engine. The exemplary configuration of the hybrid
turbine
engine 10A shown in Fig. 1 may be referred to as a reverse-flow free turbine
engine in
relation to the general flow direction (in the FWD direction) in the gas path
during gas
operation of the hybrid turbine engine 10A.
[0017] As seen in Fig. 1 and 2, the hybrid-electric powerplant 10A, in this
case a hybrid
turbine engine 10A as discussed above, comprises an electric motor 30, which
may
have a motor drive 30A (Fig. 2), operatively interfacing with the electric
motor 30 and
one or more components of the electric power system 40. The electric motor 30
is
configured to transfer motive power to the load (e.g., propeller 11) coupled
to the hybrid
turbine engine 10A. In other words, the hybrid-electric powerplant 10 includes
a
combustion engine 10A', which in the depicted embodiment is a turbine engine
10A' of
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the type of a turboprop turbine engine, and an electric motor 30, which may
thus
together be referred to as a hybrid turbine engine 10, where the gas turbine
combustion
engine 10A' and the electric motor 30 are drivingly engaged to a common load.
The
combustion engine 10A' portion of the hybrid-electric powerplant 10A performs
the
function of the engine control and propeller blade angle modulation and
associated
protective and indication functions. In the depicted embodiment, the electric
motor 30 is
at least partially disposed in the radially-inner space 24 defined by the
exterior of the
exhaust duct 23 and radially converging in the aft direction as indicated in
Fig. 1. As
shown, in this embodiment, the electric motor 30 is disposed axially between
the RGB
12 and the power turbine 15 along the shaft axis of rotation SA. The electric
motor 30
may be disposed somewhere else in other embodiments.
[0018] In an embodiment, the electric motor 30 is selected to be sufficiently
powerful to
drive the propeller 11 either without using fuel in the combustion engine 10A'
or with
using a reduced amount of fuel by the combustion engine 10A' during at least
one
mode of operation of the hybrid-electric powerplant 10A. The electric portion
of the
hybrid-electric powerplant 10A may thus assist in power increase for the
combustion
engine 10A' portion, or provide full power to drive the propeller 11, without
using fuel,
depending on the embodiment.
[0019] In the depicted embodiment, electric power for driving the electric
motor 30 is
distributed by the electric power system 40. The electric power system 40
controls the
electrical distribution and is operatively connected to the electric motor 30.
The electric
power system 40 includes an electric power source 41, which in the embodiment
shown
includes a primary battery pack 42. The primary battery pack 42 (or simply
"battery
back" hereinbelow) is operatively connected to the electric motor 30. The
electric power
source 41 may have more than one battery packs 42 in some embodiments. For
instance, in an alternate embodiment, the hybrid-electric powerplant 10A has
more than
one electric motor 30 coupled to the combustion engine 10A', and each one of
the
electric motors 30 of the hybrid-electric powerplant 10A has a respective
battery pack
42 operatively connected thereto. The electric power source 41 also includes a
reserve
battery pack 44, as will be described in further detail below.
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[0020] The battery packs (42, 44) may be any suitable type of battery, and
although
each illustrated as a singular battery, may be composed of any suitable number
of
batteries. In some other embodiments, the battery packs (42, 44) may be a
supercapacitor, a fuel cell, or other device for storing electrical energy or
using which
electrical energy may be produced.
[0021] In a particular embodiment, the battery pack(s) 42 are rechargeable,
such that
during operation of the hybrid-electric powerplant 10A, one or more electric
motors 30
may operate as generators to recharge the battery pack(s) 42, when the hybrid-
electric
powerplant 10A is in a mode of operation where no power is required from the
electric
motors 30 on the load driven by the hybrid-electric powerplant 10A. The
combustion
engine 10A' of the hybrid-electric powerplant 10A may also recharge the
battery pack(s)
42 in a mode of operation of the hybrid-electric powerplant 10A. For instance,
in an
embodiment, a generator is operatively connected to the combustion engine
10A', such
that power generated from said combustion engine 10A' may be supplied to the
generator for then charging the battery pack(s) 42. Alternately, the battery
pack(s) 42
may be recharged via a separate generator, not operatively connected to the
combustion engine 10A', such as a dedicated generator for charging the battery
pack(s)
42, or a dedicated generator associated with each battery pack 42. The multi-
engine
aircraft 1 may thus have a number of generators each operatively connected to
a
respective one of the battery packs 42. In an alternate embodiment, the
electric power
source 41 includes, for example, an auxiliary power unit (APU) for providing a
source of
electrical power to the aircraft or a pneumatic power for cabin air inside the
aircraft or
for recharging the battery pack(s) 42, and/or an electric generator from
another
powerplant 10 which may also be mounted to the aircraft.
[0022] The electric power system 40 includes a controller 43 configured to
control the
operation of the electric motor 30 by providing suitable control signals to
the electric
motor 30 and/or providing suitable conditioning of the electric power supplied
to the
electric motor 30 by the electric power source 41. In some embodiments, the
electric
power system 40, via its controller 43 or otherwise, is configured to control
the
operation of the electric motor 30 when the electric motor 30 operates as a
generator
(e.g., to recharge the battery pack 42) in at least one mode of operation of
the hybrid-
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electric powerplant 10. In other words, the electric motor 30 may be operating
as a
motor or as a generator, depending on the mode of operation of the hybrid-
electric
powerplant 10. The electric motor 30 operating as a generator for at least one
of the
battery pack(s) 42 may charge the pack 42 associated therewith, or the
electric motor
30 may charge the pack 42 associated with another one of the electric motors
30 of the
same or another powerplant 10. In an embodiment where the multi-engine
aircraft 1 has
at least one generator (separate from the electric motor(s) 30), the electric
power
system 40, via its controller 43 or otherwise, is configured to command the
generator(s)
to charge the battery pack 42 of the powerplant 10, or the battery pack 42 of
each one
of the powerplant 10. The controller 43 may actuate the amount of electric
power
supplied to the electrical motor 30 in response to control signals it
receives, such as for
example, commands sent via a control interface (e.g., panel) 50 from a pilot
of an
aircraft to which the powerplant 10 is mounted.
[0023] Referring to Fig. 3, the controller 43 may be embodied, partly or
entirely by a
computing device 70. The computing device 70 comprises a processing unit 71
and a
memory 72 which has stored therein computer-executable instructions 73. The
processing unit 71 may comprise any suitable devices configured to implement
the
functionality of the controller 43 and/or the electric power system 40
described herein,
such that instructions 73, when executed by the computing device 70 or other
programmable apparatus, may cause the functions/acts/steps performed by the
controller 43 and/or the electric power system 40 to be executed. The
processing unit
71 may comprise, for example, any type of general-purpose microprocessor or
microcontroller, a digital signal processing (DSP) processor, a central
processing unit
(CPU), an integrated circuit, a field programmable gate array (FPGA), a
reconfigurable
processor, other suitably programmed or programmable logic circuits, custom-
designed
analog and/or digital circuits, or any combination thereof.
[0024] The memory 72 may comprise any suitable known or other machine-readable
storage medium. The memory 72 may comprise non-transitory computer readable
storage medium, for example, but not limited to, an electronic, magnetic,
optical,
electromagnetic, infrared, or semiconductor system, apparatus, or device, or
any
suitable combination of the foregoing. The memory 72 may include a suitable
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combination of any type of computer memory that is located either internally
or
externally to device, for example random-access memory (RAM), read-only memory
(ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-
optical memory, erasable programmable read-only memory (EPROM), and
electrically-
erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or
the like. Memory 72 may comprise any storage means (e.g., devices) suitable
for
retrievably storing machine-readable instructions 73 executable by processing
unit 71.
[0025] The methods and systems for distributing electric power in a multi-
engine
aircraft as described herein may be implemented in a high level procedural or
object
oriented programming or scripting language, or a combination thereof, to
communicate
with or assist in the operation of a computer system, for example the
computing device
70. Alternatively, the methods and systems described herein may be implemented
in
assembly or machine language. The language may be a compiled or interpreted
language.
[0026] Embodiments of the methods and systems described herein may also be
considered to be implemented by way of a non-transitory computer-readable
storage
medium having a computer program stored thereon. The computer program may
comprise computer-readable instructions which cause a computer, or more
specifically
the processing unit 71 of the computing device 70, to operate in a specific
and
predefined manner to perform the functions described herein.
[0027] Computer-executable instructions may be in many forms, including
program
modules, executed by one or more computers or other devices. Generally,
program
modules include routines, programs, objects, components, data structures,
etc., that
perform particular tasks or implement particular abstract data types.
Typically the
functionality of the program modules may be combined or distributed as desired
in
various embodiments.
[0028] The electric power system 40 may be configured to supply enough
electric
power to the electrical motor 30 in order to produce some or all of the torque
required to
rotate the propeller 11 during at least one mode of operation of the aircraft.
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[0029] However, there may be a need to provide supplementary electric power to
the
electric motor 30 or the battery pack 42. In some instances, such need may be
caused
by a failure of the battery pack 42, which may not supply enough (or not
supply at all)
electric power to the electric motor 30. A proper electric power distribution
is thus
required to alleviate this for the powerplant 10 and/or the multi-engine
aircraft 1 as a
whole. The electric power system 40 therefore includes a reserve battery pack
44
providing electric power to the electric motor 30 when the electric power
system 40
detects a need for supplementary electric power to be supplied to the electric
motor 30.
Upon detecting such need, the electric power system 40 commands the reserve
battery
pack 44 to supply electric power to the electric motor 30 and/or the battery
pack 42
associated with the electric motor 30. For sake of clarity the battery pack 42
will be
referred to as the primary battery pack 42. Operation of the electric power
system 40 is
described below in the context of the multi-engines aircraft 1.
[0030] Referring to Fig. 2, the multi-engine aircraft 1 is schematically
illustrated. The
multi-engine aiarcraft 1 has two powerplants 10, which are, more particularly
in this
embodiment, two hybrid-electric powerplants 10A, however can also include more
than
two powerplants 10 in other embodiments, each including a combustion engine
10A'
and an electric motor 30, where the combustion engine 10A' and the electric
motor 30
are drivingly engaged to a common load, as discussed above. In the illustrated
embodiment, the hybrid-electric powerplants 10A drive respective loads, which
in this
case are respective propellers 11. In other embodiments, the hybrid-electric
powerplants 10A may be compounded and drive a common load, together with their
respective electric motor 30 and combustion engine 10A'. In other embodiments,
the
loads may be other than propellers 11, for instance a fan of a turbine engine,
or else in
other embodiments. Although the depicted embodiment of the multi-engine
aircraft 1
has hybrid-electric powerplants 10A only, the multi-engine aircraft 1 may have
one or
more of the powerplants 10 fully electric, meaning that one or more of the
powerplants
may not have a combustion engine 10A' portion and include one or more electric
motors 30 to drive a load in alternate embodiments. Such powerplants 10 would
be
referred to as electric powerplants. The multi-engine aircraft 1 may thus
comprise two
or more powerplants 10 from which one or more is/are hybrid-electric
powerplant(s)
10A and one or more is/are electric powerplants in alternate embodiments.
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[0031] As shown, the multi-engine aircraft 1 includes a fuel system 60. The
fuel system
60 distributes the required fuel to power the combustion engine(s) 10A' of the
multi-
engine aircraft 1. The fuel system 60 may thus include one or more fuel
reservoir(s),
pump(s), piping and a fuel distribution controller(s). The fuel system 60 may
be
connected to the control interface 50 (discussed previously), but not
operatively
connected to the electric power system 40.
[0032] The electric power system 40 controls the electric distribution to the
electric
motors 30 and are operatively connected thereto. The electric power system 40
includes a primary battery pack 42 operatively connected to each of the
electric motors
30. In other words, each electric motor 30 has a primary battery pack 42
operatively
connected to it, such that the electric motors 30 have a respective primary
battery pack
42 associated with each of them. In some embodiments, one or more electric
motors 30
have more than one primary battery pack 42 associated therewith. It may be
desirable
to have electrical redundancy within the multi-engine aircraft 1 and
powerplants 10, so
that if the primary battery pack 42 associated with a given one of the
electric motors 30
fails (e.g. fails to deliver sufficient amount of electric power to its
associated electric
motor 30 during operation of the powerplants 10), a power source reserve/back-
up as
described below may continue to supply a suitable amount of electric power to
said
electric motor 30.
[0033] The electric power system 40 includes a single reserve battery pack 44
operatively connected to a selected one of the electric motors 30 of the two
(or more)
powerplants 10. In other words, in the depicted embodiment, contrary to the
primary
battery packs 42 associated with respective ones of the electric motors 30,
the reserve
battery pack 44 may be operatively connected to more than one electric motor
30 That
is, the reserve battery pack 44 of the electric power system 40 may supply
electric
power to one of the electric motors 30, which is selected once identified as
having a
need for electric power. This may occur, for instance, when the electric power
system
40 detects a failure of the primary battery pack 42 associated with one of the
electric
motors 30. Such selection may be performed by components of the electric power
system 40, such as the controller 43 discussed above, or other suitable
components,
such as an electrical switch (physical or software switch), for instance. The
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component(s), as for instance the switch, operatively connected to the
electric motors
30 and the reserve battery pack 44 may provide access to electric power from
the
reserve battery pack 44 to the selected electric motor 30.
[0034] The reserve battery pack 44 may be selected to be capable of supplying
sufficient amount of electric power to one of the electric motor 30 at a time,
in any mode
of operation of the powerplant(s) 10. In instances where the primary battery
pack 42
that failed and associated with one of the electric motor 30 is unable to
supply electric
power (totally unable or unable to provide sufficient amount of electric
power), the
electric power system 40 may command the reserve battery pack 44 to supply the
electric motor 30 in need for electric power. Such supply may be allowed via
the
selection component(s) interfacing between the electric motors 30 and the
reserve
battery pack 44 discussed above.
[0035] The reserve battery pack 44 may take different forms. In an embodiment,
the
reserve battery pack 44 is a non-rechargeable (or "single use") battery that
must be
changed once used, for instance. The reserve battery pack 44 may be a
rechargeable
one in other embodiments.
[0036] In the illustrated embodiment, the multi-engine aircraft 1 has a single
reserve
battery pack 44 operatively connected to the electric motors 30 of the two
hybrid-
electric powerplants 10A. This may minimize the overall weight of the multi-
engine
aircraft 1, as the amount of batteries and electrical redundancy is minimal.
There is thus
no need for duplicate components for forming the electric power system 40 and
reserve
power source of the multi-engine aircraft 1, which may advantageously reduce
weight
and/or simplify the electrical network forming the electric power system 40 of
the multi-
engine aircraft 1.
[0037] In the illustrated embodiment, the multi-engine aircraft 1 has a pair
of hybrid-
electric powerplants 10A, and the electric power system 40 has one reserve
battery
pack 44 per pair of primary battery packs 42 for providing electrical
redundancy to the
pair of hybrid-electric powerplants 10A. Although the multi-engine aircraft 1
shown has
only one pair of powerplants 10, which is in this case one pair of hybrid-
electric
powerplants 10A, there may have more than one pair of powerplants 10 / hybrid-
electric
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powerplants 10A in alternate embodiments. In such instances, the electric
power
system 40 has one reserve battery pack 44 for each pair of powerplants 10,
though as
discussed above, the multi-engine aircraft 1 may have only a single reserve
battery
pack 44 no matter the number of powerplants 10 in the whole aircraft.
[0038] In an embodiment, one or more of the hybrid-electric powerplants 10A
includes
a rotary engine compounded with their combustion engine 10A'. The rotary
engine may
take different form, where in a particular embodiment the rotary engine is a
Wankel
rotary engine. The rotary engine , the combustion engine 10A' and the electric
motor 30
of said one or more hybrid-electric powerplants 10A may be drivingly engaged
to the
common load via a gearbox (the RGB 12, or an additional gearbox mechanically
coupling the combustion engine 10A', the electric motor 30, and the rotary
engine). One
or more of the hybrid-electric powerplants 10 may include more than one rotary
engine,
in some embodiments.
[0039] Methods of distributing electric power in a multi-engine aircraft
having two or
more powerplants (10, 10A) may be implemented by the features of the multi-
engine
aircraft 1, powerplants 10 and electric power systems 40, some embodiments of
which
described herein. In an embodiment, a method comprises detecting a need for
supplementary electric power to be supplied to one of the electric motors 30,
and
responsive to detecting such need, commanding a reserve battery pack 44 to
supply
electrical power to said electric motor 30, for example via one or more
components of
the electric power system 40, such as the controller 43.
[0040] The above description is meant to be exemplary only, and one skilled in
the
relevant arts will recognize that changes may be made to the embodiments
described
without departing from the scope of the disclosure. Also, one skilled in the
relevant arts
will appreciate that while the systems, devices and turbine engines disclosed
and
shown herein may comprise a specific number of elements/components, the
systems,
devices and turbine engines could be modified to include additional or fewer
of such
elements/components. Modifications which fall within the scope of the present
invention
will be apparent to those skilled in the art, in light of a review of this
disclosure, and
such modifications are intended to fall within the appended claims.
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