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EADSEADS Innovation Works UK
Filton, Bristol BS99 7ARUnited Kingdom
Contact: [email protected]
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EADS Innovation Works
The E-Thrust concept study is part of EADS on-going
hybrid and electrical propulsion system research,
which has seen the hybrid concept study for a full-scale
helicopter, the successful development of a Cri-Cri
ultralight modified as the worlds first four-engine all-
electric aerobatic aircraft, the demonstration flights of a
hybrid electric motor glider for which EADS Innovation
Works developed the battery system, the flight testing
of a short-range mini-unmanned aerial vehicle with an
advanced fuel cell and the integration of a piston diesel
engine into the TANAN UAV as well as the concept study
of a hybrid-electric propulsion system for this rotorcraft.
EADS Innovation Works is the corporate network of
research centres of EADS. A highly skilled workforce
of more than 800 is operating the laboratories that
guarantee EADS technical innovation potential
with a focus on the long-term. The structure of the
network and the teams within EADS Innovation Works
are organised in global and transnational Technical
Capabilities Centres:
Composites technologies
Metallic technologies and surface engineering
Structures engineering, production processes and
aeromechanics
Sensors, electronics and system integration
Systems engineering, information technology and
applied mathematics
Energy and propulsion
Disruptive Scenarios and Concepts Center
RollS-RoyCE plC
65 Buckingham Gatelondon SW1E 6AT United Kingdom
Rolls-Royce Research and Technology
In 2012, Rolls-Royce invested 919 million on research
and development, two thirds of which had the objective
of further improving the environmental performance of
its products, in particular reducing emissions. To ensure
that there is a pipeline of technology, and a balanced
portfolio of research with target applications in both the
near and long term Rolls-Royce has adopted 5, 10 and
20 year visions for the technology it develops. Vision 5
constitutes the low risk technology ready for application
within 5 years. Vision 10 describes the next generation
of technology or capability. Vision 20 describes emerging
or as yet unproven technologies aimed at Rolls-Royces
future generations of products, much of which will be
applied right across the product range in all sectors.
A number of Vision 20 studies are currently exploring
future generations of aircraft architectures that may
provide significant improvements, particularly in areas
of fuel burn, noise and emissions, this includes electric
technologies and distributed propulsion. Rolls-Royce
has also created an extensive range of partnerships and
collaborations around the globe through our network
of 28 University Technology Centres (UTCs). UTCs are
a source of both technology and highly skilled people.
The Group has also applied a similar model in creating
a network of Advanced Manufacturing Research
Centres to develop manufacturing capability. There are
currently 6 operational facilities, the latest having opened
in Crosspointe, Virginia in late 2012. These foster
collaboration between companies at all stages of the
supply chain, from the Original Equipment Manufacturers
(OEMs) to material suppliers, measurement systems
providers and tool manufacturers.
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E-ThRUST Electrical distributed propulsion system concept for lower fuel consumption, fewer emissions and less noise
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ThE VISIon AnD pERSpECTIVE oF An ElECTRICAl DISTRIBUTED pRopUlSIon SySTEm
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EADS Innovation Works and Rolls-Royce, with
Cranfield University as a partner, are jointly
engaged in the Distributed Electrical Aerospace
Propulsion (DEAP) project, which is co-funded
by the Technology Strategy Board (TSB) in the
United Kingdom. The DEAP project researches
key innovative technologies that will enable
improved fuel economy and reduced exhaust gas
and noise emissions for future aircraft designs by
incorporating a Distributed Propulsion (DP) system
architecture.
Innovative propulsion system concepts for future air
vehicle applications are being developed by EADS
Innovation Works, the corporate research and
technology network of EADS, and by Rolls-Royce,
a global provider of integrated power systems and
services to the civil aerospace, defence aerospace,
marine and energy markets. Results of their research
activities support EADS divisions in leveraging
innovation solutions to further improve the efficiency
and environmental performance of commercial aviation.
These efforts are part of the aerospace industrys
research to support its ambitious environmental
protection goals as spelled out in the European
Commissions roadmap report called Flightpath
2050 Europes Vision for Aviation. This report
sets the targets of reducing aircraft CO2 emissions by
75%, along with reductions of nitrous oxides (NOx) by
90% and noise levels by 65%, compared to standards
in the year 2000.
eConcept a future vision Airbus and EADS Innovation Works, along with
other industry players like Rolls-Royce and
Siemens, are exploring different avenues to
find innovative solutions to the challenges the
aviation industry is facing in the future. They are
investigating one such avenue for a 2050 timeframe
a hybrid/electrical distributed propulsion system
as an intermediate but necessary step towards fully
electric propulsion for airliners. Airbus, in its role as
integrator, has taken its concept plane a vision
of aviation in the future and used it to create the
eConcept, a visualisation of the architecture and
configuration of what an aircraft of the future could
look like powered by hybrid/electrical distributed
propulsion. The DEAP project (represented by
the initial E-Thrust configuration) is bringing the
technologies, while Airbus is giving its expertise
as an integrator providing regular inputs and
feedback on the technology developments.
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The configuration with three fans on either side of the fuselage
represents an initial starting point for future optimisations, with the
optimum number of fans to be determined in trade-off studies in the
DEAP project.
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Achieving these goals requires significant
performance improvements in engine technology,
systems architecture and engine/airframe
integration to enable radically more efficient
propulsion systems. Finding viable solutions requires
the pioneering of unconventional aircraft and propulsion
system concepts. In this perspective, propulsion
technologies are continuously being improved through
developments in the fields of energy storage and
conversion, in electrical motors, novel combustion
cycles, ultra-high bypass ratio configurations, along with
hybrid electric/thermodynamic and fully electric systems.
ThE DISTRIBUTED ElECTRICAl AERoSpACE pRopUlSIon (DEAp) pRojECTWith its experience in gas turbine and gas power unit
design, as well as in electric propulsion systems,
Rolls-Royce has for some time been a research partner
of EADS in the fields of energy management and
simulation, electrical machines and superconductivity,
and propulsion system integration. Since 2012,
EADS Innovation Works and Rolls-Royce, with
Cranfield University as a partner (and some testing
subcontracted to Cambridge University), are jointly
engaged in the DEAP project, which researches key
innovative technologies for distributed propulsion
systems. Compared to engines on existing commercial
airliners, such a system will require a much higher level
of integration with the airframe design than that of
todays aircraft.
The DEAP project aims to deliver a preferred electrical
DP system for future aircraft that may provide
a breakthrough and a significant contribution to
mitigating the environmental impact of the projected
increase of air traffic. Rolls-Royce will develop an
optimum electrical system propulsion plant, taking into
consideration speed range, max speed, number of
fan motors, efficiency, etc.; while EADS Innovation
Works (the DEAP project leader) will design the
electrical system and work with Airbus to optimise the
integration of the propulsion system in the airframe.
ThE BEnEFITS oF A DISTRIBUTED pRopUlSIon SySTEm ARChITECTUREFor the E-Thrust concept, distributed propulsion
means that several electrically-powered fans are
distributed in clusters along the wing span, with one
advanced gas power unit providing the electrical
power for six fans and for the re-charging of the
energy storage. The E-Thrust concept can be
described as a serial hybrid propulsion system.
This configuration represents an initial starting point
for future optimisations, with the optimum number of
fans to be determined in trade-off studies in the DEAP
project. Initial study results by Airbus indicate that a
single large gas power unit has advantages over two
or more smaller gas power units. This will give a noise
reduction and allows the filtering of particles in the long
exhaust duct at the back of the engine.
The hybrid DP architecture offers the possibility of
improving overall efficiency by allowing the separate
optimisation of the thermal efficiency of the gas power
unit (producing electrical power) and the propulsive
efficiency of the fans (producing thrust). The hybrid
concept makes it possible to down-size the gas power
unit and to optimize it for cruise. The additional power
required for take-off will be provided by the electric
energy storage.
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A fundamental aspect of optimising the propulsive
efficiency is to increase the bypass ratio beyond
values of 12 achieved by todays most efficient podded
turbofans. For the DP concept, the bypass ratio
must be termed effective bypass ratio, because the
fan airstreams and the core airstream are physically
separated. With DP, values of over 20 in effective
bypass ratios appear achievable, which would lead
to significant reductions in fuel consumption and
emissions. having a number of small, low-power fans
integrated in the airframe instead of a few large wing-
mounted turbofans is also expected to reduce the
total propulsion system noise.
In addition to improving the propulsive efficiency, DP
offers a greater flexibility for the overall aircraft
design that could result in reduced structural weight
and aerodynamic drag, for example, by relaxed
engine-out design constraints leading to a smaller
vertical tail plane, by being able to better distribute the
weight of the propulsion system components and by
re-energising the momentum losses in the boundary
layers that grow over the wing and fuselage causing a
wake (Boundary Layer Ingestion, BLI).
An additional efficiency gain appears possible if this
boundary layer is ingested and accelerated by the
Take-off and & ClimbPower comes from the gas power unit and from the energy storage system to provide the peak power needed during the take-off and climb phase. The energy storage system will be sized to ensure a safe take-off and landing should the gas power unit fail during this phase.
CruiseIn the cruise phase, the gas power unit will provide the cruise power and the power to recharge the energy storage system. In the unlikely event of a failure of the gas power unit, power from the energy storage is available to continue the flight to a safe landing.
FlIGhT pRoFIlE EnERGy mAnAGEmEnT
fans, because it can reduce the aircrafts wake and
hence its drag. however, the implementation of a
boundary-layer ingesting system means that the airflow
into the fans is not uniform; to realize the potential
benefits, the turbo-machinery and in particular, the
fan blades must be able to withstand the associated
unsteady conditions due to the distorted intake
flow. The design of the Rolls-Royce fans is currently
being developed in collaboration with its University
Technology Centre in Cambridge, and is specifically
optimised to deliver the best performance in the
distorted flow conditions that are experienced
in a BLI configuration; its design is supported by
computer analysis as well as reduced-scale testing and
measurements.
For the power levels in the megaWatt range that
are required in an electrical distributed propulsion
network, a new high-voltage superconducting
electrical system has to be designed and validated
to stringent requirements in terms of efficiency.
Such a system must aim to reduce heat being
generated due to alternating current losses in the
superconducting wires, which are enclosed in cables
and surrounded by cryogenic fluid, so that they are
kept at a constant cryogenic temperature for their
best performance. Minimizing such losses is crucial,
as extracting 1 Watt of heat using a cryocooler at 20K
(-252 C) to ambient temperature requires 60 Watts of
electrical power.
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EnABlInG TEChnoloGIES Superconductivity:
A key enabling technology for the DP (hybrid/
distributed propulsion) concept is using
superconductivity in the cables, generators and
motors for the transfer of electrical power from
the gas power unit and energy storage to the
fans. Superconductivity is a quantum mechanical
phenomenon of exactly zero electrical resistance,
which occurs in certain materials when they are
cooled below a critical temperature. It allows the
electrical system components to be much smaller,
lighter and more efficient compared to conventional
copper- and aluminium-based technology. The
necessary cooling can be achieved either by supplying
cryogenic fluids (for example: liquid hydrogen,
liquid helium or liquid nitrogen) from a reservoir,
or by producing the necessary cold temperatures
using a cryocooler a technology used today in
space applications (for example a turbo-Brayton
cryocooler made by Air Liquide for ESA) or in MRI
systems. A side-by-side comparison of copper and
superconducting wires demonstrates the vast size
and weight differences possible with this technology.
Magnesium DiBoride (MgB2) superconducting wires
are made by Columbus Superconductors and used
today, for example, in MRI scanners).
Energy Storage:
Scientists expect new generations of energy
storage systems to exceed energy densities of
1,000 Wh/kg (Watt hours per kilogram) within the
next two decades, more than doubling todays
best performance. Lithium-air batteries are the
most promising solution for the E-Thrust concepts
energy storage requirements. They have a higher
energy density than lithium-ion batteries because of
the lighter cathode, along with the fact that oxygen
is freely available in the environment. Lithium-air
batteries are currently under development and
are not yet commercially available. The E-Thrust
concept is based on the assumption that the
required level of energy density can be achieved
within the 25-year timeframe envisioned for the DP
concept to mature.
Descent/GlidingIn the initial descent phase, no power is provided to the fans, and the gas power unit will be switched off. The aircraft will be a glider and the energy storage system will provide the power for the aircrafts on-board systems.
Descent/WindmillingDuring the second phase of the descent, the fans will be windmilling and produce electrical power to top-up the charge in the energy storage system.
LandingFor the landing phase, the gas power unit is re-started and provides power at a low level for the propulsion system. This is a safety feature to cover a hypothetical loss of power from the energy storage system during this phase.
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The distributed fan propulsion system provides thrust
for the aircraft, replacing conventional turbofan engines.
The large fan diameter and weight of conventional
turbofans limits where they can be located on an
airframe usually under the wing. Their location does
not enable advanced aerodynamic efficiency techniques
to be used, whereas having a number of electrically-
driven fans that are integrated into the airframe
allows for a more aerodynamic overall design.
During descent, the energy-efficient distributed fans are
turned by the airstream and, like wind turbines, they
generate electrical energy which can be stored.
To achieve an integrated distributed fan propulsion
system design that matches the overall airframe
requirements, three key innovative components
are required:
A wake re-energising fan
Structural stator vanes that pass electrical power and cryogenic coolant
A hub-mounted totally superconducting electrical machine
WAKE RE-EnERGISInG FAn As the aircraft flies through the air, it leaves a wake
behind it resulting in drag. The embedded wake
re-energising fan is designed to capture the wake
energy by re-accelerating the complex wake. By
re-energising the wake, the overall aircraft drag is
reduced. The concept uses advanced lightweight
composite fan blades that are designed to maximise
overall propulsive efficiency whilst minimising the
weight of the propulsion system.
DISTRIBUTED FAn pRopUlSIon SySTEm
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STRUCTURAl STAToR VAnES By having an embedded propulsion system, the
conventional turbofan mounting structure is no
longer required thereby saving weight and drag. The
stator section is carefully designed to provide
a row of aerodynamic and structural stator
vanes behind the fan recovering thrust from
the swirling air. The length of the distributed fan,
propulsion system has been designed to be much
shorter than that of a conventional turbofan so that
the centre of gravity is located about the structural
stator vanes. In addition, some of the stator vanes
are designed to accommodate the internal routing
of the superconducting cables to the hub-mounted
superconducting electrical machine.
hUB-moUnTED ToTAlly SUpERConDUCTInG mAChInEThe innovative hub-mounted totally superconducting
electrical machine drives the wake re-energising
fan. Rolls-Royce and EADS Innovation Works, with
Magnifye Ltd and Cambridge University as partners,
are engaged in a Programmable Alternating
current Superconducting Machine (PSAM)
project.The PSAM project researches an innovative
programmable superconducting rotor and innovative
AC superconducting stator.This work is supported in
part by the UK Technology Strategy Board.
The superconducting stator generates a powerful
electro-magnetic field that rotates around the
circumference at a speed directly related to the
frequency of the electrical supply. The superconducting
machine replaces the copper and iron stator structure
of a conventional machine. It is a much more
powerful, lighter and low-loss design incorporating
round-wire high temperature superconducting coils
embedded within a lightweight epoxy structure.
Exploded view showing the hub-mounted totally
superconducting machine
Electromagnetic torque is created by effectively aligning
the rotors magnetic field with the field generated
electro-magnetically within the stator.
The superconducting rotor magnetic field is generated
through the use of bulk superconducting magnets in
a puck form. A superconducting magnetic puck
of this size can, when fully magnetised, generate
extremely high magnetic fields with laboratory testing
demonstrating 17 Tesla a magnetic field capable of
easily levitating a family car. The magnetic pucks are
innovatively magnetised in-situ by the stator to create
a permanent magnet field that can be programmed
to deliver different field strengths thereby improving
controllability.
The superconducting machine design is bi-
directional in that it is equally efficient at driving the
wake re-energising fan to provide aircraft thrust or
being driven by the fan rotating in the airstream to
generate electrical power, which can then be stored
within the airframe.