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Scientific coordination: Dr. Arvind G. Rao
AHEAD : Advanced Hybrid Engines for
Aircraft Development (ACP1-GA-2011-284636)
Level 1: Start 1/10/2011, duration 3 years
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Main Challenges in Civil Aviation
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Future Aviation Fuel
• The long term availability of
fossil fuels cannot be
guaranteed.
• As fossil fuel become scarce,
the price will increase and
alternative fuels may be used.
• In the medium term biofuels
offer an attractive option.
• In the long term, Hydrogen or
Liquid Natural Gas seems the
most attractive option.
2000 2020 2040 2060 2080 2100
Kerosene
Synthetic fuel / GTL/CTL/Biofuels
LNG/ HydrogenA
ircr
aft P
rim
ary
Ene
rgy
Sour
ce
Electric
2000 20202020 20402040 20602060 20802080 21002100
Kerosene
Synthetic fuel / GTL/CTL/Biofuels
LNG/ HydrogenLNG/ HydrogenA
ircr
aft P
rim
ary
Ene
rgy
Sour
ce
Electric
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Cryogenic Fuels (LNG & LH2)
• The mass energy density of
Hydrogen is much higher than
of kerosene, so less fuel is
needed. But the volume is
much higher as well and the
liquid has to be cooled.
• LNG mass density is slightly
better than kerosene but it
also requires special storage
tanks.
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Storage of Cryogenic Fuels
• Storage of LNG and Hydrogen
requires large low temperature
tanks.
• Initial configuration studies
proved to be unattractive as
drag would be increased, thus
increasing the fuel burn.
• New configurations are
needed.
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Storage of Cryogenic fuels in a Multi fuel BWB
LH2/LNG tanks
Kerosene/ Biofuels
• BWB has inherently has extra volume which can be used to
accommodate the cylindrical fuel tanks
• This novel idea of multi fuel BWB is unique which optimizes
the usage of space in a BWB
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• LNG/ LH2 Main Combustor
• Kerosene/ Biofuel Secondary Flameless
Combustor
• Bleed cooling by LH2
• Counter rotating shrouded fans
• Higher Specific Thrust
• Low Installation Penalty
Next generation hybrid engine
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WP1: Conceptual Configuration
Design
WP2: Dual Hybrid combustion system
WP3: Environmental Assessment and Integration
WP4.2: Dissemination
WP4.1: M
anagement
Concept
Technical Solutions
Assessment and Final Configuration
Outreach
Overview of the workpackage structure
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Multi Fuel Blended Wing Body Design
The main task in this WP is to do the conceptual
design of the multi-fuel blended wing body aircraft
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Optimization procedure – Modules
Preliminary design
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Novel Configuration
Multi fuel Blended Wing Body
• TU Delft proposes a Blended
Wing Body configuration
combined with a slender wing
for a very efficient new aircraft
that would replace the Boeing
777 or Airbus 340.
• It incorporates 3 fuel tanks
without substantial drag
penalty.
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Preliminary design
L/D = 24.2
CL = 0.305
CDO = 0.0018
Sref = 900 m2
Results – Aerodynamics
L
D
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Preliminary design
Materials: Carbon Fiber Reinforced
Polymer
Main structure
• Elliptical frames
• Ribs
• Bulkheads
Results – Structures (1)
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Preliminary design
Stability:
• Canards
• Winglets
Control:
• Variable camber canard
• Elevons
• Winglet rudders
Results – Stability and Control
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Preliminary design
New-BWB
Wo 242,800 kg
MTOW 237,970 kg
OEW 122,220 kg
W/S 265.04
(T/W)TO 0.21
TTO 527,810 N
Tcruise 98,195 N
Results – Weight breakdown
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The Bleed Cooling system
The main task of this task is to design a cooling
system to cool the bleed air with the cryogenic
fuel.
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17
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
Stator cooling Heat exchanger in
duct
Colder turbine cooling
bleed
Airco system link
Reduction in fuel consumptionIncrease in Specific Thrust
Performance overview for all studied cycle
Van Dijk, I.P.,Rao, G.A . and Buijtenen, J.P, “A Novel Technique of Using LH2 in Gas Turbine
Engines”, ISABE 2009, Sept 7-11, Montreal, ISABE 2009-1165
Use of Cryogenic fuel as a heat sink
Using the cryogenic fuel to cool the bleed air is the best way of
improving the thermal efficiency of a turbofan engine
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Aim and objectives
The specific objectives of this work package are to:
• To study and analyze suitable techniques /
methodology that could be used for cooling the
bleed air by using LH2
• Preliminary design of the heat exchange system
between the bleed air and LH2
• To perform the sizing of the various components within the
hybrid engine in order to obtain the approximate
dimensions of the hybrid engine.
• To estimate the overall weight of the hybrid engine
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AHEAD project based on baseline engine geometry:
Position of designed heat exchangers on PW4056 engine: LH2 Storage
Designed
Heat Exchangers
LH2 FMM
H2 Combustor
Inter Turbine Flameless
Combustor
Design of the cryogenic fuel to air heat exchanger
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Project development tree: Basic model
Rejected due to
high stress between
compartments
Rejected due to
high stress between
compartments
Rejected due to
high stress between
compartments and
complexity of the
construction
Rejected due to
high stress in bends
Rejected due to
high stress between
compartments and
shape of channel flow
Rejected due to
shape of channel flow
Accepted model
Design of the cryogenic fuel to air heat exchanger
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The hydrogen combustion chamber
The aim of this task is to design the primary
combustor for the hybrid engine using hydrogen as
fuel.
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• Axial injection controlled by mass flow meter
• Impact of axial injection:
• Increases axial velocity at outlet
• Downstream shift of central recirculation zone
Increasing axial injection ( in % )
0 7.5 12
Axial Injection - PIV in Water Tunnel
totax VV /
→ desired flow field
for
=12% totax VV /
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Combustion Test Rig
Gas-fired tests with 100% hydrogen with axial injection on the
TUB combustion test trig
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• Moveable Block (MB)
burner:
• Large mixing length
Lm=170mm
• Pressure loss > 10%
• New burner:
• Reduced mixing length
• Long = 100mm
• Short = 80mm
• Pressure loss 3-6%
Lm=170mm
Lm=80mm
Air
Air
Fuel
Fuel
New Burner – Reduced Dimensions
Approaching an Applicable Design
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• Atmospheric conditions: new burner exhibits wide operational
range without any flashback occurance
Gas Fired Tests: Stability Map
0
0,2
0,4
0,6
0,8
1
1,2
0 100 200 300 400 500
Eq
uiv
ale
nce
Ra
tio
φ
Tpreheat
Operability range of new burner (u0=35-120 m/s)
HP,
m=130kg/h,S=0.9, 8.8mm,
longMT
HP LBO,
m=130kg/h,S=0.9, 8.8mm,
longMT
No flashback
Not tested
Lean blow out
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• NOx emissions increase with inlet temperature Tin
• Below 20 ppm for all Tin at design equivalence ratio of φ≈0.4-0.55
NOx emissions: Inlet Temperature (Tin)
Tin↑
S=0.9 and
long mixing
tube
180°C
350°C
40°C
430°C
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The Inter Turbine Flameless
Combustion Chamber
The main aim of this task is to design and validate
the secondary inter-turbine flameless combustion
chamber for the AHEAD hybrid engine
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Different Combustion Regimes
Flameless combustion
CHARACTERISTICS
• Recirculation of combustion products at high
temperature (> 1000°C)
• Reduced oxygen concentration in the
reactants
• Highly transparent flame with low acoustic
oscillation
• Distributed combustion zone
• Uniform temperature distribution
• Reduced temperature peaks
• Low adiabatic flame temperature
• High concentration of CO2 & H2O
• Lower Damköhler number
• Low NOx and CO emission
Comparison between a conventional combustion and Flameless Combustion (Wünning and Wünning, 2003)
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Evaluated combustor configurations for the Inter
Turbine Flameless combustion Chamber
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Slotted- recirculated ultra lean combustor version #2
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CFD for liquid fuel injection
Left picture shows
more significant
evaporation
process
Droplet evolution for two different injection points
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Climate Impact Assessment of the
Multi-Fuel BWB Aircraft
The primary aim of this task is to analyse the effect
of changing aircraft emissions on the global climate
due to the use of multi-fuel BWB with hybrid
engine
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0.031
0.074
Climate impact of current air traffic (2005)
Lee et al., 2010
updated with Burkhardt&Kärcher, 2011 (for 2002 air traffic)
• Main contributors:
• Contrails
• CO2
• NOx
• 3.5-5.0% of warming
• attributed to air traffic
ACARE, 2008
The findings of the IPCC
point very clearly to the
need to do something but
there are areas of detail
where more understanding
is needed.
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Global climate impact of contrail cirrus
Change in climate impact of contrail
cirrus
Change in formation
conditions (aircraft
related) Change in soot emissions
Change in coverage and microphysical properties of
contrail cirrus
Change in flight
level
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Change in formation conditions II
Implications for contrail formation (2)
AHEAD BWBs will produce contrails in a deeper
atmospheric layer than conventional aircraft because the
threshold temperatures are higher (i.e. formation starts at
lower altitude).
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upward shift - base case
downward shift - base case
Changes in contrail cirrus RF due to changes in flight level
- decrease of RF in mid latitudes,
- increase in tropics/subtropics,
- globally +4 mW/m2 (~9%)
- increase of RF in mid latitudes,
-decrease in tropics/subtropics,
- globally -6 mW/m2 (~13%)
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Change in contrail cirrus radiative
forcing due to a replacement of
conventional planes by LH2 planes
and an increase in flight level by
about 2000m (LH2up3 --
conventional). Contrail cirrus
radiative forcing strongly increased
(factor 1.5) particularly south of 45°N.
Change in contrail cirrus radiative
forcing due to a shift in flight level
of LH2 planes by ~2000m (LH2up3
– LH2). Contrail cirrus radiative
forcing nearly everywhere
decreased.
LH2 version of AHEAD aircraft:
Contrail cirrus radiative forcing - change in formation
conditions + shift of flight level by ~ 2000m
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Change in contrail cirrus radiative
forcing due to a replacement of
conventional planes by LNG planes
and an increase in flight level by
about 2000m (LNGup3 --
conventional). Contrail cirrus
radiative forcing increased (factor 1.4) particularly south of 45°N
relative to conventional air traffic.
Increases smaller than for LH2
planes.
Change in contrail cirrus radiative
forcing due to a shift in flight level
of LNG planes by ~2000m (LNGup3
– LNG). Contrail cirrus radiative
forcing reduced in most places.
LNG version of AHEAD aircraft:
Contrail cirrus radiative forcing - change in formation conditions + shift of flight level by ~ 2000m
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Hybrid Engine Performance
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Ambient Condition
HP Compressor
HP Turbine
Combustor
Nozzle
Cooling
Inter burner
LP Turbine
Inlet
Mixer
Fan & Booster
Pt, Tt
Cp, gamma, R
Gas Composition
Gas Properties
Pt, Tt
Pt, Tt
Pt, Tt
Pt, Tt
Pt, Tt
Pt, Tt
Pt, Tt
Gas Molar Fraction
Tt
Air Properties
Air Properties
Cp, gamma, R
Cp, gamma, R
Tt
Tt
Gas Composition
Gas Properties
Gas Molar Fraction
Tt
Gas Composition
Gas Properties
TtGas Molar Fraction
Cp, gamma, R
Cp, gamma, R Gas Composition
Gas Properties
Gas Molar Fraction
Cp, gamma, R
Pt, Tt
Gas Composition
Gas Properties
Tt
Cp, gamma, R
Gas Molar Fraction
Engine Performance
Core/bypass
In house
Thermodynamic
Model
The model was
validated with GSP
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The Hybrid Engine Model in GSP
Inter-stage
Turbine Burner
Main Combustion
Chamber
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Comparison of hybrid engine with GE90-94B
SFC
CO2
SFC
ST
SEC
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Comparison of hybrid engine with PW4056
SFC
CO2
ST
SEC
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Conclusion
Comparison with B777-200ER (1)
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Conclusion
Comparison with B777-200ER (2)
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CO2 Emission
range 14000 km
Aircraft
Reduction
(%)
KgCO2/(km*k
g) Payload (kg) Passengers
kgCO2/(Pas
senger*km)
B777 65.41 0.0014189 22478 186 0.172
A330 89.267 0.0045728 5737.1 48 0.554
B787 42.913 0.00085974 28985 239 0.104
BWB 0 0.0004908 36400 300 0.059
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The AHEAD Aircraft
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Advanced Hybrid Engines for Aircraft
Development
AHEAD
Delft University of Technology
WSK PZL-Rzeszow S.A
Technical University of Berlin
DLR, IPA
Israel Institute of Technology-
Technion
Ad Cuenta b.v.
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Dr. Arvind Gangoli Rao
Delft University of Technology
Flight Performance and Propulsion
T: +31 (0)15 27 83833
Kluyverweg 1
2629HS Delft
The Netherlands
www.ahead-euproject.eu
Contact
This project receives funding from the European Union's Seventh Framework Programme
under grant agreement nr 284636