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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

E: A.GangoliRao@tudelft.nl

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