Gas turbine Combustion Modelling Lean combustion and fuels · Gas turbine Combustion Modelling Lean...

© 2012 Rolls-Royce Deutschland Ltd & Co KG

The information in this document is the property of Rolls-Royce Deutschland Ltd & Co KG and may not be copied or communicated to a third

party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce Deutschland Ltd &

Co KG.

This information is given in good faith based upon the latest information available to Rolls-Royce Deutschland Ltd & Co KG, no warranty or

representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding

upon Rolls-Royce Deutschland Ltd & Co KG or any of its subsidiary or associated companies.

©2012 Rolls-Royce Group

The information in this document is the property of Rolls-Royce Group and may not be copied or communicated to a third party, or used for any

purpose other than that for which it is supplied without the express written consent of Rolls-Royce Group.

This information is given in good faith based upon the latest information available to Rolls-Royce Group, no warranty or representation is given

concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce Group or any

of its subsidiary or associated companies.

Tuesday, 20 December 2018, Sydney

Gas turbine Combustion

Modelling

Lean combustion and fuels

Dr. Ir. Ruud Eggels

and contributions of Dr. Thomas Doerr

Rolls-Royce Deutschland Ltd & co KG

Eschenweg 11

Dahlewitz-Berlin

15827 Blankenfelde-Mahlow

Germany

Objectives of this presentation

Overview of Lecture:

Gas turbine combustors performance

Emissions of aero gas turbines

CFD in aero combustion design

Alternative fuels in aero-space

Rolls-Royce proprietary information - private

1-3 3

Combustion Chamber

Aero-engine Architecture – RR Trent

Rolls-Royce proprietary data

HC,is HC

HT,is

HT

30

40

heat release q = cP(TT,40–TT,30)/hcomb

‚The Job‘

C12.5H24 + 18.5 O2 + 69.6 N2 12.5 CO2 + 12 H2O + 69.6 N2

1 kg fuel is burnt to 3.16 kg CO2 and 1.29 kg H20

‚The Challenge‘

Fundamental problem:

Average turbomachinery through flow > 150 m/sec

Burning velocity of kerosene in air ~ 5 to 9 m/sec

Required range of AFRs 35 ~ 150

Stable burning AFR range 4 ~ 30

Air-to-Fuel-Ratio:

Equivalence Ratio:

fuel

air

m

mAFR

30,

AFR

AFR tricstoichiome

Aero-engine Emissions –

Typical sub-sonic cruise emissions

Fuel C12.5H24 +S

Air

N2 + O2

Engine mass flow

percentage

(Jet A-1)

N2

75.2%

O2 16.3%

CO2

72%

H2O

27.6%

Combustion

products

8.5%

SOx

~ 0.02%

NOx

84%

CO 11.8%

UHC

4% Soot 0.1%

Pollutants

0.4 %

1-7

Efficiency corrected to different AFRs

99,0

99,1

99,2

99,3

99,4

99,5

99,6

99,7

99,8

99,9

100,0

0,00 0,01 0,02 0,03 0,04 0,05 0,06Loading theta [-]

Co

mb

. e

ffic

ien

cy [

-]

AFR 30

AFR 40

AFR 50

AFR 75

AFR100

Combustion Efficiency –

Combustor Loading Parameter for annular combustors

correlation for BR700 combustor

)(),(),(

10)(

3030

530

300/308.130

KTpsipfeetV

w

Vepimp

CC

CCKT

We control this !!!

AFR

operating line idle

take-off

Loading Theta

1-8

Stability Limits –

Ignition and Extinction

Combustor Operability Limits –

Influence of pressure

on stability/extinction on ignition

Ignition loops

Wc

8 psi 6 psi 4 psi

massflow

CAEP/2 superseding CAEP/1 on 1st Jan 1996


with ~16% reduction for NOx at OPR=30





CAEP/10 will follow on 1st Jan 2020

Non-Volatile Particulate Matter (nvPM ) will be regulated (mass

and numbers)

Emissions Legislation –

NOx Stringency

UHCCOx

NOj

Fji

EIi

time

ii

flowfuelFjP

D

,,

/))(4

1

(/)(


ICAO Landing-Take-Off (LTO)- Cycle

e.g. for

one engine tested f (NOx) = 0.8627

two engines tested f (NOx) = 0.9094

UHCCONOj

jfFjDFjD

x

measPcharP

,,

)(//)(/)(


Determination of Emissions Margins vs Legislation

UHCCONOj

FjEItimeflowfuelFjD

x

ii

i

iP

,,

/))((/)(4

1

Calculate characteristic value from measured value for Dp/Foo (factor

for engine scatter)

The characteristic value is then compared to the legislative limits for

emissions, which is depending on engine pressure ratio (OPR) and

rated thrust (Foo)

4-13


ICAO Emissions Data Sheet


DpNOx/Foo of aero-engines in comparison to legislation

ICAO Emission Limits for engines above FN 20000 lbf ( 89 kN)

CAEP/2

CAEP/4

CAEP/6

CAEP/8

0

20

40

60

80

100

120

10 15 20 25 30 35 40 45 50

Overall Pressure Ratio

ICA

O L

TO

Dp

NO

x/F

oo

[g

/kN

]

RR

RRD

RRC

Pratt & Whitney Aircraft Group

International Aero Engines

General Electric

CFM International

ACARE target 2020: 40% CAEP/2

Low Emissions Requirements –

Further Drivers

Local landing charges at some European airports

(additional charges for emissions), others may follow

ACARE targets for CO2 and NOx

Flexibility for Future fuels

synthetic fuels, ‚bio‘-fuels; current and new combustor

technologies must be capable burning future fuels while

maintaining operability and emission levels

Low Emissions Requirements –

ACARE targets for CO2 and NOx for Aviation Emissions In January 2001 EU‘s ‚Advisory Council for Aeronautics Research

in Europe‘ set emission reduction targets for 2020 with

CO2 reduction of 50% and

NOx reduction of 80%

The reduction targets comprise aircraft, engine and air traffic

management improvements.

Flightpath 2050 environmental goals

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.700

0.725

0.975

1.000

0.950

0.925

0.900

0.875

0.825

0.850

0.800

0.775

0.750

0.4

0.425

0.450

0.475

0.500

0.525

0.550

0.575

0.600

0.625

Current High

Bypass ratio

Engines

Approaching

Theoretical

Limit, of

Propulsive

Efficiency

Approaching

Theoretical Limit of

thermal efficiency

Theoretical SFC Improvements S

pe

cific

Fue

l C

on

su

mption lb

/hr

/ lb

f @

0.8

Mn

Propulsive

Efficiency

Thermal

“Cycle”

Efficiency

Higher Pressures

Temperatures, Efficiencies

Novel Core Systems

Higher bypass ratios

Novel LP Systems

Emissions:

NOx

Smoke / PMs

CO

UHC

Temperature

Profile

Weak Extinction

Stability

Pressure Loss

Efficiency

Weight

Length Cost

Cold Start Comb. Instabilities

Altitude Relight

Cooling /

Durability

Aero-Engine Combustor Requirements 19

Technology Readiness Staircase – Rich Burn Improvement 20

UTC Loughborough

Combustor CFD Modelling of aero combustors

Requirements:

Short turn around times, easy to use

Support understanding of flow and combustion processes

prediction of combustor exit temperature and velocity profiles

prediction combustor wall temperatures and heat transfer

prediction of NOx, CO, UHC and soot emissions

prediction of combustion efficiency

optimisation process of combustor and fuel injector configurations

CFD in aero combustor design

Challenges:

• Complex geometries

• Complex physics

• Flow field (high swirl, recirculation, jet mixing)

• Liquid fuel spray (2-phase flow, atomisation)

• Combustion (diffusion flames, premixed)

• Large range of length scales:

- Size of effusion cooling holes < 1mm, combustor > 0.3m

- thermal boundary layer < 0.1 mm

• Large range of time scales:

- Time-scales of heat transfer is in order of 1-10 s

- Typical flow through time scale 1ms

- Typical turbulent time scale: 1μs

Not all details can be resolved

Rolls-Royce Combustion CFD code

In-house CFD code PRECISE-UNS

Both Incompressible & compressible

unstructured meshes

RANS/URANS: k-epsilon turbulence models, RSM

LES & RANS capability in same code

Different 2nd order discretisation schemes

Different solvers Hypre multi-grid solvers, AGMG …

Langrangian spray model

Combustion models:

Global chemistry, flamelets, FGM, detailed chemistry

Combustion chemistry interaction modelling

EBU, Presumed PDF, stochastic field PDF

Parallelised using MPI

Heat release modelling

When applying Flamelet Generated Manifolds

Heat release loss options:

a) Using a FGM table for one enthalpy, correct temperature by:

T = TFGM + (H - HFGM) / Cp

b) FGM table for a range of enthalpies:

Different unburned mixture temperature

By using burning stabilised flames

In gas turbines

• The heat loss is limited: no nett heat release through walls

• The air temperature is in the range of 800-1000 K

For most application option (a) is sufficient

2

4

Modelling of combustion

Flamelet Generated Manifolds & Heat Loss

• Within the NGV, both the enthalpy and pressure are not constant

• An additional control variable for the pressure would make the look-

up table too large

• Therefore, isotropic expansion in the NGV is assumed:

Texit / Tref = ( P / Pref ) (γ-1/γ) ), with γ the heat capacity ratio

• An iterative process is required to compute burned mixture

temperature:

The mixture composition depends on the temperature, and the

equilibrium temperature depends on the mixture composition

2

5

Temperature Combustor and high pressure turbine

Overview

Combustor design

Emissions

CFD approach

Validation of CFD

Application to aero-engine gas turbines

Conventional combustion systems

Lean combustion systems

The way forward

Validation of combustion CFD

Validation against small scale well known test cases, for which detailed validation data is available

Sandia Flame D

Generic test cases, more realistic for gas turbine combustion, some experimental data available

Generic combustor

Full combustion system

Application to real gas turbine combustors, limited validation data available

Rich burn combustors

Lean burn combustors



Sandia Flame D


Generic combustor


Application to real gas turbine combustors, very limited validation data available



Validation data: Sandia Flame D

11/10/11

Flame D LES Results

Experiment Mean Temperature Instantaneous temperature

11/10/11

Flame D LES Results

Velocities

Temperature



Sandia Flame D


Generic combustor





-30

-20

-10

0

10

20

30

40

50

60

-30 -20 -10 0 10 20 30

r

Axia

l V

elo

city

Uax (10mm) exp. LDA

Uax (10mm) RANS

Uax (10mm) LES ext.

-20

-10

0

10

20

30

40

50

60

70

-0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025

r [m]

Axia

l V

elo

city [

m/s

]

Uax-Exp 1mm

Uax-RANS 1mm

Uax LES refined (1mm)

Generic combustor: Burner exit

10 mm above burner

Model includes swirlers

Pressure field

• Improved turbulence modelling and

unsteady phenomena

• Velocity better captured by LES

• Vortex core structure resolved.

Generic combustor

600

800

1000

1200

1400

1600

1800

2000

2200

-30 -25 -20 -15 -10 -5 0 5Radius

Tem

pera

ture

Temp FGM 10mm

Temp FGM 14 mm

Temp FGM 18 mm

Temp FGM 22mm

TEMP FGM 26mm

T [K] exp. 10mm

T [K] exp. 14mm

T [K] exp. 18mm

T [K] exp. 22mm

T [K] exp. 26mm

Computed

temperature

Internal data available for generic combustor

• which has typical features of aero engine combustor

• representative operating conditions

Quite good agreement between CFD & Experiments



Sandia Flame D


Generic combustor

Full combustion system (cold flow)




36

KIAI-ITR4-KIT- 22-23/09/2011

Modelling isothermal aero dynamics

36

Realistic aero engine geometry

Including pre-diffusor, annuli and full fuel injector

Challenge

Modelling aero dynamics of pre-diffusor and dump gap

Experimental velocity data available (measured at LU)

37

KIAI-ITR4-KIT- 22-23/09/2011

Applied grid

Hexa dominant

Grid (12.5 M cells)

38

KIAI-ITR4-KIT- 22-23/09/2011

Boundary conditions

Axial and tangential velocity at OGV inlet: applied

measured profiles

Axial velocity Swirl velocity Measured axial velocity

39

KIAI-ITR4-KIT- 22-23/09/2011

Velocities

RANS

results

Velocity results

KIAI-ITR4-KIT- 22-23/09/2011

40

URANS, time avaraged

Small changes between RANS and URANS. LES shows

different angle of outer swirler flow

LES, time averaged

41

KIAI-ITR4-KIT- 22-23/09/2011

Results at OGV exit

Steady RANS, LES and measurements

Large scale effects captured, but considerable local

differences

CFD results combustion system modelling

42

KIAI-ITR4-KIT- 22-23/09/2011

CFD results combustion system modelling

OGV exit: turbulent kinetic energy

CFD (RANS) Measured

KIAI-ITR4-KIT- 22-23/09/2011

Results at diffuser exit

Measured

Total velocity

CFD

Mean velocity structure captured, however:

• refined grids required

• results strongly dependent on pre-diffusor inlet boundary condition, which is

inherent unsteady (compressor aerodynamics)

Full combustor system modelling

Velocity field Temperature field

As many details of the

geometry is taken into

account, while these may

have an impact on the

results

Full combustion system traverse

Predicted combustor exit temperature within measured uncertainty

Prediction of NOx and CO emissions

NOx and CO trends can be predicted reasonably well

NOx predictions against rig data


• Very good prediction of NOx trend.

• However, absolute value is off by a factor of 3.

• CFD (LES) results compared with LII soot

measurement data from EDS rig DLR Cologne

using aero engine injector.

• 130k time steps

• FGM combustion model

• Modified IC (Lindstedt) two-equation soot model

• Good quantitative agreement of predicted soot

with measured data within primary zone

• However measurements

are performed with

aromatic free fuel

• Oxidation too slow

4

8

LII (DLR)

Precise-UNS

Soot modelling / EDS Rig DLR Cologne

CTI- Simulations with PRECISE-UNS

Large Eddy Simulation BR710 full annular combustor with NGV

Light-around modelling: temperature and spray evolution after ignition

4

9

Aero Engine Combustor modelling

Combusting CFD application

Rich Quench Lean combustor

Combustor only

Including annuli / part of fuel injector

Full combustor system

Using CFD for combustor development;

optimisation

Lean combustors


Combustor design

More refined combustor design using CFD

Maxim Gessel, UBWM, IMPACT-AE

Combustor port optimisation example

Objective: to improve NOx and soot emissions

By moving and resizing dilution ports

20-50 different configurations have been considered


Combustor port optimisation example

EINOX ~ - 21%

SOOT ~ - 75 %

Torsten Voigt

54 CAD Combustor Development

DLD

CFD optimisation

Full combustor system model

Grids generated using ICEM-CFD and BoXer

RANS, FGM combustion model, NOx and soot

emissions

Parameters modified in the design optimisation

Position of dilution holes

Number of dilution holes

Angle of dilution holes

Optimisation objectives

NOx emissions, ICAO cycle

Soot emissions, ICAO cycle

Temperature traverse, to meet turbines requirement

55

Optimization example, for single row combustor

Variation of the number of mixing holes per row (2 to 5)

Single row combustor

Equally distributed mixing holes on both liner sides

Central port on fuel spray nozzle axis

56

Optimization example

NOx emission results for ICAO cycle:

Significant decrease of EINOx for ICAO100 and ICAO85 with increasing number

of dilution holes

However soot is increasing significantly: additional changes are required to

reduce soot, e.g. fuel injector

With increasing number of dilution holes, distance between holes becomes

smaller leading to mechanical issues

57

Results of CFD optimisation

Results of CFD optimisation:

- Manual driven process

Most interesting

Optimized

geometries

Baseline

configuration

58

Optimised combustor

Reduction in peak temperatures, therefore reduced NOx formation

59

Validation agains Full annular rig testing


• Combustor has been

optimised in relative small

steps using CFD (only)

• Next combustors have been

manufactured FANN test are

performed

• Correlation between CFD

and experimental data are

good

Low Emission Combustion Technologies –

Low emissions approaches:

Rich Burn Combustion

Optimised RQL (Rich burn - Quick quench - Lean burn)

combustion concepts with rapid quenching and reduced

residence times

staged rich burn combustors operating within narrow

stoichiometry limits

Lean Burn Combustion

Lean Direct Injection LDI

Lean Premix Prevaporise LPP, LP(P)

Air Staging – Variable Geometry

Lean Burn Combustion Technology – Principle

4-63

63

Air

60 - 70%

AirStoich 40% 40 - 30%

Lean Burn injector performance dominating combustor characteristic

Premixing with up to 70% of combustor air mass flow within lean burn

injector

RR – Lean Burn Combustion Technology

AirCool

R Q L

Main flame

Pilot flame 10% +20%

AirStoich

AirCool

Conventional (RQL) vs Lean Burn Combustor

+30%


For lean burn combustor, a large percentage (60-80) of the combustor

air flow goes through the fuel injector.

The fuel /air mixing process is very important

Often pre-cessing vortex cores are observed.

Lean burn fuel injector

11/10/11

Lean combustor CFD validation

The Big Optical Single Sector located at DLR Cologne


Lean burn CFD validation

Set-up:

~ 10m Cells

Combusting Large Eddy Simulation

Hybrid Mesh

Hexa cells in core

FGM Combustion model

Liquid kerosene fuel

~ 150k Time steps to achieve good

statistics

Lean burn systems are much more difficult to model:

• Lean combustion: stabilisation through flame propagation

• Combustion is staged: pilot & mean combustion zones

• Much more swirl dominated, associated unsteady behaviour


Lean combustor modelling

- Temperature

Instantaneous

Results

- Velocity

11/10/11

Lean combustor CFD verification: Results

Private - Rolls - Royce Data

Mean Temperature

OH* Temperature

Mean Fuel (C12H23) Mass-fraction

C* spectral response

11/10/11

Lean combustor CFD verification- Results

Axial Velocity PIV (Spray & Seeding)

Mean Axial Velocity LES

A

B

Velocity field behind fuel injector well captured by CFD


A B

Plane A

Axial Velocity

Radius

Radial Velocity

Radius V

elo

cit

y

Averaged ~ 0.04 s Averaged ~ 0.08 s

Lean combustor CFD verification

Velocity field behind fuel injector well captured by LES, but long averaging times are

required.


A B

Plane B

Axial Velocity

Radius

Ve

loc

ity

Radius V

elo

cit

y

Radial Velocity

Lean combustor CFD verification

Long integration time required to get predict pilot velocity correctly

Emissions Modelling: NOx

Lean combustor

Using different injector geometries

Trend predicted reasonably

However, higher accuracy required for

reliable design process

Uncertainties in temperature field and

spray modelling have large effect on

emissions 4

6

8

10

8 12 16 20

Computed EINOx

Me

asu

red

EIN

Ox

Combustor CFD Modelling –

Lean burn combustor exit traverse prediction

14 ·106 grid cells

0 20 40 60 80 100

Duct Height [%]

RT

DF

FANN tes t

CFD

Polynomisch(CFD)Polynomisch

(FANN tes t)

FANN testCFD

full annular test

Radial averaged temperature well

predicted. However, considerable

differences in 2D temperature field

Fuel & Controls System

pilot/main staging

circumferential main staging may be needed

Stability control

Lean burn injector

dominates combustion performance

partially premixing, up to 70% air flow

through fuel injector

internally staged with nested pilot injector

separated pilot and main stage combustion

Combustor

cooling optimised to enable lean operation

and life targets

no mixing ports

Lean Burn Combustion –

RR Lean Burn Technology

0% 20% 40% 60% 80% 100%

%FN

NOx Smoke

ICAO idle ICAO approach ICAO climb ICAO MTO cruise

Pilot only

As Power increases Pilot to Main split reduces

1st staging

point above

idle power

Pilot, all mains

2nd staging

point at mid

power

CO

Pilot, part mains

Staging optimised for

emissions. CO and PM (invisible

smoke) only produced during

transients.

Lean Burn Combustion –Fuel Staging Scenario

N Ox D istribu tion w ith in LTO C ycle

0%

10%

20%

30%

40%

50%

60%

70%

R Q L Lean B urn

%C

AE

P2

7%

30%

85%

100 %

impr. mixing, red. cooling

High power NOx

Lean Burn Combustion –

Impact of pilot stage on total emissions

For low emission lean burn systems the rich pilot zone cause

significant amounts of NOx at low power operating conditions

Further NOx reduction of lean burn systems need to include NOx

reduction measures of piloting devices

77

BOSS/ HBK1 HPSS/ HBK3

Big Optical Single Sector High Pressure Single Sector

Emissions up to 40 bars Emissions up to 20 bars

Non-intrusive measurements, e.g.

PDA droplet characterisation

Chemiluminescence volumetric OH*-

concentration

LIF OH- / fuel concentration

Mie-scattering fuel droplet concentration

PIV 2D velocity field

Method Variables

Test rigs for lean burn injector development

Injectors easily exchangable between

both rigs

HPSS: very robust and reliable, focus:

full scale emission performance*

BOSS: optical access / non-intrusive

measurements, focus: investigation of

detailed flow/ mixing/ combustion

effects, generation of design rules

4-78

78

Lean Burn Injector – Staged Operation at Elevated Pressures

Internally staged lean burn fuel injector

kit of parts with

pressure atomiser

pre-filmer and

discrete jet injection

6bar, 700K, Variation Pilot-Main Fuel Split

100% Pilot

Only

50%

10% 0% Main Only

20%30%

100% Pilot

Only

50%

10% 0% Main Only

20%30%

Take-off emissions in single sector combustor (35 bars, 850K)

Lowest NOx at lowest pilot fuel split

Aerodynamic separation of pilot and

main combustion zones

Main fuel preparation critical for

low emissions at take-off

Laser diagnostics in optical high pressure sector at DLR (20 bars, 850K)

Flame & flow field visualisation

Heat release (OH* chemiluminesence)

Investigation of fuel preparation, pilot and

main interaction, correlation to CFD

Module AFR

V1C7, V1C10, V2C1, V3D3C22: 31bar, 820K

0

5

10

15

20

25

30

35

20 25 30 35 40 45

Module AFR

EIN

Ox

V1C7, 10:90

V1C7, 30:70

V1C10, 10:90

V1C10, 30:70

V2C1, 10:90

V2C1, 30:70

V3D3C22, 5:95

V3D3C22, 20:80

C-B low pilot

C-B high pilot

C-E low pilot

C-E high pilot

C-F low pilot

C-F high pilot

C-G low pilot

C-G high pilot

C-B high pilot split

Lean Burn Injector Performance at Take-Off Condition

97,0

97,5

98,0

98,5

99,0

99,5

100,0

0 20 40 60 80

Pilot Fuel@AFRm=30

eta

CC

%

0

2

4

6

8

10

12

14

EIN

Ox(

g/k

g)

BOSS

HPSS-eta

HPSS-EINOx

Fuel Split (%)

Combustion

Efficiency

[%]

EI(NOx)

[g NOx/ kg Fuel]

Very strong influence of fuel split on NOx

and efficiency

Below 40% main flame is burning lean in a

lifted mode (separated from pilot)

Above 40% pilot/ main flames are merged,

dominated by pilot

Optimal fuel split at this condition for low

NOx and high efficiency: 30-45%

20% Split 40% Split 60% Split

Fuel Splitting Effect (Split = Pilot/ Total Fuel Flow) Cruise Condition (P30 = 9.4 bar,

T30 = 713 K, AFR = 30)

Lean Burn Injector Performance at Cruise Condition

4-81

Spray before ignition

1st burner ignition

2nd burner ignition

SARS – Sub-atmospheric Relight Sector Rig, RR Derby Twin sector – Subatm. Tests for Ignition, Light-across and Efficiency

Pilot only – narrow cone spray

Pilot only – wide cone spray

82

Lean Burn Validation on System Level – Rolls-Royce demonstration of low emission lean burn combustor

module and fuels and control system within real engine

environment on ground and in flight

E3E March 2008 Core 3/2

March/April 2010 Core 3/2b

July/August 2011 Core 3/2c

Juni 2012 Core 3/2d, Rain ingestion testing

Test at ILA Stuttgart, Germany

Trent 1000 - New Technology Demonstrator

ALECSYS – System validation on flying test bed

B747 with mod Trent 1000 engine, planned for 2019

EFE - Feb 2010 Bristol, UK

Low Emission Combustion Technology –

NOx emissions reduction potential

ICAO Emission Limits for engines above FN 20000 lbf ( 89 kN)

ANTLE

E3EII

PW TALON X

CAEP/2

CAEP/4

CAEP/6

CAEP/8

ACARE target 2020: 40%

CAEP/2

0

20

40

60

80

100

120

10 15 20 25 30 35 40 45 50

Overall Pressure Ratio

ICA

O L

TO

Dp

NO

x/F

oo

[g

/kN

]

RR

RRD

RRC

Pratt & Whitney Aircraft Group

International Aero Engines

General Electric

CFM International

GE TAPS Lean Burn

RR Rich Burn

© 2012 Rolls-Royce Deutschland Ltd & Co KG

The information in this document is the property of Rolls-Royce Deutschland Ltd & Co KG and may not be copied or communicated to a third

party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce Deutschland Ltd &

Co KG.

This information is given in good faith based upon the latest information available to Rolls-Royce Deutschland Ltd & Co KG, no warranty or

representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding

upon Rolls-Royce Deutschland Ltd & Co KG or any of its subsidiary or associated companies.

©2012 Rolls-Royce Group

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of its subsidiary or associated companies.

Tuesday, 20 December 2018, Sydney

Gas turbine Combustion

Modelling

Alternative fuels

Dr. Ir. Ruud Eggels

Rolls-Royce Deutschland Ltd & co KG

Eschenweg 11

Dahlewitz-Berlin

15827 Blankenfelde-Mahlow

Germany

Fuel criteria

Safety and operability issues Energy density

Chemical characteristics

Environmental and social issues Fuel lifecycle CO2 emissions

Change in land and water usage

Feedstock competition with food crops

Large-scale commercial production issues Fuel technology maturity level

Production capability and readiness level

Impact of fuel properties

Material

Compatibility

Aromatics, freezing pt.

Acidity, Copper Strip

Certification

All Characteristics

Durability

As Above

Lubricity

Acidity

Safety

Flash Pt., Freezing Pt.

Microsep

Maintenance

Same as Durability

Legacy Hardware

Aromatics, lubricity

Cost of

Ownership

ThermalStab.

Exist. Gum

Sulfur

Future Technology

Specific Heat, Thermal Stab.

Aromatics, Sulfur/polar Materials

System Design

& Materials

All Characteristics

Performance

Heating Value

Density

Flash/Freezing Pts.

Cold Start &

Alt re-light

Flash Pt., Heating Value

Distillation, viscosity

Deposition

(coking)

Thermal stability, Gum,

Distillation

Hot-End Life

Thermal Stability, Acidity

Aromatics, Sulfur

Physical

Properties

Chemical

Properties

Fluid Performance

Prediction

Freezing Pt., viscosity

Distillation, Thermal stability

Emissions

Aromatics, Sulfur

distillation

Growth in Aviation


Ref: Airbus

Eco-Efficient Aviation

Aviation needs to flourish with reduced

environmental impact

Aviation is necessary for development

Facts:

8% Global GDP

2% man made CO2 emissions

Over 40 years the focus on innovation

has lead to

70% reduced aviation fuel

consumption and related CO2

emissions

Targets:

Carbon Neutral growth by 2020

50% CO2 reductions by 2050

compared to 2005

Sustainable Aviation Growth with Environmental targets

Page 88

CO2 Emissions Trends

Ref: ICAO

Background: What’s Required?

• Meet all current safety requirements

• Same Aircraft performance considerations

• Same properties as Aviation Jet-fuel Kerosene

Consistent, thermally stable,

High energy content

Low freezing point, high flash point...

- Freezing point (- 47 °C)

• Meets Jet-fuel specifications

Any new fuel has to meet the above characteristics

Page 90 Ref: Airbus

Background: Short/Medium Term Requirement

• Use existing airport fuel storage

• Common aviation fuel distribution network

• With common piping and transport infrastructure / mechanisms

• Any alternative should be “drop-in”

…..and mixable with fossil fuel

A “Drop-in” solution is required

Page 91 Ref: Airbus

Where we are: What are the Options?

Non-Renewable

(Fossil)

Renewable

Jet Fuel

CTL

GTL

Hydrogenated Biomass Oils

(HBO)

Low energy content per unit volume, Availability,

Infrastructure

Cryogenic Fuels

Ethanol … Fame

Hydrogenated Biomass

BTL

Liquefied Natural Gas

Conventional (“Kerosene”)

Alcohols Bio Esters Synthetic Fuels

10% lower energy

content,

-5°C Freeze point…

35% lower energy content

Liquid Hydrogen

TYPE

BIO- JET

FUELS

* FAME =Fatty Acid Methyl Esters CTL, GTL & BTL =Coal, Gas or Biomass to Liquid

Not all options are suitable for aviation today Page 92

Ref: Airbus

Algae

Jatropha

Salicornia Camelina

Wood waste

Yeast

What are the alternative fuels? Potential sustainable feedstocks

Multi options in different locations

Page 93 Ref: Airbus

Production route for alternative fuels


The supply of large quantities of alternative kerosene within low GHG emissions

is (theoretically) possible by coupling the sectors electricity generation and fuel

markets (without biomass imports).

Ref: DLR

Comparison of CO2 Emissions from alternative fuels

6

8

10

12

14

16

18

20 n-P

i-P

N

DiN

MoArNmoAr

DiAr

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

%

C numberChemical type

n-P

i-P

N

DiN

MoAr

NmoAr

DiAr

Fuel composition example

Typical Jet A-1

Shell Bintulu

GTL fuel

Rolls-Royce joins Air New Zealand and Boeing in renewable fuels study programme Flight evaluation of a renewable bio fuel blended with kerosene fuel source

Part of research programme to understand renewable fuels and potential future applications.

Aircraft – ANZ 747-400, Engine – RB211-524GT – only one engine will use the fuel

Timing –Dec 2008

Fuel analysis shows fuel meets/exceeds current specification technical requirements

50:50 Blend – Jatropha derived SPK (HVO) and std Jet A-1

Therefore is drop-in.

Data gathered throughout the test process will contribute to understanding of the capabilities

and limitations of renewable fuels

After the evaluation, the engine was examined/overhauled prior to returning to service.

Airbus / Shell / Rolls-Royce A380 demo Flight evaluation of a 40% GTL kerosene fuel blended with conventional fuel

Part of research programme to understand renewable fuels and potential future

applications.

Aircraft - Airbus A380 MSN4

Engine - Trent 900 – only one engine used the derived fuel

Timing – 1 Feb 2008

Data gathered throughout the test process reported and contributing to

understanding of the capabilities and limitations of renewable synthetic fuels

GTL Fuel used in A380

GTL fuel manufactured at the Shell Bintulu plant.

This plant produces 14000 barrels of product per day

Plant is tuned to deliver diesel fuel.

For flight test fuel was blended with Jet A1 to produce min SG

from def stan91-91.

Flight from Bristol to Toulouse.

3 Hr flight

1 engine of 4 was fuelled with alternative fuel.

Handling of the engine was carried out at several altitudes.

Altitude relight tests were also performed.

All the testing was successful.

Airbus GTL* Flights

*GTL = Gas To Liquid

Synthetic fuels work and are a precursor for Biofuels

• February 2008 Flight test

~50% GTL

A380 on one out of the four engines

Rolls-Royce engines

• October 2009 First ever commercial revenue

flight

~50% GTL

A340-600 all engines

Rolls-Royce engines

Page 100 Ref: Airbus

Cost of aviation fuels


ECLIF Measurement results




CO and NOX emissions very

similar









ECLIF key conclusions

Alternative jet fuels with lower aromatic content (i.e. higher H

content) produce less soot emissions.

First measurement showing the effect of naphthalene's.

First ground and in-flight emissions measurements with a Fully

Synthetic Jet Fuel (Sasol’s FSJF). .

Synthetic jet fuels yield a decrease in concentration and size of

soot particles.

Ice particles measurements show a definite correlation with soot

emissions characteristics.

First experimental validation of impact of soot particle size on

contrail characteristic (radiative properties).


Summarising

Potential for significant emissions reductions

Depends on feedstock type and cultivation, conversion

process…

Emissions reductions achievable with existing aircraft

Benefits will depend on:

the availability of such fuels and the time profile of their

deployment

their actual lifecycle emissions reduction

Challenges

Decreasing production cost

Investment in feedstock production and conversion facilities

Ensuring a sustainable deployment

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