This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

FUNDAMENTALS ON PROPULSION SYSTEMS EFFICIENCIESFORUM-AE CO2 WORKSHOP – REIMS – 10-11TH MAY 2017

Nicolas TANTOTSafran Aircraft Engines, Future concepts architect YYYA

nicolas.tantot@safrangroup.com

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Improve powerplant system integration into airframe

Improve energy management (propulsive and non propulsive) on the whole mission

Foreword : The layers of efficiency

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 2

Improve powerplantefficiency (thermopropulsive efficiency)

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Thermopropulsive efficiency

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 3

Improving energy generation (propulsive and non propulsive) on the whole missionImproving powerplant system integration into airframe

Improving powerplant efficiency

Thermal efficiency

Propulsive efficiency

Thermopropulsive efficiencyfuel

aircraftthp PW

PW

1

.

11

OPRkth

in

outpr

VV

1

2

Coreefficiency

Transfer efficiency

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.3 0.4 0.5 0.6 0.7 0.8 0.9

Core efficiency (‐)

Propulsive x Transfer efficiency (‐)

Overall (thermopropulsive) efficiency

0.3 0.4 0.5 0.6(Carnot efficiency ~ 0.87)

TurbopropRegional turbofanBusiness jetsShort medium range turbofan/open rotorLong range turbofan

Challenges on core

technoloy

Challenges on core

technoloy Improving propulsive efficiency, increasing challenge on integration

Improving propulsive efficiency, increasing challenge on integration

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Increasing OPR results in better core and thermal efficiency …

Improve thermal efficiency – High OPR engine

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

0.5

0.55

0.6

0.65

0.7

0.75

0 10 20 30 40 50 60

Overall Pressure Ratio

Ther

mal

effi

cien

cy

OPR 45 50Thermal efficiency ~ + 1 pt

At constant component technology level

4

Propulsive efficiency

Thermopropulsive efficiency

Coreefficiency

Transfer efficiency

Thermal efficiency

… at the expense of increasing technology constraints : Core size decrease threats on HP core feasibility and efficiency,LP shaft integration T3 increase need for advanced materials for last HPC stages Increased compressor stage count weight, length, operability, dynamics Hotter air offtakes detrimental to HPT cooling effectiveness

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

GasTurb 9.0

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

[K]

0 .2 .4 .6 .8 1 1.2 1.4 1.6Entropy [kJ/(kg K)]

0 221

2425

3

441

42

44

495

8

13 18

s18

Improve thermal efficiency : modify cycle – Intercooled engines

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

2 possible sizing strategies: Same T3 as non-intercooled engine OPR benefit SFC benefit through thermal efficiency increase Same OPR as non-intercooled engine lower T3 lower NOx emissions

0

0

0

0

100 k

200 k 300 k 400 k 500 k

Pso =0 2

21 25

3

13 18

s18

Same T3 higher P3

100 k

200 k 300 k 400 k 500 k

Pso =0 2

21 25

3

13 18

s18

Same P3 lower T3

Heat exchanger (“Intercooler”) between core flow and bypass flow compression cooling, at

constant pressure

Heat exchanger (“Intercooler”) between core flow and bypass flow compression cooling, at

constant pressure

5

LPC

FanLPTHPT

Combustor

HPC

Gearbox

Intercooler

Significant impact on integration into

powerplant

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Improve thermal efficiency : modify burner operation

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

Compound Cycle Engine

Pulse Detonation Combustor

Deflagration at constant volume (Humphrey cycle)

Detonation

Rotating piston (Wankel type)

ContinuousRotating

DetonationWave Engine

6

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Decreasing FPR (Fan Pressure Ratio) :increasing propulsive efficiency (and increasing Bypass Ratio)

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

% usefulpropu

lsive pow

er lost

Bypass Ratio (BPR)

Contributors to losses (excluding core)

Improving propulsive efficiency : decreasing fan pressure ratio increasing BPR

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 7

Propulsive efficiency

Thermopropulsive efficiency

Coreefficiency

Transfer efficiency

Thermal efficiency

Propulsive efficiency losses

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Fan losses (isentropic efficiency)LPT eff (0.945)

P18Q13 (SOA dep)Scrubs (SOA dep.)

Série6

Propulsive efficiency losses

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

% usefulpropu

lsive pow

er lost

Bypass Ratio (BPR)

Contributors to losses (excluding core)

Improving propulsive efficiency through BPR increase

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

SFC decrease is very slow beyond BPR 20

BPR 16 BPR 30 : - 4 % SFC

Fan bypass duct losses show a major and increasing contribution

Warning: paper study not representative of any particular engine/aircraft design.

8

Bypass duct losses (pressure loss, scrubbing drag …)

LPT losses (isentropic efficiency)

Ultra high bypass ratio engine target

SFC

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

LPT eff (0.945)P18Q13 (SOA dep)Scrubs (SOA dep.)

Série6

Propulsive efficiency losses

External drag

Weight (made equivalent to thermopropulsive efficiency)

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

% usefulpropu

lsive pow

er lost

Bypass Ratio (BPR)

Contributors to losses (excluding core)

Improving propulsive efficiency through BPR increase

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

SFC evolution is very slow beyond BPR 20

BPR 16 BPR 30 : -4 % SFC

Fan bypass duct characteristics have major and increasing

contribution to losses with BPR

9

Bypass duct losses (pressure loss, scrubbing drag …)

LPT losses (isentropic efficiency)

Fan losses (isentropic efficiency)

Warning: paper study not representative of any particular engine/aircraft design.

Ultra high bypass ratio engine target

Installation effects linked to drag and weight are key

contributors to losses for ultra high bypass ratio

configurationsFuel burn optimum

(ducted configuration)

SFC

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Powerplant integration challenges and open paths

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 10

Improving energy generation (propulsive and non propulsive) on the whole mission

Improving powerplant system integration into airframe

Installation challenges Aerodynamical benefit for closerairframe / powerplant coupling

Highly efficient high bypass ratio engines result in highdimensions powerplants :

Additional challenge on integration constraints Drag, weight for ducted configurations

© E

NO

VA

L co

nsor

tium

Need for building new boundaries between drag and thrust

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

FPR / propulsive efficiency

External drag

Weight (made equivalent to thermopropulsive efficiency)

0

10

20

30

40

50

60

70

80

90

100

% useful propu

lsive pow

er lost

BPR

Contributors to losses (excluding core) The Open Rotor architecture features :

> Propellers with lower equivalentefficiency than ducted fan

> Mechanical transmission similar to geared turbofan (LPT + gearbox)

> No bypass duct loss> Extreme propulsive efficiency

benefit because of ultra lowpropeller pressure ratio

> Significantly lower external nacelle drag

> Weight equivalent to ~ BPR 20 ducted configuration

Still a significant route to riskmitigation, installation constraints, etc …

Ultra high BPR configurations, unducted

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 14

Sw

itch

from

duct

edtu

rbof

anto

und

ucte

dop

en ro

tor

Fuel burn optimum (ducted configuration)

SFC optimum (ducted configuration)

Bypass duct losses (pressure loss, scrubbing drag …)

LPT losses (isentropic efficiency)Fan or Propeller losses (isentropic efficiency)

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A way to decrease inlet speed : fuselage boundary layer ingestion

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 15

1

2

3

Legacyconfiguration

Legacyconfiguration

Boundary Layer Ingestion

configuration

Boundary Layer Ingestion

configuration

Lower inlet speed : improvedthermopropulsive efficiency

p

Fuselage wake (momentum deficit) iscompensated by engine thrust, at the

same spanwise location

Lower absolute exhaust speed lower jet noise

(courtesy : Bauhaus Luftfahrt)

FHVVSFC

thp .0

Aircraft fuselage

Thermopropulsive efficiency

Fuel heatingvalue

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Rear fuselage semi-buried engine installation enabling fuselage boundary layer ingestion

BLI engine configuration – Semi-buried installation option

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies

Additional advantages (on top of BLI effect): Reduced external drag (part of the nacelle is not a wetted surface anymore) Reduced pylon weight (almost no pylon left)

Challenges : BLI thickness lower than fan radius strong fan rotor distorsion Water and ice ingestion dripping from fuselage to engine Unusual thrust/drag bookkeeping affects commercial boundaries betweenairframer and propulsion system maker

Additional advantages (on top of BLI effect): Reduced external drag (part of the nacelle is not a wetted surface anymore) Reduced pylon weight (almost no pylon left)

Challenges : BLI thickness lower than fan radius strong fan rotor distorsion Water and ice ingestion dripping from fuselage to engine Unusual thrust/drag bookkeeping affects commercial boundaries betweenairframer and propulsion system maker

16

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Overall propulsive and non propulsive energy management

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 17

Improve energy management (propulsive and non propulsive) on the whole mission

A single powerplant makes it all …

0

5

10

15

20

25

30

35

40

Take-off Climb Cruise

Pro

puls

ive

pow

er (M

W)

200 % variation

< 5 % mission time > 50 % mission time

Various energy sources management and coupling, as well as distribution of functions over the wholeairframe, can bring significant energy savings

Use of electricity Hybridization

Pressurized air

Mechanical power

Single primaryenergy source

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Hybridization / electrification design space

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 18

Propulsion degree of electrification (through

distribution)

Primary energysource

degree of electrification

100 % fuel powered

100 % electrical powered

Hybridization area

Power source

100 % mechanical

drive

100 % electrical

drive

Hybrid drivearea

Energystoragedensity

High power energytransmission

feasibility

Optimized airframe/propulsion integration

Lower CO2 emissions

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Which configuration for future aircraft platform ?

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 19

This document and the information contained are Safran property. They shall neither be copied nor disclosed to third parties without prior written authorization from Safran.

Thank you for your attention

YYYA / NT – FORUM-AE CO2 Workshop Reims – 10-11th May 2017 – Fundamentals on propulsion systems efficiencies 20