fundamentals on propulsion systems efficiencies · 2020-07-05 · this document and the information...
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FUNDAMENTALS ON PROPULSION SYSTEMS EFFICIENCIESFORUM-AE CO2 WORKSHOP – REIMS – 10-11TH MAY 2017
Nicolas TANTOTSafran Aircraft Engines, Future concepts architect YYYA
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
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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
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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
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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
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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
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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
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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
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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