a nasa perspective on electric propulsion...
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National Aeronautics and Space Administration 1
National Aeronautics and Space Administration
A NASA PERSPECTIVE ON ELECTRIC PROPULSION TECHNOLOGIES FOR COMMERCIAL AVIATION
Nateri Madavanand James Heidmann,, Cheryl Bowman, Peter KascakAmy Jankovsky, and Ralph Jansen
Advanced Air Transport Technology ProjectNASA Advanced Air Vehicles Program
Workshop on Technology Roadmap for Large Electric MachinesUniversity of Illinois Urbana-ChampaignApril 5-6, 2016
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Background
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NASA Aeronautics Vision for the 21st Century
On Demand Fast
TRANSFORMATIVE
Intelligent Low Carbon
SUSTAINABLE
Safety, NextGenEfficiency, Environment
GLOBAL
A revolution in
sustainable global air
mobility
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Aviation’s Grand Challenge
CO
2E
mis
sion
s
Wit
h Im
prov
emen
t
Additional Technology Advancement
Carbon neutral growth
and Low Carbon FuelsCarbon overlap
By 2050, substantially reduce emissions of carbon and oxides of nitrogen and contain objectionable noise within the airport boundary
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Advanced Air Transport Technology Project
Explore and Develop Technologies and Concepts forImproved Energy Efficiency and Environmental Compatibility forFixed Wing Subsonic Transports
Evolution of Subsonic Transports Transports
1903 1950s1930s 2000s
DC-3 B-787B-707
§ Early stage exploration and initial development of game-changing technologies and concepts
§ Commercial focus, but dual use with military§ Gen N+3 time horizon § Research aligned with two NASA Aeronautics strategic R&T thrusts § Research vision guided by vehicle performance metrics developed for
reducing noise, emissions, and fuel burn
6Advanced Air Transport Technology ProjectAdvanced Air Vehicles Program Analysis based on FAA US operations data provided by Holger Pfaender of Georgia Tech
Fuel Consumption by Aircraft Size Class
40% of fuel use is in 150-210 pax large single aisle class87% of fuel use is in small single-aisle and larger classes ( >100 pax) 13% of fuel use is in regional jet and turboprop classes
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Hybrid-electric propulsion for commercial aviation
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The Case for Hybrid Electric Propulsion
• Lower emissions, lower noise, better energy conservation, and more reliable systems
• Considerable success in development of “all-electric” light GA aircraft and UAVs
• Advanced concept studies commissioned by NASA for the N+3/N+4 generation have identified promising aircraft and propulsion systems
• Industry roadmaps acknowledge need to shift to electric technologies • Creative ideas and technology advances needed to exploit full potential• NASA can help accelerate key technologies in collaboration with other
government agencies, industry, and academia
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Four Cardinal Electric Propulsion Architectures
ParallelHybrid
Fuel Fan
TurbofanElectric Bus
MotorBattery
1 to ManyFans
Electric BusMotor(s)
BatteryAllElectric Turboelectric
Fuel
Turboshaft
Generator
Electric BusDistributed
Fans
Motor
Motor
Series Hybrid
Fuel
Turboshaft
Generator
Electric Bus
Battery
DistributedFans
Motor
Motor
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Lower Carbon Designs: Reduce combustion-based propulsive power (and emissions) using electric motors and/or on-board “clean” energy storage
Distributed Propulsion: Allows effective increase in fan by-pass ratio through distributed propulsors
Boundary Layer Ingestion: Allows propulsion systems to energize boundary layers without distorted flow entering turbine core
Wing Tip Propulsors: Allows energization of wing tip vortices without penalty of small turbomachinery
Hybrid Electric Propulsion Enables Wide Range of Configuration Options
Common Technology Requirement: Increased efficiency and specific power in electric drive systems, thermal management systems, power extraction, and/or energy storage
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NASAN3X
Airbus/Rolls-RoyceeThrust
ESAero ECO-150
Future Turboelectric Aircraft Concepts
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NASA HEP perspective and challenges
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The NASA Perspective• Develop and demonstrate technologies that will revolutionize commercial
transport aircraft propulsion and accelerate development of all-electric aircraft architectures
• Enable radically different propulsion systems that can meet national environmental and fuel burn reduction goals for commercial aircraft
• Focus on future large regional jets and single-aisle twin (Boeing 737-class) aircraft for greatest impact on fuel burn, noise and emissions
• Focus on hybrid-electric technologies since all-electric propulsion for large transports unlikely in N+3 time horizon
• Research horizon is long-term but with periodic spinoff of technologies for introduction in aircraft with more- and all-electric architectures
• Leverage investment in efficiency improvements in the energy sector
• Power system development for terrestrial applications does not adequately address weight or thermal management requirements for aviation applications
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Hybrid Electric Propulsion Technology Projections
5 to 10 MW
• Hybrid electric 50 PAX regional• Turboelectric distributed propulsion 100 PAX regional• All-electric, full-range general aviation
• Hybrid electric 100 PAX regional• Turboelectric distributed propulsion 150 PAX• All electric 50 PAX regional (500 mile range)
• Hybrid electric 150 PAX• Turboelectric 150 PAX
>10 MW
Powe
r Lev
el fo
r Ele
ctric
al P
ropu
lsion
Today 10 Year 20 Year 30 Year 40 Year
Projected Timeframe for Achieving Technology Readiness Level (TRL) 6• Turbo/hybrid electric
distributed propulsion 300 PAX
• All-electric and hybrid-electric general aviation (limited range)
Technologies benefit more electric and all-electric aircraft architectures:
• High-power density electric motors replacing hydraulic actuation
• Electrical component and transmission system weight reduction
kW class
1 to 2 MW class
2 to 5 MW class
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Timeline for Electric Machine ApplicationMachine Size Depends on Electrification Architecture
SuperconductingNon-cryogenic 100 kW 1 MW 3 MW 10 MW 30 MW
19 Seat2 MW Total Propulsive Power
300 Seat60 MW Total Propulsive Power
9 Seat 0.5 MW Total Propulsive Power
50-250 kW Electric Machines
0.1-1 MW Electric Machines
50 Seat Turboprop 3 MW Total Propulsive Power
0.3-6 MW Electric Machines
150 Seat22 MW Total Propulsive Power
1-11 MW Electric Machines
3 -30 MW Electric Machines
Largest Electrical Machine on Aircraft
50 Seat Jet12 MW Total Propulsive Power
150 Seat22 MW Total Propulsive Power
1.5-2.6 MW Electric Machines
0.3-6 MW Electric Machines
Leftsideofeachpowerrangebaristhesmallestmotor thatyields overallaerodynamicefficiencyincreaseforapartiallyelectrifiedairplane
Rightsideisthesizeofageneratorforatwinturboelectricsystemforafully electrifiedairplane
What Technologies are Required?Depends on vehicle size and range
It is a vehicle optimization problem
• Better energy storage opens up more options for distributed propulsion or all-electric
• Better electric machines open up all options • Better power grids are required for anything in the MW level• Better materials and subcomponents enable better electric machines
and power systems• Systems level studies and tests are required to pin down key
performance parameters for each technology
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Hybrid Electric Propulsion Challenges
• Weight• Weight• Heat• Safety• Reliability• Certification
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Gas Turbine Engines… The Past 50 Years
Thrust to Weight
130
120
110
100
90
801940 1960 1980 2000
Engine Noise(cum db’s)
8
6
4
2
01940 1960 1980 2000
0.9
0.8
0.7
0.6
0.5
0.41940 1960 1980 2000
Fuel Efficiency(SFC)
Flight Safety(accidents per MFH)
20
15
10
5
01940 1960 1980 2000
25
90%Improvement 350%
Increase
35 dbDecrease
45%Improvement
From: Dale Carson, GE Aviation (EAA Electric Flight Symposium, July 2011)
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NASA AATT hybrid-electric propulsion research and technology investments
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NASA AATT HEP Technology Investments
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High Efficiency, High Specific Power Electric Machines
• Develop both conventional (near-term) and cryogenic, superconducting (long-term) motors
• Design and test scalable high efficiency and power density (96%, 8 hp/lb) 1 MW non-cryogenic motor for aircraft propulsion in collaboration with
• Ohio State U • U of Illinois, UTRC, Automated Dynamics
• Reduce AC losses and enable thermal management for SC machines: models and measurement techniques, SC wires, flight-weight cryo-coolers
• Design and test fully superconducting electric machine test at 1 MW design level in FY17-18
• Collaboration with Navy, Air Force, Creare, HyperTech, Advanced Magnet Lab, U of FL
• Detailed concept design completed of 12MW fully superconducting machine achieving 25 hp/lb
• Develop materials and manufacturing technologies
Fully superconducting motor
U of Illinois Design
Ohio State U Motor Design
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TRL 2-3 Motor design analysis for 1 MW size predicts performance feasibility
Development Potential for Electric Machines
NRA Contract: TRL 4 Demo by 2018 for 1 MW machine with 13 kWkg (8hp/lb), 96% efficiency (triangle)
Synchronous reluctance motor with SOA materials (open circle), with advanced materials (solid circle)
Interior Permanent Magnet motor with SOA materials (open square), with advanced materials (solid square)
Launchpoint UAV
Industrial Motors
2008 Lexus
Jansen et al., AIAA 2015-3890; Duffy, et al., AIAA 2015-3891
Minimumacceptableelectricdrivesystemperformance
Median
Electrical Machine ProjectionsTechnology Impact on Specific Power for Non-Superconducting Machines
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Flight-Weight Power Management and Electronics
Lightweight power transmission
Distributed propulsion control and power systems architectures
Lightweight power electronics
Integrated motor with high power density power electronics
• Multi-KV, Multi-MW power system architecture for aircraft applications
• Power management, distribution and control at MW and subscale (kW) levels
• Integrated thermal management and motor control schemes
• Flightweight conductors, advanced magnetic materials, and insulators
• Collaborations with GE Global Research, Boeing, U of Illinois on flight-weight 1 MW inverters
Lightweight Cryocooler
Superconducting transmission line
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NASA NRAs for 1MW Inverter Development
Key Performance
Metrics
Specific Power (kW/kg)
Specific Power (HP/lb)
Efficiency (%)
Minimum 12 7.3 98.0Goal 19 11.6 99.0
Stretch Target 25 15.2 99.5
Key PerformanceMetrics
Specific Power (kW/kg)
Specific Power (HP/lb)
Efficiency (%)
Minimum 17 10.4 99.1Goal 26 15.8 99.3
Stretch Target 35 21.3 99.4
Cryogenic Temperatures
Ambient Temperatures
• GE – Silicon Carbide TRL 4 in 2018• Univ. of Illinois – Gallium Nitride
• Boeing – Silicon CoolMOS, SiGeTRL 4 in 2019
Key element for generator rectification and motor drive control
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Integrated System Testing and Validation
NASA-GRC PEGSSoftware/Hardware emulationhardware-in-the-loop electrical grid
NASA-AFRC Flight simulator – Flight Dynamics
NASA GRC - NEAT2MW Configurable Power Testbed
NASA-AFRC HEISTIronbird / Hardware in the Loop
• Validate components and power system benefits predictions
• Study component interactions to validate performance and matching at steady-state and transient operation
• Develop MW-level power system testing and modeling capability
• Demonstrate technology at appropriate scale for best research value
• Integrate power, controls, and thermal management into system testing to identify system-level issues early
• Develop and test flight control methodology for distributed propulsion
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• Establish reference hybrid electric propulsion systems for component maturation
• Identify “tall pole” technologies
• Industry collaborations:
− Hybrid-electric geared turbofan concept (UTRC, P&W, UTC Aero Systems)− Hybrid-electric propulsion system concept (Rolls Royce, Boeing, GA Tech)
• Continuously evaluate reference designs
− Inform technology investment strategy− Establish guidelines for technology scalability to commercial transport class
Boeing“SugarVolt”N+3concept NASAN-3Xconcept
Conceptual Designs of Hybrid Electric Propulsion Systems
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Conceptual Designs of Hybrid Electric Propulsion Systems
• Hybrid-electric geared turbofan (hGTF) conceptual design (UTRC, P&W, UTC Aerospace Systems)
• High efficiency drive gear integrating high speed motor and low pressure turbine
• Bi-directional flow of power
• Hybrid battery/fuel cell for energy storage
• Combined fuel/fan thermal management system
• Hybrid gas-electric propulsion system conceptual design (Rolls Royce, Boeing, GA Tech)
• Identify best performing architecture based on engine cycles, motor, power conversion, energy storage, and thermal management
• Innovative integration of novel gas turbine cycles and electrical drives
• Potential side effects of system design considerations
• Provide roadmap and tech maturation plan
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STARC-ABL Turboelectric BLI Aircraft Concept
Welstead et al., Presented at AIAA SciTech, Jan. 2016
Configuration• 154PAXTubeandwing,M=0.7• 2downsized turbines:80%takeoff thrust,
55%cruisethrust• 1electricallypoweraftpropulsor: 20%
takeoffthrust,45%cruisethrust• 2x1.4MWGenerators,2.6MWMotor• ElectricMachinesassumeNASANRA
targetsfor efficiencyandspecificpower
KeyFeatures• Usesexistingairport infrastructure• SOABatteries• Configurationmeetsspeedandrange
requirementofbaselineaircraft• 7-12%fuel(andenergy)consumption
reductioncomparedtobaselineN+3aircraftfor900-3500nmmission
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Concluding Remarks
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The Path Forward…
• Focus on future single-aisle twin engine and large regional jets• Viable concepts with net reduction in energy use• Development of core technologies: turbine-coupled motors, generators,
power system architecture, power electronics, thermal management, flight controls
• Simulation and modeling tools for propulsion, vehicle, electrical, and flight control systems
• Technology demonstrations of components and architectures• Exciting times ahead
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