Document
Overview of NASA GRC
Elecrified Aircraft Propulsion
Systems Analysis Methods
Sydney Schnulo NASA Glenn Research Center Propulsion Systems Analysis Branch EnergyTech 2017 Cleveland, OH October 31, 2017
Electrified aircraft propulsion requires a
higher level of system level coupling than
analyses of traditional subsonic gas turbine
engine aircraft concepts.
Mission Analysis Environmental NOx Analysis fuel burn Coarse Vehicle & Vehicle Mission & Aircraft Model Mission Definition Acoustic Analyses n oise Thermodynamic Analysis Coarse Propulsion Cycle Model & Cycle Performance Aircraft/Market Propulsion/ System Component Studies & Flight Economic Airframe cost Requirements & Performance Envelope Evaluation Integration Assessment Technology Level Definition Requirements Preliminary Preliminary Engine Economic Conceptual Flowpath & Weight cost Assessment Component Design Assessment Economic Analysis Preliminary Conceptual Design *From 1998 PSAO Benchmark Peer Review
Traditionally, system level studies of advanced aircraft
concepts are split into airframe and propulsion analyses
Typical Outputs:
Aircraft Design
• Engine size/weights • Aircraft Thrust Requirements size/weights • V ehicle Net Thrust , Fuel Flow Propulsion System Weight range • Fuel burn • Emissions • N oise
Propulsion System Design
Traditionally, system level studies of advanced aircraft
concepts are split into airframe and propulsion analyses
Vehicle Sizing &
Vehicle
Typical Outputs:
Mission Analysis
Aerodynamics Weights
• Engine size/weights • Aircraft Thrust Requirements size/weights • V ehicle Net Thrust , Fuel Flow Propulsion System Weight range • Fuel burn
Engine and
• Emissions
Engine Engine Flowpath
• N oise
Airframe
Thermodynamics & Weights
Acoustics
Traditionally, system level studies of advanced aircraft
concepts are split into airframe and propulsion analyses
Vehicle Sizing &
Vehicle
Typical Outputs:
Mission Analysis
Aerodynamics Weights
• Engine size/weights • Aircraft Thrust Requirements size/weights • V ehicle Net Thrust , Fuel Flow Propulsion System Weight range • Fuel burn
Engine and
• Emissions
Engine Engine Flowpath
• N oise
Airframe
Thermodynamics & Weights
Acoustics
On - Design and Off - Design Phases of Cycle
Analysis
Thermodynamic Cycle Analysis
Turbomachinery Performance Maps and
Scaling Equations for Cycle Analysis
The data is passed from propulsion cycle
analysis to mission analysis in the form of an
engine deck
Mission analysis yields the block fuel burn.
Hybrid - electric and Turbo - electric concepts are
highly coupled
Thermal Management Propulsion System System Airframe Power System
Turbo - electric systems modeling: STARC - ABL
• S ingle aisle T urboelectric A i RC raft with A ft B oundary L ayer ingestion • Conventional tube and wing airframe • Two underwing turbofans electrically power a tailcone propulsor while also generating thrust • Welstead , J. and Felder, J., “Conceptual Design of a Single - Aisle Turboelectric Commercial Transport with Fuselage Boundary Layer Ingestion”, 2016
Turbo - electric systems modeling: STARC - ABL
Generator Turbofan Tailcone Motor Propulsor The system level models of the electric power system Generator Turbofan require outputs of component specific power, efficiency, and rpm.
Turbo - electric systems modeling: STARC - ABL
Further analyses
continue to refine the
STARC - ABL concept by
optimizing the coupling
of the systems.
[Gray 2017]
Fully electric system modeling: X - 57 Maxwell
• S calable C onvergent E lectric P ropulsion T echnology and O perations R esearch (SCEPTOR) • Fully electric experimental aircraft to demonstrate a 5 times reduction in energy use at cruise using distributed electric Borer, N. K., Patterson, M. D., Viken , J. K., Moore, M. D., propulsion Bevirt , J., Stoll, A. M., and Gibson, A. R., “Design and Performance of the NASA SCEPTOR Distributed Electric Propulsion Flight Demonstrator," Jun 2016.
Electric System Model
Electric System Model: Battery Modeling
Electric System Model
̇ ̇ ̇ 𝑄 = 𝑄 − 𝑄 %&'&()*&+ -../ ̇ 𝑄 ̇ 𝑇 = 𝐻𝐶
Results of Coupled Analysis
• Successfully determined an optimal trajectory subject to thermal constraints of electric components.
• Modeled the interaction of the propulsion system, airframe, thermal management, and power system.
• Falck , R., Chin, J., Schnulo, S., Burt, J., and Gray, J., “Trajectory Optimization of Electric Aircraft Subject to Subsystem Thermal Constraints," 2016 .
Conclusions
• The accurate modeling and analysis of electrified aircraft propulsion
concepts require intricate subsystem component coupling.
• The major challenge in electrified aircraft propulsion concept
modeling lies in understanding how the subsystems “talk” to each
other and the dependencies they have on one another.
Thank you.