Feasibility of Electrified Propulsion for Ultra-Efficient Commercial Aircraft Final Report

MIT, Aurora Flight Sciences, and USC have collaborated to assess the feasibility of electric, hybridelectric, and turbo-electric propulsion for ultra-efficient commercial transportation. The work has drawn on the team expertise in disciplines related to aircraft design, propulsion-airframe integration, electric machines and systems, engineering system design, and optimization. A parametric trade space analysis has been carried out to assess vehicle performance across a range of transport missions and propulsion architectures to establish how electrified propulsion systems scale. An optimization approach to vehicle conceptual design modeling was taken to enable rapid multidisciplinary design space exploration and sensitivity analysis. The results of the analysis indicate vehicle aero-propulsive integration benefits enabled by electrification are required to offset the increased weight and loss associated with the electric system and achieve enhanced performance; the report describes the conceptual configurations than can offer such enhancements. The main contribution of the present work is the definition of electric vehicle design attributes for potential efficiency improvements at different scales. Based on these results, key areas for future research are identified, and extensions to the trade space analysis suitable for higher fidelity electrified commercial aircraft design and analysis have been developed

Optimal power system design and energy management for more electric aircrafts

Recent developments in fuel cell (FC) and battery energy storage technologies bring a promising perspective for improving the economy and endurance of electric aircraft. However, aircraft power system configuration and power distribution strategies should be reasonably designed to enable this benefit. This paper is the first attempt to investigate the optimal energy storage system sizing and power distribution strategies for electric aircraft with hybrid FC and battery propulsion systems. First, a novel integrated energy management and parameter sizing (IEMPS) framework is established to co-design aircraft hardware and control algorithms. Under the IEMPS framework, a new real-time power distribution algorithm with a flexible ratio is established to facilitate integrated parameter optimization, which can adapt to different power system configurations. Based on the comprehensive analysis of hydrogen economy, FC aging cost, and aircraft stability, a multi-objective parameter optimization model is established to decide the size of aircraft energy storage systems and hyper-parameters in the power controller. The X-57 Maxwell, an experimental electric aircraft designed by NASA, is employed to verify the developed methods. This work provides a novel power system configuration, sizing, and power management method for future commercial aircraft design, and it can further promote the aviation electrification process.</p

Investigating Optimized Airplane Electrical Power Systems Using Advanced Energy Generation, Storage and Conversion Technologies

This work addresses the optimized integration of new types of electrical power system energy storage and energy generation devices into advanced electrical power systems for commercial airplanes. The objective of this research is to identify how new energy generation and storage system technologies, such as batteries, fuel cells and super capacitors, can be successfully integrated into an optimized and more efficient future airplane electrical power system architectures with success being measured from the standpoint of improvements in airplane, efficiency, reliability and maintainability. The baseline airplane electrical power system architecture that was chosen as a reference starting point for this study is a scaled model of Boeing's 787 "More Electrical Airplane" (MEA) due to its significantly increased electrification in comparison to all other commercial transport airplanes flying today. The 787 power system is unique in that it replaces nearly all of the pneumatically powered systems and some of the hydraulically powered systems with electrical power. This system architecture was incorporated on the 787 in order to provide significant advancements in airplane efficiency and to enable increased airplane performance and range along with decreased fuel burn and an associated decrease in emissions detrimental to the environment.The 787 MEA also incorporates a much more distributed electrical power system architecture and makes significantly increased use of power electronic conversion technology. Similarities can thus be drawn between the MEA and what is occurring with microgrids in the utility industry and electric and fuel cell powered automobiles in the transportation industry. Consequently technical information can be drawn from those industries technologies that potentially is useful in the research and development of an advanced MEA.Through the combination of the simulation and analysis this research shows that incorporation of these new energy generation and storage systems into a future MEA electrical power system along with changes in system conversion systems, electrical loads, and the overall electrical power system architecture would result in a significant increase in overall airplane efficiency along with other improvements for a future MEA

Hybrid Power System Topology and Energy Management Scheme Design for Hydrogen-Powered Aircraft

The electrification of the aviation industry is a major challenge to realizing net-zero in the global energy sector. Fuel cell (FC) hybrid electric aircraft (FCHEV) demonstrate remarkable competitiveness in terms of cruise range and total economy. However, the process of simply hybridizing different power supplies together does not lead to an improvement in the aircraft economy, since a carefully designed power system topology and energy management scheme are also necessary to realize the full benefit of FCHEV. This paper provides a new approach towards the configuration of the optimal power system and proposes a novel energy management scheme for FCHEA. Firstly, four different topologies of aircraft power systems are designed to facilitate flexible power flow control and energy management. Then, an equivalent model of aircraft hydrogen consumption is formulated by analyzing the FC efficiency, FC aging, and BESS aging. Using the newly established model, the performance of aircraft can be quantitatively evaluated in detail to guide FCHEA design. The optimal aircraft energy management is realized by establishing a mathematical optimization model with the reduction of hydrogen consumption and aging costs as objectives. An experimental aircraft, NASA X-57 Maxwell, is used to provide a detailed performance evaluation of different power system topologies and validate the effectiveness of the energy management scheme. The new approach represents a guide for future power system design and energy management of electric aircraft.</p

Sizing Analysis for Aircraft Utilizing Hybrid-Electronic Propulsion Systems

A submerged inlet investigation, using flow control in the form of discrete blowing, examined proximity and jet directionality to improve compressor face uniformity. The flow control locations were at the head of the ramp and part way down the ramp, providing four configurations under examination. Laser Doppler velocimetry (LDV)measurements at the throat determined the effect of the flow control based on the statistical velocity measurements. Blowing at closer proximity to the throat and targeting the largest velocity deficit region provided the best results. The airspeed and inlet velocity simulated takeoff and landing conditions; velocities ranged from Mach 0.1-0.3 at the throat. Secondary components and turbulence measurements proved useful in determining the effect of the flow control configurations. In a complimentary study, two serpentine ducts of rectangular cross-section evaluated the LDV capability before the inlet examination. The s-shaped serpentine ducts had features comparable to those expected in the submerged inlet. The flow through two serpentine ducts, of identical hydraulic diameters but different aspect ratios, demonstrated different behaviors despite all other features being the same. Two strong counter-rotating streamwise vortices formed for the 2:1 aspect ratio while four weaker vortices formed in the 1:2 aspect ratio duct. Computational simulations, performed on the serpentine ducts using a Reynolds shear stress model on a 4 million cell grid, agreed with the results of the experimental examination. The agreement between the exit profiles provided confidence in the LDV system to make the inlet measurements possible

Conceptual design of battery energy storage for aircraft hybrid propulsion system

The paper presents a conceptual design approach for Energy Storage (ES) devices in advanced hybrid propulsion system for small aircrafts. The study targets operational improvement and reduction of fuel consumption for different flight missions. Power sharing strategies for ES and the engine are proposed for cruise flight phase aiming to maximise the range and/or endurance for the available amount of fuel in the tank. The ES size is designed against the engine performance and the proposed power sharing strategy by optimizing the flight altitude

12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"

Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin

Stability, Transient Response, Control, and Safety of a High-Power Electric Grid for Turboelectric Propulsion of Aircraft

This document contains the deliverables for the NASA Research and Technology for Aerospace Propulsion Systems (RTAPS) regarding the stability, transient response, control, and safety study for a high power cryogenic turboelectric distributed propulsion (TeDP) system. The objective of this research effort is to enumerate, characterize, and evaluate the critical issues facing the development of the N3-X concept aircraft. This includes the proposal of electrical grid architecture concepts and an evaluation of any needs for energy storage

DESIGN OF A PROTOTYPE UNMANNED LIGHTER-THAN-AIR PLATFORM FOR REMOTE SENSING: CONTROL, ALIMENTATION, AND PROPULSION SYSTEMS

This work presents several aspects related to the design of a new concept for a Remotely Piloted Aircraft System (RPAS), specifically, a Lighter-Than-Air (LTA) platform for the remote sensing of medium-sized rural and urban areas. The airship’s payload is intended to carry an array of sensors ranging from high-definition video cameras to hyperspectral sensors, a thermographic camera, and a LiDAR system, which all require power alimentation during low-speed surveying for fine mapping. Here, a fuel cell design solution, combined with supercapacitors, is proposed. The system is designed to provide energy for both the onboard sensors and the propulsion and thrust vector control system. In this regard, the design and optimization of the propeller blades, using Blade Element Momentum Theory (BEMT), is discussed as well, in a multidisciplinary optimisation fashion. A twin paper describes the other structural aspects of the airship design