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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Risk Reduction Testing of Superconducting Coils for the High Efficiency Megawatt Motor

Second generation high temperature superconducting coils provide a very attractive level of performance for use in the field winding of electric machines for aircraft. Aside from maintaining these coils at cryogenic temperatures, much care must be taken to prevent damaging these relatively fragile materials due to excessive stress. Thermal stresses due to temperature cycling and mechanical stresses due to centrifugal forces are the most critical for the High Efficiency Megawatt Motor. This paper summarizes two test campaigns that were undertaken to reduce the risks posed by these loads. In one campaign, several superconducting coils were fabricated, thermally cycled up to 50~times, and electrically tested in liquid nitrogen to assess the change in superconductivity metrics throughout thermal cycling. In the other campaign, a full-scale superconducting coil was fabricated, a test article was designed to produce a representative stress environment in the coil, the test article and coil were rotated at room temperature up to a speed of 11,800~rpm, and the superconductivity metrics were measured in liquid nitrogen before and after each rotation. The experimental results demonstrate that the superconducting coils manufactured in house can survive both thermal cycling and high speed rotation with no appreciable degradation in superconducting performance.

partially superconducting electric machine↗
NASA NTRSDate not supplied

Update on SUSAN Concept Vehicle Power and Propulsion System

This paper provides an update on the power and propulsion (P&P) system design for the SUbsonic Single Aft eNgine (SUSAN) Electrofan. The SUSAN vehicle concept is a transformative concept hybrid electric aircraft with a single tail-mounted turbofan engine that provides thrust and power to 16 electric propulsors located on the wings. This configuration makes uses of large-scale power extraction along with a high-power electrical system transmitting 20 MW of power from the engine to the wing propulsors. This paper goes into detail on P&P advances relating turbine engine design, electrical system capabilities, advanced turbine control techniques, and electrical system cooling techniques. It should be noted that the SUSAN concept continues to be developed and this paper simply offers an update on the design.

aircraft concept↗
NASA NTRSDate not supplied

Update on SUSAN Concept Vehicle Power and Propulsion System

This paper provides an update on the power and propulsion (P&P) system design for the SUbsonic Single Aft eNgine (SUSAN) Electrofan. The SUSAN vehicle concept is a transformative concept hybrid electric aircraft with a single tail-mounted turbofan engine that provides thrust and power to 16 electric propulsors located on the wings. This configuration makes uses of large-scale power extraction along with a high-power electrical system transmitting 20 MW of power from the engine to the wing propulsors. This paper goes into detail on P&P advances relating turbine engine design, electrical system capabilities, advanced turbine control techniques, and electrical system cooling techniques. It should be noted that the SUSAN concept continues to be developed and this paper simply offers an update on the design.

aircraft concept↗
NASA NTRSDate not supplied

Power System Redundancy Design Trends for All-Electric eVTOL Quadrotors

Electrical vertical takeoff and landing (eVTOL) vehicles promise to enable a variety of new local and intraregional air transport missions. However, there are significant challenges that must be solved to enable their use. One challenge is the relatively low reliability of power components (e.g. motors, power electronic devices, and batteries). No clear development path to create reliable eVTOL power systems has been articulated in the literature, though it is generally assumed redundancy is part of the solution. This work proposes an analysis process to examine the redundancy design space and select mass optimal designs for eVTOL power systems. The process is applied to a six passenger quadrotor vehicle, and results are used to highlight redundancy design trends for this class of vehicle. This process and associated data can help vehicle designers more effectively develop eVTOLs that meet reliability requirements.

Electric vertical takeoff and landing↗
NASA NTRSDate not supplied

Power System Redundancy Design Trends for All-Electric eVTOL Quadrotors

Electrical vertical takeoff and landing (eVTOL) vehicles promise to enable a variety of new local and intraregional air transport missions. However, there are significant challenges that must be solved to enable their use. One challenge is the relatively low reliability of power components (e.g. motors, power electronic devices, and batteries). No clear development path to create reliable eVTOL power systems has been articulated in the literature, though it is generally assumed redundancy is part of the solution. This work proposes an analysis process to examine the redundancy design space and select mass optimal designs for eVTOL power systems. The process is applied to a six passenger quadrotor vehicle, and results are used to highlight redundancy design trends for this class of vehicle. This process and associated data can help vehicle designers more effectively develop eVTOLs that meet reliability requirements.

Electric vertical takeoff and landing↗
NASA NTRSDate not supplied

Design and Analysis of Battery Thermal Management Systems

Thermal management of battery cell packs is a critically needed technology. The purpose of this work is to design new and improved Battery Thermal Management Systems (BTMS) for use in electric airplanes. The BTMS should be 3D printable and hold twelve to sixteen 18650 batteries. To minimize aircraft’s weight, an actively air-cooled battery pack was chosen to avoid the excess weight of water-cooled and phase change material (PCM) cooled packs. As a result, significant changes were made to remove all metal in the pack and replace it with lower density polymer matrix composites (PMCs) which can be additively manufactured. Two air cooled battery pack configurations (traditional propeller fans & bladeless fans) were designed, modeled, and compared. These packs were first modeled in SolidWorks 2021 3D CAD, then imported into COMSOL MultiPhysics to be studied using the “Heat Transfer in Solids and Fluids” module. The design with the bladeless fans eliminated the need to use high conductivity heavy metal to remove unwanted thermal energy. These bladeless fans were designed entirely out of PMCs. This thermal pack design weighs 0.04 kg less than that of the traditional propeller fans design and has increased the battery pack energy density by 8.25 Wh/kg.

Thermal Management System for Battery Packs↗
NASA NTRSDate not supplied

Update on SUSAN Concept Vehicle Power and Propulsion System

This paper provides an update on the power and propulsion (P&P) system design for the SUbsonic Single Aft eNgine (SUSAN) Electrofan. The SUSAN vehicle concept is a transformative concept hybrid electric aircraft with a single tail-mounted turbofan engine that provides thrust and power to 16 electric propulsors located on the wings. This configuration makes uses of large-scale power extraction along with a high-power electrical system transmitting 20 MW of power from the engine to the wing propulsors. This paper goes into detail on P&P advances relating turbine engine design, electrical system capabilities, advanced turbine control techniques, and electrical system cooling techniques. It should be noted that the SUSAN concept continues to be developed and this paper simply offers an update on the design.

aircraft concept↗
NASA NTRS2022

Projecting Power Converter Specific Power Through 2050 for Aerospace Applications

In order to analyze the potential fuel burn benefit from the electrification of aircraft powertrains, it is important to quantify the amount of weight that will be added to the aircraft for each additional component of the electric powertrain. This paper provides a projection of the specific power and efficiency of power converters, (AC-DC, DC-AC, or DC-DC), through the year 2050. Data was first collected on state of the art power converters in multiple application areas, creating a power converter database. Relevant specific powers were added to a set of historical data from 1976-2020, and then three different logistic curves were fit through the historical data to represent S-curve shaped growth through the year 2050. The three curves were differentiated by conservative, nominal, and aggressive assumptions for the year in which the logistic curve begins to bend down towards slower growth. With a 30% knockdown factor accounting for the additional weight required for a high altitude converter, projections range from the aggressive specific power projection of 52.9 kW/kg in 2050 to a much more conservative specific power of 12 kW/kg in which growth is limited due to certifiability concerns. Little historical data was found on converter efficiencies to project efficiency based on historical trends. Projections are based on expert opinion on yearly decreases in converter losses. 2050 projections range from 0.987 to 0.997.

fuel burn↗
NASA NTRSDate not supplied

Cryogenic Vacuum Chamber Testing of A Conductively-Cooled, High Temperature Superconducting Rotor for a 1.4 MW Electric Machine for Aeronautics Applications

This paper presents the second ever demonstration of a superconducting rotor cooled only via conductive connection to a cryocooler, i.e., without pumped or solid cryogens. The fullscale rotor was operated statically in its intended environment – about 1e-3 torr vacuum with only conductive cooling through mechanical connections to a cryocooler contained on the rotor. Stable operation of the rotor in a representative magnetic environment was demonstrated up to its rated direct current (57.2 A) and the designed temperature limit for the superconductor (62 K). Additional electrical measurements increased confidence that the superconducting coils functioned as intended. A collection of steady state temperature distributions was measured at operating and non-operating conditions. In all but one case, the observed temperature gradient between the cold tip and superconducting coils satisfies the design but with little margin. Opportunities to reduce the gradient are identified.

Electrified aircraft propulsion↗
NASA NTRSDate not supplied

Cryogenic Vacuum Chamber Testing of A Conductively-Cooled, High Temperature Superconducting Rotor for a 1.4 MW Electric Machine for Aeronautics Applications

This paper presents the first ever demonstration of a superconducting rotor cooled conductively without a cryogenic fluid or solid. The full-scale rotor was operated statically in its intended environment – about 1e-3 torr vacuum with only conductive cooling through mechanical connections to a cryocooler contained on the rotor. Stable operation of the rotor in a representative magnetic environment was demonstrated up to its rated direct current (57.2 A) and the designed temperature limit for the superconductor (62 K). Additional electrical measurements increased confidence that the superconducting coils functioned as intended. A collection of steady state temperature distributions was measured at operating and non-operating conditions. In all but one case, the observed temperature gradient between the cold tip and superconducting coils satisfies the design but with little margin. Opportunities to reduce the gradient are identified.

Electrified aircraft propulsion↗