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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

High-Temperature Hybrid Rotor Support System Developed

The Army Research Laboratory Vehicle Technology Directorate and the NASA Glenn Research Center demonstrated a unique high-speed, high-temperature rotor support system in September 2003. Advanced turbomachinery is on its way to surpassing the capabilities of rolling-element bearings and conventional dampers. To meet these demands, gas turbine engines of the future will demand increased efficiency and thrust-to-weight ratio, and reduced specific fuel consumption and noise. The more-electric engine replaces oil-lubricated bearings, dampers, gears, and seals with electrical devices. One such device is the magnetic bearing. The Vehicle Technology Directorate and Glenn have demonstrated the operation of a radial magnetic bearing in combination with a hydrostatic bearing at 1000 F at 31,000 rpm (2.3 MDN1). This unique combination takes advantage of a high-temperature rub surface in the event of electrical power loss or sudden overloads. The hydrostatic bearings allow load sharing with the magnetic bearing. The magnetic-hydrostatic bearing combination eliminates wear and high contact stress from sudden acceleration of the rolling-element bearings and overheating. The magnetic bearing enables high damping, adaptive vibration control, and precise rotor positioning, diagnostics, and health monitoring. A model of the test facility used at Glenn for this technology demonstration is shown. A high-temperature heteropolar radial magnetic bearing is located at the center of gravity of the test rotor. There is a 0.022-in. radial air gap between the rotor and stator. Two rub surface hydrostatic bearings were placed on either side of the magnetic bearing. The rotor is supported by a 0.002-in. hydrostatic air film and the magnetic field. The prototype active magnetic bearing cost $24,000 to design and fabricate and a set of four high temperature, rub-surface, hydrostatic bearings cost $28,000. This work was funded by the Turbine-Based Combined Cycle program.

Montague, Gerald T.↗
NASA NTRS2007

A New High-Speed Oil-Free Turbine Engine Rotordynamic Simulator Test Rig

A new test rig has been developed for simulating high-speed turbomachinery rotor systems using Oil-Free foil air bearing technology. Foil air bearings have been used in turbomachinery, primarily air cycle machines, for the past four decades to eliminate the need for oil lubrication. The goal of applying this bearing technology to other classes of turbomachinery has prompted the fabrication of this test rig. The facility gives bearing designers the capability to test potential bearing designs with shafts that simulate the rotating components of a target machine without the high cost of building "make-and-break" hardware. The data collected from this rig can be used to make design changes to the shaft and bearings in subsequent design iterations. This paper describes the new test rig and demonstrates its capabilities through the initial run with a simulated shaft system.

Howard, Samuel A.↗
NASA NTRS2009

Gadolinia-Doped Ceria Cathodes for Electrolysis of CO2

Gadolinia-doped ceria, or GDC, (Gd(0.4)Ce(0.6)O(2-delta), where the value of delta in this material varies, depending on the temperature and oxygen concentration in the atmosphere in which it is being used) has shown promise as a cathode material for high-temperature electrolysis of carbon dioxide in solid oxide electrolysis cells. The polarization resistance of a GDC electrode is significantly less than that of an otherwise equivalent electrode made of any of several other materials that are now in use or under consideration for use as cathodes for reduction of carbon dioxide. In addition, GDC shows no sign of deterioration under typical temperature and gas-mixture operating conditions of a high-temperature electrolyzer. Electrolysis of CO2 is of interest to NASA as a way of generating O2 from the CO2 in the Martian atmosphere. On Earth, a combination of electrolysis of CO2 and electrolysis of H2O might prove useful as a means of generating synthesis gas (syngas) from the exhaust gas of a coal- or natural-gas-fired power plant, thereby reducing the emission of CO2 into the atmosphere. The syngas a mixture of CO and H2 could be used as a raw material in the manufacture, via the Fisher-Tropsch process, of synthetic fuels, lubrication oils, and other hydrocarbon prod

Adler, Stuart B.↗
NASA NTRS2001

A Cooling System for the EAPU Shuttle Upgrade

The Shuttle orbiter currently uses hydrazine-powered APU's for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges most notably the new requirement for moderate temperature control of high-power electron ics at 132 of (55.6 C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.

Tongue, Stephen↗
NASA NTRS2012

Rudimentary Cleaning Compared to Level 300A

A study was done to characterize the cleanliness level achievable when using a rudimentary cleaning process, and results were compared to JPR 5322.1G Level 300A. While it is not ideal to clean in a shop environment, some situations (e.g., field combat operations) require oxygen system hardware to be maintained and cleaned to prevent a fire hazard, even though it cannot be sent back to a precision cleaning facility. This study measured the effectiveness of basic shop cleaning. Initially, three items representing parts of an oxygen system were contaminated: a metal plate, valve body, and metal oxygen bottle. The contaminants chosen were those most likely to be introduced to the system during normal use: oil, lubricant, metal shavings/powder, sand, fingerprints, tape, lip balm, and hand lotion. The cleaning process used hot water, soap, various brushes, gaseous nitrogen, water nozzle, plastic trays, scouring pads, and a controlled shop environment. Test subjects were classified into three groups: technical professionals having an appreciation for oxygen hazards; professional precision cleaners; and a group with no previous professional knowledge of oxygen or precision cleaning. Three test subjects were in each group, and each was provided with standard cleaning equipment, a cleaning procedure, and one of each of the three test items to clean. The results indicated that the achievable cleanliness level was independent of the technical knowledge or proficiency of the personnel cleaning the items. Results also showed that achieving a Level 300 particle count was more difficult than achieving a Level A nonvolatile residue amount.

Arpin, Christina Y. Pina↗
NASA NTRS2012

Terrestrial Applications of Extreme Environment Stirling Space Power Systems

NASA has been developing power systems capable of long-term operation in extreme environments such as the surface of Venus. This technology can use any external heat source to efficiently provide electrical power and cooling; and it is designed to be extremely efficient and reliable for extended space missions. Terrestrial applications include: use in electric hybrid vehicles; distributed home co-generation/cooling; and quiet recreational vehicle power generation. This technology can reduce environmental emissions, petroleum consumption, and noise while eliminating maintenance and environmental damage from automotive fluids such as oil lubricants and air conditioning coolant. This report will provide an overview of this new technology and its applications.

Dyson, Rodger. W.↗
NASA NTRS2012

Thermophysical Properties of 60-NITINOL for Mechanical Component Applications

The linear thermal expansion coefficient, specific heat capacity, electrical resistivity and thermal conductivity of 60- NITINOL were studied over a range of temperatures representing the operating environment of an oil-lubricated bearing. The behavior of this material appears to follow wellestablished theories applicable to either metal alloys, in general, or to intermetallic compounds, more specifically and the measured data were found to be comparable to those for conventional bearing alloys.

Stanford, Malcolm K.↗
NASA NTRSDate not supplied

Design Study of a Coupled Inner-Stator Magnetically Geared Motor for Electric Aircraft Applications

Electric aircraft require high performance and high reliability electric motor drivetrains. A geared electric motor drivetrain will outperform a direct drive motor drivetrain in most applications. Traditional mechanical gearing, however, has mechanical contact-based wear and failure modes that result in added maintenance costs and require an oil lubrication system. Magnetically geared motor drives are a potential technology for electric aircraft applications capable of enabling the benefits of a geared drive without the maintenance, reliability, and lubrication system cost of mechanical gears. In this paper, a topology of magnetically geared motor, an inner stator magnetically geared motor, is explored to estimate its achievable performance for electric aircraft applications. Optimization results on the topology show that it can achieve greater than 15 Nm/kg and 96% efficiency at 100 kW of power.

Thomas Tallerico↗
NASA NTRSDate not supplied

Design Study of a Coupled Inner-Stator Magnetically Geared Motor for Electric Aircraft Applications

Abstract- Electric aircraft require high performance and high reliability electric motor drivetrains. A geared electric motor drivetrain will outperform a direct drive motor drivetrain in most applications. Traditional mechanical gearing, however, has mechanical contact-based wear and failure modes that result in added maintenance costs and require an oil lubrication system. Magnetically geared motor drives are a potential technology for electric aircraft applications capable of enabling the benefits of a geared drive without the maintenance, reliability, and lubrication system cost of mechanical gears. In this paper, a topology of magnetically geared motor, an inner-stator magnetically geared motor, is explored to estimate its achievable performance for electric aircraft applications. Optimization results on the topology show that it can achieve greater than 15 Nm/kg specific torque and 96% efficiency at 100 kW of power.

Thomas Tallerico↗
DOE OSTI2022

Ultra efficient turbo-compression cooling systems

Aspects of the present disclosure include a system for turbo-compression cooling. The system may be aboard a marine vessel. The system includes a power cycle and a cooling cycle. The power cycle includes a first working fluid, a waste heat boiler configured to evaporate the working fluid, a turbine, and a condenser. The condenser condenses the working fluid to a saturated or subcooled liquid. The cooling cycle includes a second working fluid, a first compressor configured to increase the pressure of the second working fluid, a condenser configured to condense the second working fluid to a saturated or subcooled liquid after exiting the first compressor, an expansion valve, and an evaporator. The turbine and first compressor are coupled one to the other. The waste heat boiler receives waste heat from engine jacket water and lubricating oil from a ship service generator. The evaporator cools water in a shipboard cooling loop.

Bandhauer, Todd M.↗
DOE OSTI2025

ENVIRONMENTAL DEGRADATION OF HARD AND SOFT MAGNETIC MATERIALS IN GASEOUS AND SUPERCRITICAL CO2 ENVIRONMENTS

It may be beneficial to use hermetic designs for supercritical CO2 (sCO2) cycles machinery as they would eliminate CO2 leakage through shaft end seals. This would reduce CO2 emissions and operating costs for makeup of lost process fluid. Those designs may replace traditional oil-lubricated bearings with actively controlled magnetic bearings operating at high temperatures in the process fluid environment (to reduce the need for active cooling). This paper investigates the material degradation of various types of magnets in CO2. Included are several permanent and soft magnetic materials (Alnico 9C, Alnico 5-7C, and 18-T550 grade SmCo, and Hiperco 50) with or without coatings (nickel plating or C5 coating). The materials were exposed to: (1) flowing gaseous CO2 at 1,022 °F (550 °C) and atmospheric pressure in a furnace and (2) sCO2 at 842 °F (450 °C) and 1,500 psi (103 bar) in an autoclave. The preliminary mass change measured after total exposures of 1,000 hours and 2,000 hours are included.

supercritical CO2, magnetic material↗
NASA NTRS1982

Into Mesh Lubrication of Spur Gears with Arbitrary Offset Oil Jet. 2: for Jet Velocities Equal to or Greater than Great Velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or greater than gear pitch line velocity. Equations were developed for minimum and maximum oil jet impingement depth. The analysis also included the minimum oil jet velocity required to impinge on the gear or pinion and the optimum oil jet velocity required to obtain the best lubrication condition of maximum impingement depth and gear cooling. It was shown that the optimum oil jet velocity for best lubrication and cooling is when the oil jet velocity equals the gear pitch line velocity. When the oil jet velocity is slightly greater than the pitch line velocity the loaded side of the driven gear and the unloaded side of the pinion receive the best lubrication and cooling with slightly less impingement depth. As the jet velocity becomes much greater than the pitch line velocity the impingement depth is considerably reduced and may completely miss the pinion.

Akin, L. S.↗
NASA NTRS1976

Oil-air mist lubrication as an emergency system and as a primary lubrication system

The feasibility of an emergency aspirator once-through lubrication system was demonstrated as a viable survivability concept for Army helicopter mainshaft engine bearings for periods as long as 30 minutes. It was also shown in an experimental study using a 46-mm bore bearing test machine that an oil-air mist once-through system with auxiliary air cooling is an effective primary lubrication system at speeds up to 2,500,000 DN for extended operating periods of at least 50 hours.

Loomis, W. R.↗
NASA NTRS1982

Into Mesh Lubrication of Spur Gears with Arbitrary Offset Oil Jet. I: For Jet Velocity Less than or Equal to Gear Velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.

Akin, L. S.↗
NASA NTRS1983

Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.

Akin, L. S.↗