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  • Other Sources  (8)
  • Aircraft Propulsion and Power  (7)
  • Spacecraft Propulsion and Power  (1)
  • 1
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    Liquid-Hydrogen-Cooled 450-hp Electric Motor Test Stand Being Developed (2005)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: With growing concerns about global warming, there is a need to develop pollution-free aircraft. One approach is to use hydrogen-fueled aircraft that use fuel cells or turbogenerators to produce electric power to drive the electric motors that turn the aircraft s propulsive fans. Hydrogen fuel would be carried as a liquid, stored at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are too heavy for aircraft propulsion. We need to develop high-power, lightweight electric motors (highpower- density motors). One approach is to increase the conductivity of the wires by cooling them with liquid hydrogen (LH2). This would allow superconducting rotors with an ironless core. In addition, the motor could use very pure aluminum or copper, substances that have low resistances at cryogenic temperatures. A preliminary design of a 450-hp LH2-cooled electric motor was completed and is being manufactured by a contractor. This motor will be tested at the NASA Glenn Research Center and will be used to test different superconducting materials such as magnesium diboride (MgB2). The motor will be able to operate at speeds of up to 6000 rpm.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2004; NASA/TM-2005-213419
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Liquid-Hydrogen-Cooled 450-hp Electric Motor Test Stand Being Developed (2005)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: With growing concerns about global warming, there is a need to develop pollution-free aircraft. One approach is to use hydrogen-fueled airc raft that use fuel cells or turbogenerators to produce electric power to drive the electric motors that turn the aircraft#s propulsive fan s. Hydrogen fuel would be carried as a liquid, stored at its boiling point of 20.5 K (-422.5 ?F). Conventional electric motors, however, are too heavy to use on an aircraft. We need to develop high-power, lig htweight electric motors (high-powerdensity motors).
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2004; NASA/TM-2005-213419
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    NASA TECHNICAL REPORTS
  • 3
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    "Fan-Tip-Drive" High-Power-Density, Permanent Magnet Electric Motor and Test Rig Designed for a Nonpolluting Aircraft Propulsion Program (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A scaled blade-tip-drive test rig was designed at the NASA Glenn Research Center. The rig is a scaled version of a direct-current brushless motor that would be located in the shroud of a thrust fan. This geometry is very attractive since the allowable speed of the armature is approximately the speed of the blade tips (Mach 1 or 1100 ft/s). The magnetic pressure generated in the motor acts over a large area and, thus, produces a large force or torque. This large force multiplied by the large velocity results in a high-power-density motor.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    High-Temperature Magnetic Bearings Being Developed for Gas Turbine Engines (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and cooperation with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of bearing times the rpm) limit on engine speed and allow active vibration cancellation systems to be used, resulting in a more efficient, "more electric" engine. Finally, the Integrated High Performance Turbine Engine Technology (IHPTET) program, a joint Department of Defense/industry program, identified a need for a high-temperature (1200 F) magnetic bearing that could be demonstrated in their Phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator's circumference are a series of electrical wire coils which form a series of electric magnets that exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it centered in the cavity. The engine rotor, bearings, and casing form a flexible structure with many modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 1997; NASA/TM-1998-206312
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    In Operation Detection and Correction of Rotor Imbalance in Jet Engines Using Active Vibration Control (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Jet Engines may experience severe vibration due to the sudden imbalance caused by blade failure. This research investigates employment of on board magnetic bearings or piezoelectric actuators to cancel these forces in flight. This operation requires identification of the source of the vibrations via an expert system, determination of the required phase angles and amplitudes for the correction forces, and application of the desired control signals to the magnetic bearings or piezo electric actuators. This paper will show the architecture of the software system, details of the control algorithm used for the sudden imbalance correction project described above, and the laboratory test results.
    Keywords: Aircraft Propulsion and Power
    Type: SAE-TP-941151 , (ISSN 0148-7191)|Aerospace Atlantic Conference and Exposition; Apr 18, 1994 - Apr 22, 1994; Dayton, OH; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Propulsion Investigation for Zero and Near-Zero Emissions Aircraft (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: As world emissions are further scrutinized to identify areas for improvement, aviation s contribution to the problem can no longer be ignored. Previous studies for zero or near-zero emissions aircraft suggest aircraft and propulsion system sizes that would perform propulsion system and subsystems layout and propellant tankage analyses to verify the weight-scaling relationships. These efforts could be used to identify and guide subsequent work on systems and subsystems to achieve viable aircraft system emissions goals. Previous work quickly focused these efforts on propulsion systems for 70- and 100-passenger aircraft. Propulsion systems modeled included hydrogen-fueled gas turbines and fuel cells; some preliminary estimates combined these two systems. Hydrogen gas-turbine engines, with advanced combustor technology, could realize significant reductions in nitrogen emissions. Hydrogen fuel cell propulsion systems were further laid out, and more detailed analysis identified systems needed and weight goals for a viable overall system weight. Results show significant, necessary reductions in overall weight, predominantly on the fuel cell stack, and power management and distribution subsystems to achieve reasonable overall aircraft sizes and weights. Preliminary conceptual analyses for a combination of gas-turbine and fuel cell systems were also performed, and further studies were recommended. Using gas-turbine engines combined with fuel cell systems can reduce the fuel cell propulsion system weight, but at higher fuel usage than using the fuel cell only.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2009-215487 , E-16693
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    NASA Glenn Research Center Program in High Power Density Motors for Aeropropulsion (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: Electric drive of transport-sized aircraft propulsors, with electric power generated by fuel cells or turbo-generators, will require electric motors with much higher power density than conventional room-temperature machines. Cryogenic cooling of the motor windings by the liquid hydrogen fuel offers a possible solution, enabling motors with higher power density than turbine engines. Some context on weights of various systems, which is required to assess the problem, is presented. This context includes a survey of turbine engine weights over a considerable size range, a correlation of gear box weights and some examples of conventional and advanced electric motor weights. The NASA Glenn Research Center program for high power density motors is outlined and some technical results to date are presented. These results include current densities of 5,000 A per square centimeter current density achieved in cryogenic coils, finite element predictions compared to measurements of torque production in a switched reluctance motor, and initial tests of a cryogenic switched reluctance motor.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2005-213800 , ARL-MR-0628 , E-15158
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Bleed Cycle Propellant Pumping in a Gas-Core Nuclear Rocket Engine System (1972)
    In:  CASI
    Details
    Publication Date: 2019-09-18
    Description: The performance of ideal and real staged primary propellant pumps and bleed-powered turbines was calculated for gas-core nuclear rocket engines over a range of operating pressures from 500 to 5000 atm. This study showed that for a required engine operating pressure of 1000 atm the pump work was about 0.8 hp/(lb/sec), the specific impulse penalty resulting from the turbine propellant bleed flow as about 10 percent; and the heat required to preheat the propellant was about 7.8 MW/(lb/sec). For a specific impulse above 2400 sec, there is an excess of energy available in the moderator due to the gamma and neutron heating that occurs there. Possible alternative pumping cycles are the Rankine or Brayton cycles.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA-TM-X-2517 , E-6639
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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