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  • MACHINERY  (2)
  • Spacecraft Propulsion and Power  (1)
  • 1
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    Dual-Actuator Active Vibration-Control System (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Dual-actuator active vibration-control (DAAVC) system is developmental system of type described in "Active Vibration Dampers for Rotating Machinery" (LEW-15427). System features sensors and actuators positioned and oriented at bearings to measure and counteract vibrations of shaft along either of two axes perpendicular to axis of rotation. Effective in damping vibrations of helicopter-engine test stand, making it safer to operate engine at speeds near and above first resonance of engine/test-stand system. Opens new opportunities for engine designers to draw more power from engine, and concept applicable to other rotating machines.
    Keywords: MACHINERY
    Type: LEW-15765 , NASA Tech Briefs (ISSN 0145-319X); 18; 12; P. 74
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Piezoelectric Pushers Suppress Vibrations (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Vibration-suppressing control systems including piezoelectric actuators undergoing development. Small, lightweight, and rugged. Requires simpler electronic control subsystems and does not require large electromagnet coils. Continues to provide support and some passive damping even when electronic control subsystems or power supplies fail. Intended primarily to enhance safety and prevent damage in rotating machinery by sensing and counteracting vibrations. Useful in suppressing unpredictable vibrations caused by changes in loads, losses of rotating components and consequent imbalances in rotors, and ingestion of foreign objects into turbines.
    Keywords: MACHINERY
    Type: LEW-14927 , NASA Tech Briefs (ISSN 0145-319X); 14; 8; P. 59
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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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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