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  • 1
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    Control of rotordynamic instability in a typical gas turbine's power system (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effect of rotor internal friction on the system's stability was studied when operated above the first critical speed. This internal friction is commonly caused by sliding press fits or sliding splines. Under conditions of high speed and low bearing damping, these systems will occassionally whirl at a frequency less than the shaft's rotational speed. This subsynchronous precession is a self excited phenomenon and stress reversals are created. This phenomenon was observed during engine testing. The reduction of spline friction and/or the inclusion of squeeze film damping have controlled the instability. Case history and the detail design of the squeeze film dampers is discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA. Lewis Research Center Rotordynamic Instability Problems in High-Performance Turbomachinery; p 53-80
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Trajectory characteristics for a cometary mission. (1965)
    In:  Other Sources
    Details
    Publication Date: 2019-05-30
    Description: Spacecraft-comet rendezvous trajectory analyzed in terms of comet properties and spacecraft capabilities to determine feasibility of interception mission
    Keywords: SPACE SCIENCES
    Type: AIAA PAPER 63-413
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    A design study of hydrazine and biowaste resistojets (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A generalized modeling program was adapted in BASIC on a personal computer to compare the performance of four types of biowaste resistojets and two types of hydrazine augmenters. Analyzed biowaste design types were: (1) an electrically conductive ceramic heater-exchanger of zirconia; (2) a truss heater of platinum in cross flow; (3) an immersed bicoiled tubular heater-exchanger; and (4) a nonexposed, refractory metal, radiant heater in a central cavity within a heat exchanger case. Concepts 2 and 3 are designed to have an efficient, stainless steel outer pressure case. The hydrazine design types are: (5) an immersed bicoil heater exchanger and (6) a nonexposed radiant heater now with a refractory metal case. The ceramic biowaste resistojet has the highest specific impulse growth potential at 2000 K of 192.5 (CO2) and 269 s (H2O). The bicoil produces the highest augmenter temperature of 1994 K for a 2073 K heater giving 317 s at .73 overall efficiency. Detailed temperature profiles of each of the designs are shown. The scaled layout drawings of each are presented with recommended materials and fabrication methods.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-179510 , NAS 1.26:179510
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Slip casting and extruding shapes of rhenium with metal oxide additives. 1: Feasibility demonstration (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of fabricating small rhenium parts with metal oxide additives by means of slip casting and extrusion techniques is described. The metal oxides, ZrO2 and HfO2 were stabilized into the cubic phase with Y2O3. Additions of metal oxide to the rhenium of up to 15 weight percent were used. Tubes of 17 mm diameter with 0.5 mm walls were slip cast by adapting current ceramic oxide techniques. A complete cast double conical nozzle demonstrated the ability to meet shapes and tolerances. Extrusion of meter long tubing lengths of 3.9 mm o.d. x 2.3 mm i.d. final dimension is documented. Sintering schedules are presented to produce better than 95% of theoretical density parts. Finished machining was found possible were requried by electric discharge machining and diamond grinding.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-174970 , NAS 1.26:174970
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    3 kw concentric tubular resistojet performance compared with theory. (1966)
    In:  Other Sources
    Details
    Publication Date: 2019-05-30
    Description: Resistojet design and fabrication, using hydrogen propellant and having 3-kw power input
    Keywords: PROPULSION SYSTEMS
    Type: AIAA PAPER 66-224
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    The design and performance of a 3kw concentric tube resistojet final report (1965)
    In:  CASI
    Details
    Publication Date: 2019-05-24
    Description: Hydrogen propelled 3kW concentric tube resistojet engine design and performance
    Keywords: PROPULSION SYSTEMS
    Type: NASA-CR-54410 , TMC-25168
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    CURRENT STATUS AND PROSPECTS OF ELECTROTHERMAL PROPULSION (1962)
    In:  Other Sources
    Details
    Publication Date: 2019-05-11
    Description: Survey of the status of electrothermal propulsion from engine development viewpoint and discussion of arc jet and resistojet engines
    Keywords: PROPELLANTS
    Type: ARS PAPER 62-2649
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Incipient separation pressure rise for a Mach 3.8 turbulent boundary layer. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Additional incipient separation data presented cover a range of Reynolds numbers not covered in previous investigations conducted by Seebaugh (1968) and Rose (1972). A novel technique for detecting incipient separation is discussed. Several methods for detecting separation are considered. One method is based on the introduction of alcohol at a minute rate into the boundary layer.
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 11; May 1973
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Evaluation of advanced component concepts for an integrated environmental control/life support, resistojet control system (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Flow restricting devices were studied for their suitability as liquid water propellant flow limiters for the biowaste resistojet. Flow limiting during the start-up transient is required to prevent thrustor instabilities and icing which could result in heater failure in the electrical resistance heated thrustor (resistojet). The study was directed toward simple devices which would function passively (i.e., without power except from the propellant flow itself), and would offer high reliability and simplicity. In addition to the flow limiting devices, a thermal pumping system was studied to determine whether CO2, desorbed from molecular sieves could be pumped thermally in a space station application. The thermal pump is considered a possible replacement for mechanical pumps. It involves a cyclic, constant volume cryopumping system which employs space radiators to achieve the cryotemperatures. The frozen CO2 would be vaporized periodically, using a waste heat loop, to attain sufficient pressure to transfer a large portion of the trapped CO2 to storage tanks.
    Keywords: BIOTECHNOLOGY
    Type: NASA-CR-112104
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Evaluation of zirconia, thoria and zirconium diboride for advanced resistojet use (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A literature survey was conducted to collect material properties data on all advanced high temperature materials. Three of these, Y2O3-stabilized ZrO2, ThO2, and ZrB2 with additives of C and SiC were selected for further study. Stabilized ZrO2 and ThO2 were found to have higher temperature oxidation resistance than any metal and great potential for use in advanced biowaste resistojets. ZrO2 has a lower electrical resistivity and sublimation and a higher creep endurance strength. ZrO2 and ThO2 tubular heat exchangers, electrically heated indirectly, were evaluated in short tests to about 1900 K in flowing CO2. ZrO2 was subjected to N2, H2, H2O and vacuum as well. X-ray diffraction and fluorescence analyses were made. The metal-to-ceramic seal technology for ZrO2 and ThO2 was developed using chemical vapor deposition of tantalum for metallizing and 82 Au - 18 Ni filler braze.
    Keywords: MATERIALS, NONMETALLIC
    Type: NASA-CR-112075
    Format: application/pdf
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