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  • Other Sources  (17)
  • FLUID MECHANICS AND HEAT TRANSFER  (10)
  • ENGINEERING (GENERAL)  (7)
  • 1
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    Calorimetric thermal-vacuum performance characterization of the BAe 80 K space cryocooler (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A comprehensive characterization program is underway at JPL to generate test data on long-life, miniature Stirling-cycle cryocoolers for space application. The key focus of this paper is on the thermal performance of the British Aerospace (BAe) 80 K split-Stirling-cycle cryocooler as measured in a unique calorimetric thermal-vacuum test chamber that accurately simulates the heat-transfer interfaces of space. Two separate cooling fluid loops provide precise individual control of the compressor and displacer heatsink temperatures. In addition, heatflow transducers enable calorimetric measurements of the heat rejected separately by the compressor and displacer. Cooler thermal performance has been mapped for coldtip temperatures ranging from below 45 K to above 150 K, for heatsink temperatures ranging from 280 K to 320 K, and for a wide variety of operational variables including compressor-displacer phase, compressor-displacer stroke, drive frequency, and piston-displacer dc offset.
    Keywords: ENGINEERING (GENERAL)
    Type: In: IECEC '92; Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, San Diego, CA, Aug. 3-7, 1992. Vol. 5 (A93-25851 09-44); p. 5.101-5.107.
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  • 2
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    Vibration characterization and control of miniature Stirling-cycle cryocoolers for space application (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: This paper provides a summary overview of the vibration characteristics of split Stirling cryocoolers of the Oxford type and describes means being developed to achieve vibration levels consistent with the exacting requirements of sensitive infrared spectrometer instruments currently under development for NASA applications. A key emphasis of the paper is on exploring both active and passive means of reducing the residual upper harmonics of the drive frequency that remain with nulled back-to-back compressor and displacer units. Vibration supression results, measured with JPL's unique six-DOF force dynamometer, are presented for an 80 K Stirling cooler.
    Keywords: ENGINEERING (GENERAL)
    Type: In: Advances in cryogenic engineering. Vol. 37B - Proceedings of the 1991 Cryogenic Engineering Conference, Univ. of Alabama, Huntsville, June 11-14, 1991 (A93-48578 20-37); p. 1019-1027.
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  • 3
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    Cold-tip off-state conduction loss of miniature Stirling cycle cryocoolers (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: For redundant miniature Stirling-cycle cryocoolers in space applications, the off-state heat conduction down the coldfinger of one cooler is a parasitic heat load on the other coolers. At JPL, a heat flow transducer specifically designed to measure this load has been developed, and measurements have been performed on the coldfinger of a British Aerospace 80 K Stirling cooler with the tip temperature ranging between 40 and 170 K. Measurements have also been made using a transient warmup technique, where the warmup rates of the coldtip under various applied heat loads are used to determine the static conduction load. There is a difference between the results of these two methods, and these differences are discussed with regard to the applicability of the transient warmup method to a nonoperating coldfinger.
    Keywords: ENGINEERING (GENERAL)
    Type: In: Advances in cryogenic engineering. Vol. 37B - Proceedings of the 1991 Cryogenic Engineering Conference, Univ. of Alabama, Huntsville, June 11-14, 1991 (A93-48578 20-37); p. 1037-1043.
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  • 4
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    A mathematically simple turbulence closure model for attached and separated turbulent boundary layers (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 1684-169
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  • 5
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    Transonic separated flow predictions based on a mathematically simple, nonequilibrium turbulence closure model (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A mathematically simple, turbulence closure model designed to treat transonic airfoil flows even with massive separation is described. Numerical solutions of the Reynolds-averaged, Navier-Stokes equations obtained with this closure model are shown to agree well with experiments over a broad range of test conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-86826 , NAS 1.15:86826
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  • 6
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    Summary of all cycle II.5 shear and boundary layer measurements, aerodynamics (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The two measurement systems were used to measure mean velocity and velocity, mass flux, and total temperature fluctuations in the turbulent boundary on the fuselage of a KC-135 aircraft. The boundary layer thickness ranged between about 20 and 30 cm for the range of flight Mach numbers from about 0.25 to 0.85 and Reynolds numbers between 3 and 6 x 10 to the 6th power/m. The adaptation of each system for use in airborne applications is discussed. The data obtained from each system are given and compared with each other and they indicate that the two systems represent viable ones for use in future airborne turbulence experiments.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 459-464
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  • 7
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    Unsteady density and velocity measurements in the 6 foot x 6 foot wind tunnel (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The methods used and the results obtained in four aero-optic tests are summarized. It is concluded that the rather large values of density fluctuation appear to be the result of much higher Mach number than freestream and the violent turbulence in the flow as it separates from the turret. A representative comparison of fairing on-fairing off rms density fluctuation indicates essentially no effect at M = 0.62 and a small effect at M = 0.95. These data indicate that some slight improvement in optical quality can be expected with the addition of a fairing, although at M = 0.62 its effect would be nil. Fairings are very useful in controlling pressure loads on turrets, but will not have first order effects on optical quality. Scale sizes increase dramatically with increasing azimuth angle for a reprensentative condition. Since both scale sizes and fluctuation levels increase (total turbulence path length also increases) with azimuth angle, substantial optical degradation might be expected. For shorter wave lengths, large degradations occur.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 153-181
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  • 8
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    Reciprocating magnetic refrigerator (1985)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: A 4 to 15 K magnetic refrigerator to test as an alternative to the Joule-Thomson circuit as the low temperature stage of a 4 to 300 K closed-cycle refrigerator was developed. The reciprocating magnetic refrigerator consists of two matrices of gadolinium gallium garnet spheres located in tandem on a single piston which alternately moves each matrix into a 7 telsa magnetic field. A separate helium gas circuit is used as the heat exchange mechanism for the low and the high temperature extremes of the magnetic refrigerator. Details of the design and results of the initial refrigerator component tests are presented.
    Keywords: ENGINEERING (GENERAL)
    Type: NBS Proc. of the 3rd Cryocooler Conf.; p 33-41
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  • 9
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    Reciprocating magnetic refrigerator employing tandem porous matrices within a reciprocating displacer (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Disclosed is a method and apparatus for a magnetic refrigeration system. A continuously reciprocating displacer houses at least a pair of paramagnetic substances each of which is alternately driven into and out of a magnetic field. Two separate bidirectional pumping systems flow helium gas through the displacer and through both paramagnetic substances to create heat exchange conditions at two separate temperature extremes.
    Keywords: ENGINEERING (GENERAL)
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  • 10
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    A cold ejector for closed-cycle helium refrigerators (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The test results are presented of an initial cold helium ejector design that can be installed on a closed cycle refrigerator to provide refrigeration at temperatures below 4.2 K. The ejector, test apparatus, instrumentation, and test results are described. Tests were conducted both at room temperature and at cryogenic temperatures to provide operational experience with the ejector as well as for future use in the subsequent design of an ejector that will provide refrigeration at temperatures below 3 K.
    Keywords: ENGINEERING (GENERAL)
    Type: The Telecommunications and Data Acquisition Report; p 102-111
    Format: application/pdf
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