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  • 1
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    Re-entrant groove heat pipe (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper describes theoretical and experimentally verified heat pipe characteristics of an axially grooved aluminum extrusion with a re-entrant groove profile. The extrusion is 13 mm diameter with 20 axial grooves, each groove consisting of a nominal .8 mm diameter channel with a .2 mm wide passageway connecting the channel to the hollow core. A computer program was written to compute the zero gravity heat transport capability of the extrusion. A heat pipe was fabricated and its performance characteristics measured. The characteristics of the pipe with ammonia at 20 C are: zero gravity pumping limit 143 w-meters; static wicking height 21.5 mm; evaporator and condenser coefficients 7300 and 20,500 watt/sq m C, respectively.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 77-773 , Thermophysics Conference; Jun 27, 1977 - Jun 29, 1977; Albuquerque, NM
    Format: text
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  • 2
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    Numerical turbulence modeling (1977)
    In:  CASI
    Details
    Publication Date: 2012-05-19
    Description: The underlying bases and developments in two techniques of detailed turbulence modeling are described where the flow is treated in the Eulerian sense, and one technique where the Lagrangian motions of vortices are followed. First, a technique is described for solving the single-point statistically averaged conservation equations. The Reynolds stresses that appear in these equations are evaluated by solving supplemental differential equations which contain terms that are modeled. A sequence of increasingly complex, but also increasingly general, modeling equations is described and computations based on these equations are compared with experimental data. The hierarchy of models described terminates with equations for the individual components of the Reynolds stress tensor. The second Eulerian technique approach to turbulence modeling is the direct numerical simulation of turbulent fields. In this approach, all three dimensional eddies between a predetermined range of sizes are computed in time within a specified volume of flow. Present day computers require a tradeoff between the size of the volume that can be considered and the degree of resolution of the turbulent eddies. Techniques of modeling the smallest eddies are described that permit enlarging the volume, or Reynolds number, that can be considered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Computational Fluid Dyn.; 37 p
    Format: text
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  • 3
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    Hot-wire anemometry in transonic flow (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The use of hot-wire anemometry for obtaining fluctuating data in transonic flows has been evaluated. From hot-wire heat loss correlations based on previous transonic data, the sensitivity coefficients for velocity, density, and total temperature fluctuations have been calculated for a wide range of test conditions and sensor parameters. For sensor Reynolds number greater than 20 and high sensor overheat ratios, the velocity sensitivity remains independent of Mach number and equal to the density sensitivity. These conditions were verified by comparisons of predicted sensitivities with those from recent direct calibrations in transonic flows. Based on these results, techniques are presented to obtain meaningful measurements of fluctuating velocity, density, and Reynolds shear stress using hot-wire and hot-film anemometers. Example of these measurements are presented for two transonic boundary layers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 15; Mar. 197
    Format: text
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  • 4
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    Monte Carlo turbulence simulation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper describes turbulence simulation experiments based on the principles of control system theory, that is, the construction of a system characterized by a system function such that upon exciting the system with prescribed noise processes the output of the system is a realization of a random processing the desired statistical attributes of turbulence. An experimental autocorrelation of Jimsphere measurements of wind velocity was approximated to simulate turbulent wind. From the approximate autocorrelation function, the required system function is obtained, and a discrete time system is designed. Another method of simulation is to solve the convolution integral by filter techniques. Other methods include discrete Fourier simulation and self-similar simulation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Format: text
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  • 5
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    Precision temperature gradient measurements on window glass (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Surface temperature gradients were measured with miniature thermocouples installed in a 58.5 cm (23-inch) square window. Test measurements at 25 locations were made under vacuum and with the window operating in radiant heat transfer mode. The analysis of thermocouple design and installation is presented along with a lead wire routing scheme to allow for both differential and absolute temperature measurements while using a minimum number of signal feedthru paths through the test chamber wall. Typical test data and operational precautions are presented along with the accuracy analysis for installation effects and measurement effects to support differential temperature measurement precision values of + or - 0.06 C RMS + or - 0.1 F RMS).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Goddard Space Flight Center Ninth Conf. on Space Simulation; p 5-14
    Format: application/pdf
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  • 6
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    Progress in the development of a Mach 5 quiet tunnel (1977)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Various techniques to control and reduce radiated noise and the application of these techniques to a 1/2-water Mach 5 quiet tunnel are reviewed. Measurements in a small scale nozzle have shown that the upstream part of the supersonic wall boundary layer could be maintained laminar up to Reynolds numbers of nearly 4 x 1 million based on the test region length upstream of the nozzle exit. Turbulent noise levels in this test region were then reduced by an order of magnitude. To maintain low noise levels at higher Reynolds numbers, laminar flow noise shields are required. Data are presented for shields that consist of small diameter rods alined nearly parallel to the entrance flow with small gaps between the rods for boundary layer suction. Analysis and data presented on the noise shielding and reflection characteristics of flat plates and a rod-wall test panel indicate that freestream turbulent noise can be reduced by 70 to 90 deg at high Reynolds numbers. Performance estimates for the 1/2-meter tunnel are based on these results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Laminar-Turbulent Transition; 14 p
    Format: text
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  • 7
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    Pressure and heating-rate distributions on a corrugated surface in a supersonic turbulent boundary layer (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Drag and heating rates on wavy surfaces typical of current corrugated plate designs for thermal protection systems were determined experimentally. Pressure-distribution, heating-rate, and oil-flow tests were conducted in the Langley Unitary Plan wind tunnel at Mach numbers of 2.4 and 4.5 with the corrugated surface exposed to both thick and thin turbulent boundary layers. Tests were conducted with the corrugations at cross-flow angles from 0 deg to 90 deg to the flow. Results show that for cross-flow angles of 30 deg or less, the pressure drag coefficients are less than the local flat-plate skin-friction coefficients and are not significantly affected by Mach number, Reynolds number, or boundary-layer thickness over the ranges investigated. For cross-flow angles greater than 30 deg, the drag coefficients increase significantly with cross-flow angle and moderately with Reynolds number. Increasing the Mach number causes a significant reduction in the pressure drag. The average and peak heating penalties due to the corrugated surface are small for cross-flow angles of 10 deg or less but are significantly higher for the larger cross-flow angles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1024 , L-11732 , NAS 1.60:1024
    Format: application/pdf
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  • 8
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    Accelerated life tests of specimen heat pipe from Communication Technology Satellite (CTS) project (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A gas-loaded variable conductance heat pipe of stainless steel with methanol working fluid identical to one now on the CTS satellite was life tested in the laboratory at accelerated conditions for 14 200 hours, equivalent to about 70 000 hours at flight conditions. The noncondensible gas inventory increased about 20 percent over the original charge. The observed gas increase is estimated to increase operating temperature by about 2.2 C, insufficient to harm the electronic gear cooled by the heat pipes in the satellite. Tests of maximum heat input against evaporator elevation agree well with the manufacturer's predictions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-73846 , E-9433
    Format: application/pdf
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  • 9
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    Two-Phase Working Fluids for the Temperature Range 50 to 350 C (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The decomposition and corrosion of two-phase heat transfer liquids and metal envelopes have been investigated on the basis of molecular bond strengths and chemical thermodynamics. Potentially stable heat transfer fluids for the temperature range 100 C to 350 C have been identified, and reflux heat pipes tests initiated with 10 fluids and carbon steel and aluminum envelopes to experimentally establish corrosion behavior and noncondensable gas generation rates.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-135255
    Format: application/pdf
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  • 10
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    A design handbook for phase change thermal control and energy storage devices (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Comprehensive survey is given of the thermal aspects of phase change material devices. Fundamental mechanisms of heat transfer within the phase change device are discussed. Performance in zero-g and one-g fields are examined as it relates to such a device. Computer models for phase change materials, with metal fillers, undergoing conductive and convective processes are detailed. Using these models, extensive parametric data are presented for a hypothetical configuration with a rectangular phase change housing, using straight fins as the filler, and paraffin as the phase change material. These data are generated over a range of realistic sizes, material properties, and thermal boundary conditions. A number of illustrative examples are given to demonstrate use of the parametric data. Also, a complete listing of phase change material property data are reproduced herein as an aid to the reader.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1074 , M-230
    Format: application/pdf
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