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  • 1
    Electronic Resource
    Electronic Resource
    Sobolev's Φ-function of radiative transfer in planar and spherical scattering media (1974)
    Springer
    Astrophysics and space science 28 (1974), S. 233-244 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In recent years Sobolev's Φ-function of radiative transfer has been discussed in connection with the resolvent of Milne's integral equation such that it plays an important role in the determination of the radiation field in semi-infinite (or finite) atmospheres with internal sources (cf. Sobolev, 1963). In the present paper, the part of Sobolev's Φ-function in plane-parallel and spherical, isotropically scattering, atmospheres with internal source distribution is investigated from analytical and numerical aspects. With the aid of invariant imbedding (cf. Bellmanet al., 1968), we computed Sobolev's Φ-function of Milne's integral equation for the planar case by solving the Cauchy system for the auxiliary function and Chandrasekhar'sX- andY-functions. The corresponding Φ-function for the spherical case is readily obtained from the for the planar case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00642253
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Sobolev's ?-function of radiative transfer in planar and spherical scattering media (1974)
    Springer
    Details
    Publication Date: 1974-05-01
    Print ISSN: 0004-640X
    Electronic ISSN: 1572-946X
    Topics: Physics
    Published by Springer
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    PAPER CURRENT
  • 3
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    Experimental simulation of latent heat thermal energy storage and heat pipe thermal transport for dish concentrator solar receiver (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Test results on a modular simulation of the thermal transport and heat storage characteristics of a heat pipe solar receiver (HPSR) with thermal energy storage (TES) are presented. The HPSR features a 15-25 kWe Stirling engine power conversion system at the focal point of a parabolic dish concentrator operating at 827 C. The system collects and retrieves solar heat with sodium pipes and stores the heat in NaF-MgF2 latent heat storage material. The trials were run with a single full scale heat pipe, three full scale TES containers, and an air-cooled heat extraction coil to replace the Stirling engine heat exchanger. Charging and discharging, constant temperature operation, mixed mode operation, thermal inertial, etc. were studied. The heat pipe performance was verified, as were the thermal energy storage and discharge rates and isothermal discharges.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: ASME PAPER 81-WA/SOL-34 , Winter Annual Meeting; Nov 15, 1981 - Nov 20, 1981; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Radiative cooling in shock-heated hydrogen-helium plasmas (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Axial and off-axis radiative cooling of cylindrical shock-heated hydrogen-helium plasmas is investigated theoretically and experimentally. The coupled fluid dynamic-radiative transfer equations are solved by a combination of approximation techniques aimed at simplifying the computation of the flux divergence term, namely, the quasi-isothermal approximation and the exponential approximation developed for the solid angle integration. The accuracy of the approximation schemes has been assessed and found acceptable for applying the methods to the rapid computation of the radiatively coupled flow problem. Radiative cooling experiments were conducted in a 6-inch annular arc accelerator shock tube (ANAA) for an initial pressure of 1 torr and shock speeds from 35 to 45 Km/sec. The results indicate that the lateral cooling is small compared with the axial cooling, and that better agreement is achieved between the data and the theoretical results by inclusion of the lateral temperature gradient.
    Keywords: PLASMA PHYSICS
    Type: Shock tube and shock wave research; Eleventh International Symposium; Jul 11, 1977 - Jul 14, 1977; Seattle, WA
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Optical analysis of Cassegrainian concentrator systems (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Cone optics procedures have been developed to treat optical systems employing multiple reflectors. The objective of the procedures is to develop efficient techniques to treat multiple reflections of cones when the secondary reflecting surface is curved - in fact, curved differently in different directions. The particular optical system under consideration is the Cassegrainian Concentrator System - a system consisting of a paraboloidal primary reflector and a confocal hyperboloidal secondary reflector. Multiple reflection cone optics methodology as well as preliminary results for the flux distributions and intercept factors based on it are presented in this paper. It is shown that neglecting local curvature effects of the secondary reflector, i.e. even in the differential solid angle within the sun's cone, may overestimate the peak of the flux distribution at the receiver aperture by a factor of two or more.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Sun II; May 28, 1979 - Jun 01, 1979; Atlanta, GA
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    NASA TECHNICAL REPORTS
  • 6
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    Curvature effects on stagnation radiative transfer in shock wave around blunt axisymmetric bodies (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: During hypersonic entry of a probe into the atmospheres of outer planets, the radiative energy transport in the shock-heated layer is of great significance in computing the heating to the heat shield. The so-called tangential slab approximation is frequently employed to evaluate the radiative flux to the surface of entry probes. A simple assessment of the accuracy of the tangential slab approximation at the stagnation point is given here for blunt axisymmetric bodies of various shock shapes which include spheres, paraboloids, hyperboloids and ellipsoids of different shock parameters.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 76-169 , Aerospace Sciences Meeting; Jan 26, 1976 - Jan 28, 1976; Washington, DC
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    NASA TECHNICAL REPORTS
  • 7
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    Equilibrium and nonequilibrium electron density measurements in transient shock-heated hydrogen-helium plasmas (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: In the NASA planetary program, atmospheric entry probe missions to Jupiter, Saturn, and Uranus are potential programs now being planned for the 1980's. The work reported in this paper is concerned with predicting the electron density, and resulting radiative emission from the shock layer which must be accommodated by the entry probe heatshield. Within the hydrogen-helium plasma surrounding the forward heatshield, there are regions of near thermochemical equilibrium whose properties are predictable - however, there are uncertainties in these electron density calculations necessitating further measurements by H-beta line broadening and holographic interferometer fringe shift as reported here. There is good agreement between the results obtained from the holographic measurements and the spectroscopic measurements which lends confidence to each of the two completely independent diagnostic techniques. The equilibrium electron density determined from the experimental measurements is somewhat higher than that predicted.
    Keywords: PLASMA PHYSICS
    Type: AIAA PAPER 76-121 , Aerospace Sciences Meeting; Jan 26, 1976 - Jan 28, 1976; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Energy transfer by radiation in non-grey atomic gases in isothermal and non-isothermal slabs (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A multiband model for the absorption coefficient of atomic hydrogen-helium plasmas is constructed which includes continuum and line contributions. Emission from 28 stronger lines of 106 that have been screened is considered, of which 21 are from hydrogen and 7 belong to helium, with reabsorption due to line-line, line-continuum overlap accurately accounted for. The model is utilized in the computation of intensities and fluxes from shock-heated slabs of 85% H2-15% He mixtures for slab thicknesses from 1 to 30 cm, temperature from 10,000 to 20,000 K, and for different densities. In conjunction with the multiband model, simple numerical schemes have been devised which provide a quick and comprehensive way of computing radiative energy transfer in nonisothermal and nongrey gases.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 75-702 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; May 27, 1975 - May 29, 1975; Denver, CO
    Format: text
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    NASA TECHNICAL REPORTS
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