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  • 1
    ISSN: 1432-2153
    Keywords: Key words:Computational fluid dynamics, Shock tunnel, Blunt body, Hypersonic flow, Re-entry vehicle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract. Numerical and experimental techniques are used to model the flow and pressure distribution around the forebody of the HYFLEX hypersonic flight vehicle. We compare numerical simulation results with modified Newtonian theory and flight data to determine the accuracy of the computational fluid dynamics (CFD) technique used. The numerical simulations closely match the trends in flight data, and show that real gas effects have a small but significant influence on the nose pressure distribution. We also present pressure results from a scale-model tested in a shock tunnel, and compare them with simulation results. For the shock tunnel experiment, the model was placed such that part of the upper surface was in a region of the test flow where nonuniformities were significant, and it was shown that the numerical simulation could adequately capture these experimental flow features. The binary scaling parameter (describing the similarity in species dissociation between flight and model) was used to design the scale-model tests in the shock tunnel, and its effectiveness is discussed. We find that matching the flight Mach number in the shock tunnel experiment is not critical for reproducing flight pressure data, so long as flight velocity is matched, and binary scaling is maintained.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 98 (1995), S. 347-351 
    ISSN: 1434-6036
    Keywords: 24.70 ; 36.40 ; 67.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Short-lived ions12B (beta-radioactive, T1/2=20.3 ms) sustaining nuclear spin polarization were introduced into superfluid helium at 1.7 K. It was found that the12B ions were transported as charged entities under a static electric field and that the nuclear polarization was maintained throughout the lifetime of12B nuclei. Polarization of12B was determined through beta-NMR method. “Snowball”, a singly charged microcluster of helium atoms formed around an impurity ion, is responsible for the behaviour and thus constitutes a suitable environment for preserving nuclear polarization of the core ions12B. In a separate experiment snowballs were produced by implanting8Li (T1/2=830 ms) into liquid helium and detected by means of alpha particles from the core ions to guarantee that the snowballs survive longer than the lifetime of12B.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 23.60.+e ; 25.70.−z ; 27.80.+w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New neutron-deficient isotopes,197Rn,197mRn, and200Fr have been produced and identified on the basis of genetic correlations in the166Er(36Ar,5n)197Rn (Elab=186, 200 MeV), and169Tm(36Ar,5n)200Fr (Elab=186 MeV) reactions. The evaporation residues were separated from the beam by using a gas-filled recoil separator and implanted onto a position-sensitive solid-state detector. The α-decay energies (half-lives) of197Rn,197mRn and200Fr have been determined to be 7261±30 keV (51 −15 +35 ms), 7370±30 keV (18 −5 +9 ms), and 7500±3O keV, (570 −140 +270 ms), respectively.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A novel method was tried successfully to trap ions and to freeze out their nuclear polarization inside aggregates of helium atoms, “snowballs”, in superfluid helium. Spin polarized12B (T 1/2=20.4 ms) ions were introduced into superfluid helium and snowballs were created around the impinged impurity ions. Beta-ray asymmetry was measured to obtain the nuclear polarization of decaying12B. The comparison with the initial value of12B polarization produces that no relaxation in polarization was observed throughout lifetime of12B.
    Type of Medium: Electronic Resource
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