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  • 1
    Electronic Resource
    Electronic Resource
    Predicting Specific Volumes of Pure Polymers and VLE of Polymer Solutions by Group-Contribution Lattice Theory (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 707-717 
    Details
    ISSN: 1572-9567
    Keywords: lattice-hole theory ; polymer solutions ; specific volume ; vapor–liquid equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A generalized group-contribution (GC) scheme with an equation of state (EOS) presented previously by the present authors was extended to the prediction of specific volumes of pure polymers and vapor–liquid equilibria of polymer solutions. The GC-EOS requires only two parameters, representing group size and interaction between groups. A unique feature of the approach is that a single set of group information can be applied to predict both the configurational properties of pure polymers and mixtures in general. The approach was illustratively applied to the prediction of the density of pure polymers, vapor pressures of organic solvents, and phase equilibria of their polymer solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022618301397
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A new nonrandom lattice fluid model and its simplification by two-liquid theory for phase equilibria of complex mixtures (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 723-731 
    Details
    ISSN: 1572-9567
    Keywords: complex mixtures ; equation of state ; multiphase equilibria ; nonrandom lattice theory ; polymer solutions ; supercritical fluids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new riogorous equation of state (EOS) and its simplified version have been proposed by the present authors based on the full Guggenheim combinatorics ] of the nonrandom lattice hole theory. The simplified EOS. with the introduction of the concept of local composition, becomes similar to the density-dependent UNIQUAC model. However, im the present approach we have a volumetric EOS instead of the excess Gibbs function. Both EOSs were tested for their applicability in correlating the phase equilibria behavior of pure components and complex mixtures. Comparison of both models with experiment includes such systems as nonpolar nonpolar, nonpolar polar, and polar polar hydrocarbons, supercritical systems, and polymer solutions. With two parameters for each pure component and one binary interaction energy parameter, results obtained to date demonstrate that both formulations are quantitatively applicable to complex systems oer a wide range of temperatures, pressures, and concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01438857
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  • 3
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    Calculation of the rotor induced download on airfoils (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Interactions between the rotors and wing of a rotary wing aircraft in hover have a significant detrimental effect on its payload performance. The reduction of payload results from the wake of lifting rotors impinging on the wing, which is at 90 deg angle of attack in hover. This vertical drag, often referred as download, can be as large as 15 percent of the total rotor thrust in hover. The rotor wake is a three-dimensional, unsteady flow with concentrated tip vortices. With the rotor tip vortices impinging on the upper surface of the wing, the flow over the wing is not only three-dimensional and unsteady, but also separated from the leading and trailing edges. A simplified two-dimensional model was developed to demonstrate the stability of the methodology. The flow model combines a panel method to represent the rotor and the wing, and a vortex method to track the wing wake. A parametric study of the download on a 20 percent thick elliptical airfoil below a rotor disk of uniform inflow was performed. Comparisons with experimental data are made where the data are available. This approach is now being extended to three-dimensional flows. Preliminary results on a wing at 90 deg angle of attack in free stream is presented.
    Keywords: AERODYNAMICS
    Type: NASA, Ames Research Center, NASA Computational Fluid Dynamics Conference. Volume 1: Sessions 1-6; p 447-458
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Flow measurements of an airfoil with deflected spoiler (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Spoilers are used as an effective control surface in various stages of flight. The steady and unsteady flow characteristics change with incidence and spoiler angle. An experimental investigation is undertaken to understand the flow phenomena. Typical boundary layer and wake profiles at various incidences and spoiler angles are presented and discussed. A laminar separation is observed at low incidence and high spoiler angle. At incidence, a turbulent boundary layer develops and separation point moves downstream. Generally the wake profiles are asymmetric. When different length scales are used, the profiles become self-similar and symmetric. The importance of laser velocimetry in the reverse flow region is demonstrated by comparing the preliminary LDV measurements with the hot-wire results.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 83-0365 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 10, 1983 - Jan 13, 1983; Reno, NV
    Format: text
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  • 5
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    Unsteady wake measurements of an oscillating flap at transonic speeds (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The steady and unsteady wake profiles of an airfoil with an oscillating flap were measured at nominal free stream Mach number of 0.8 in the NASA Ames 11 x 11-foot wind tunnel. The instantaneous wake velocity and pressure profiles at four axial locations are presented up to one chord length from the trailing edge. Both fundamental harmonic frequency and typical time history data are presented to observe the effects of airfoil incidence and flap angle. The drag coefficient obtained from the wake pressure measurements is compared with that obtained from the airfoil pressure distribution.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 84-1563
    Format: text
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