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  • Other Sources  (11)
  • AERODYNAMICS  (7)
  • STRUCTURAL MECHANICS  (4)
  • 1980-1984  (11)
  • 1983  (8)
  • 1982  (3)
  • 1
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    Numerical calculation of nonlinear aerodynamics of wing-body configurations (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 864, Accession no. A83-21022
    Keywords: AERODYNAMICS
    Type: (ISSN 0001-1452)
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Status of NASA advanced LFC airfoil high-lift study (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The design of a high lift system for the NASA advanced LFC airfoil designed by Pfenninger is described. The high lift system consists of both leading and trailing edge flaps. A 3 meter semispan, 1 meter chord wing model using the above airfoil and high lift system is under construction and will be tested in the NASA Langley 4 by 7 meter tunnel. This model will have two separate full span leading edge flaps (0.10c and 0.12c) and one full span trailing edge flap (0.25c). The performance of this high lift system was predicted by the NASA two dimensional viscous multicomponent airfoil program. This program was also used to predict the characteristics of the LFC airfoils developed by the Douglas Aircraft Company and Lockheed-Georgia Aircraft Company.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 43-62
    Format: text
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  • 3
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    Convergence characteristics of nonlinear vortex-lattice methods for configuration aerodynamics (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Nonlinear panel methods have no proof for the existence and uniqueness of their solutions. The convergence characteristics of an iterative, nonlinear vortex-lattice method are, therefore, carefully investigated. The effects of several parameters, including 1) the surface-paneling method, 2) the integration method of the trajectories of the wake vortices, 3) vortex-grid refinement , and 4) the initial conditions for the first iteration on the computed aerodynamic coefficients and on the flow field details are presented. The convergence of the iterative-solution procedure is usually rapid. The solution converges with grid refinement to a constant value, but the final value is not unique and varies with the wing surface-paneling and wake-discretization methods within some range in the vicinity of the experimental result.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 83-1882
    Format: text
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  • 4
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    Propagation of crazing in viscoelastic media (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In response to a tensile stress glassy polymers exhibit crazing (surface cracks) which is a phenomenon of considerable practical and theoretical importance in the use of many plastics. An attempt is made to demonstrate how craze growth behavior is affected by the craze density (which is defined as the total number of crazes per unit surface area) surrounding the craze.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-173244 , NAS 1.26:173244
    Format: application/pdf
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  • 5
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    Stability, vibration and passive damping of partially restrained imperfect columns (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A theoretical and experimental study of slender tubular columns for possible use in space structures is conducted in the presence of partial rotational end restraints. Explicit formulas are derived for computing the buckling load and the lowest natural frequency of perfectly straight uniform elastic members with rotational end restraints possessing linear moment-rotation characteristics. An exact solution in the form of a transcendental equation, and a numerical solution using second-order finite-differences are also presented. The presence of an initial imperfection is also incorporated into the numerical procedure. Vibration tests are conducted on an imperfect tubular steel member in the absence of an axial load. A damping concept consisting of a string-mass assembly is explored. Three passive damping configurations involving combinations of three lead shots were investigated. The three lead shot configurations provided considerably greater damping than the single lead shot.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TM-85697 , NAS 1.15:85697
    Format: application/pdf
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  • 6
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    Flow improvements in the circuit of the Langley 4- by 7-meter tunnel (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The mean velocity profiles in both the horizontal and vertical planes of symmetry at specific locations throughout the tunnel circuit to identify the most promising means for improving the flow in the 4 by 7 meter wind tunnel were measured. In the base line tunnel flow surveys, the flow patterns near the end of the test section indicate a uniform mean velocity distribution. Downstream of the test section, unsymmetrical flow patterns result in low velocities along the inner walls and in flow separation along the inner wall of the diffuser upstream of the drive fan and along the outer wall of the large diffuser downstream of the drive fan. A set of trailing-edge flaps attached to the five flow-control vanes located just downstream of the first corner were installed. These flaps are successful in making the tunnel flow more symmetrical and in eliminating the regions of separation in the diffusers upstream and downstream of the drive fan.
    Keywords: AERODYNAMICS
    Type: NASA-TM-85662 , L-15631 , NAS 1.15:85662
    Format: application/pdf
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  • 7
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    On the three-dimensional vibrations of the cantilevered rectangular parallelepiped (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A solution is presented for the three-dimensional problem of determining the free vibration frequencies and mode shapes for a rectangular parallelepiped which is completely fixed on one face and free on the other five faces. This problem apparently is previously unsolved in the published literature. The Ritz method is used, with displacements assumed in the form of algebraic polynomials. Convergence is studied. Numerical results are given for the first five frequencies of each of the four symmetry classes of vibration, for five thick parallelepiped configurations, including the cube. Contour plots are exhibited for the modal displacements of the cube. The effects of varying Poisson's ratio are also observed.
    Keywords: STRUCTURAL MECHANICS
    Type: Acoustical Society of America, Journal (ISSN 0001-4966); 73; June 198
    Format: text
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  • 8
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    Study of NSI and related cable performance during tests performed in the NASA Hot Gas Facility (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Some seven different configurations of the NSI and other cables were tested in the NASA-MSFC Hot Gas Facility (HGF). The tests were conducted to study what happens to the cables when they are exposed to hot flow as was the case in the first two Shuttle flights, the STS-1 and STS-2. Protection of these components is vital for various functions especially to attain proper nozzle separation. The tests in the HGF demonstrated the severity of the aerodynamic forces combined with aero heating environment on the test cables and helped, in general, to evaluate the cable wrap materials and cable mounting hardware and technique. Blastape 2 cable wrap which is adequate for thermal protection of the cables must be properly clamped at its ends. The nylon clamps (or ties) used to secure cables to metal components inside the skirt could not withstand the heating. K5NA closeout material used on the outboard surface of the aft skirt when troweled over the cables performed excellently in protecting the cables and mounting hardware.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-170886 , NAS 1.26:170886 , LMSC-HREC-TM-D784644
    Format: application/pdf
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  • 9
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    The dynamic flexural response of propeller blades (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The determination of the torsional constants of three blade models having NACA four-digit symmetrical airfoil cross sections is presented. Values were obtained for these models analytically and experimentally. Results were also obtained for three other models having rectangular, elliptical, and parabolic cross sections. Complete modal analyses were performed for five blade models. The identification of modal parameters was done for cases when the blades were modeled as either undamped or damped multi-degree-of-freedom systems. For the experimental phase of this study, the modal testing was performed using a Dual Channel FFT analyzer and an impact hammer (which produced an impulsive excitation). The natural frequency and damping of each mode in the frequency range up to 2 kHz were measured. A small computer code was developed to calculate the dynamic response of the blade models for comparison with the experimental results. A comparison of the undamped and damped cases was made for all five blade models at the instant of maximum excitation force. The program was capable of handling models where the excitation forces were distributed arbitrarily along the length of the blade.
    Keywords: AERODYNAMICS
    Type: NASA-CR-169318 , NAS 1.26:169318
    Format: application/pdf
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  • 10
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    Flow mechanism and experimental investigation of a rotating stall in transonic compressors (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The flow characteristics of the rotating stall in compressors is studied, and a flow model is developed along with a theoretical calculation method based on vortex theory. A detailed theoretical calculation is completed for a two dimensional flow field in a transonic rotor in a rotating stall, and the result is in good agreement with experimental findings. The oscillograms of time-varying stall characteristic parameters recorded for the onset, growth, and cessation processes of rotating stall are analyzed, and some new flow phenomena deserving of further investigation are discovered. These include serious separation of individual blades, often preceding the onset of rotating stall in compressors with very small blade-camber angles, and periodical variation of the circumferential width of the stall cell with time, accompanied by periodical oscillation of the width of the stall cell in the radial direction of the blade. The circumferential and radial oscillation frequencies are the same.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77373 , NAS 1.15:77373
    Format: application/pdf
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