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  • Inorganic Chemistry  (693)
  • AERODYNAMICS  (626)
  • SPACE SCIENCES
  • 1995-1999
  • 1990-1994  (1,319)
  • 1985-1989
  • 1970-1974
  • 1990  (1,319)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1990-1994  (1,319)
  • 1985-1989
  • 1970-1974
Year
  • 1
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    International Hypersonic Waverider Symposium, 1st, University of Maryland, College Park, MD, Oct. 17-19, 1990, Proceedings (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The papers presented in this volume provide an overview of current theoretical and experimental research in the field of hypersonic waveriders. In particular, attention is given to efficient waveriders from known axisymmetric flow fields, hypersonic waverider design from given shock waves, limitations of waveriders, and aerodynamic stability theory of hypersonic waveriders. The discussion also covers momentum analysis of waverider flow fields, tethered aerothermodynamic research for hypersonic waveriders, simulation of hypersonic waveriders, and an idealized tip-to-tail waverider model.
    Keywords: AERODYNAMICS
    Type: International Hypersonic Waverider Symposium; Oct 17, 1990 - Oct 19, 1990; College Park, MD; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Proposed aerothermodynamic experiments in transition flow using the NASA/ASI tethered satellite system-2 (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: Aerothermodynamic, aerodynamic, and atmospheric science data acquired between 55 and 150 km has been limited by the lack of vehicles or platforms capable of sustained operation at these altitudes. Tethered satellites, which have been under study for this purpose by NASA, the Italian Space Agency (ASI), and others for more than a decade, are expected to become a reality by mid-1991. This approach, in which an instrumented platform is maintained at a desired altitude by a tether attached to a host vehicle orbiting at higher altitudes, will provide the first opportunity to obtain steady state data over an extended period encompassing one or more orbital revolutions. This paper describes the objectives and measurement methods for the first of the facility-class satellites, the TSS-2, which is proposed for a 1995 deployment, and gives the status of the experiment definition. Monte Carlo modeling of the flow fields at 130 km around the baseline 1.6 m diameter sphere is discussed and illustrative results of the modeling given.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-0536
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    NASA TECHNICAL REPORTS
  • 3
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    Second mode interactions in supersonic boundary layers (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: The nonlinear evolution of a two-dimensional second mode unstable wave in a Mach 4.5 wall-bounded flow is computed by solving the full time-dependent compressible Navier-Stokes equations. A highly accurate solution is obtained using spectral collocation methods. It is shown that departure from linearity first occurs in the critical layer due to the cubic nonlinearities in the momentum equation. This is a direct result of the large density perturbations in this regime. Time evolution studies of the growth rate as a function of normal distance from the plate suggests that the mode is evolving toward a nonlinear saturated state, and that this problem is possibly amenable to standard weakly nonlinear perturbation methods.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 4
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    On the Goertler vortex instability mechanism at hypersonic speeds (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: The linear instability of the hypersonic boundary layer on a curved wall is considered. As a starting point real-gas effects are ignored and the viscosity of the fluid is taken to be related to the temperature either by Chapman's Law or by Sutherland's Law. It is shown that the flow is susceptible to Goertler vortices. If Chapman's Law is used the vortices are trapped in the logarithmically thin adjustment layer in which the temperature of the basic flow changes rapidly to its free stream value and the nonuniqueness of the neutral stability curve associated with incompressible Goertler vortices is shown to disappear at high Mach numbers if the appropriate 'fast' streamwise dependence of the instability is built into the disturbance flow structure. If, on the other hand, Sutherland's Law is used, the vortices are found to spread into an O(1) region and the concept of a unique neutral stability curve is not tenable because of the nonparallel effects. For both laws the leading order terms in the expansions of the Goertler number are independent of the wave number and are due to the curvature of the basic state.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 5
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    Blunt-nosed swept supercritical LFC wings without nose flaps (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: To simplify the design of swept supercritical (SC) Laminar Flow Control (LFC) wings and maintain satisfactory low speed characteristics, blunt-nosed swept SC LFC wings without nose flaps and lower wing loadings were studied. Their boundary layer crossflow in the leading edge area is optimally controlled (1) by compensating the boundary layer crossflow of the front acceleration zone by an opposite crossflow in a downstream pressure rise area, (2) by maintaining a neutrally stable boundary layer crossflow by suction within a narrow spanwise suction strip located close to the wing attachment line in the front acceleration zone. The required suction massflow and power are then very small, especially considering the strongly stabilizing effect of surface and streamline curvature on crossflow stability.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 6
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    On the stability of swept wing laminar boundary layers including curvature effects (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: A linear stability analysis that encompasses curvature effects has been conducted in wind tunnel experiments on a swept NACA 64(2)-A015 wing, and published transition-onset results have been correlated with computed N-factor values. A strong stabilizing influence is noted upon the growth of the crossflow disturbance, when the flow is accelerated in regions of high body curvature. The maximum amplified crossflow disturbances were in all cases travelling waves; when TS waves reached their maximum, the N-factors at transition lay in the 9.9-13.8 range. Stabilization due to curvature effects was less pronounced in cases where acceleration occurred over a large portion of chord.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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  • 7
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    Experiments on swept-wing boundary layers (1990)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Three-dimensional boundary-layer experiments are currently being conducted on a 45-deg swept wing in the Arizona State University Unsteady Wind Tunnel. Crossflow-dominated transition is produced via a model with contoured end liners to simulate infinite swept-wing flow. Fixed-wavelength stationary and traveling crossflow vortices are observed. The stationary vortex wavelengths vary with Reynolds number as predicted by linear-stability theory, but with observed wavelengths which are about 25 percent smaller than theoretically predicted. The frequencies of the most amplified moving waves are in agreement with linear stability theory; however, traveling waves at higher frequencies than predicted are also observed. These higher-frequency waves may be harmonics of the primary crossflow waves generated by a parametric resonance phenomena. Boundary-layer profiles measured at several spanwise locations show streamwise disturbance profiles characteristic of the crossflow instability.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 8
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    Correlation of boundary layer stability analysis with flight transition data (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Recently, NASA completed a boundary-layer transition flight test on an F-14 aircraft which has variable-sweep capability. Transition data were acquired for a wide variety of sweep angles, pressure distributions, Mach numbers, and Reynolds numbers. In this paper, the F-14 flight test is briefly described and N-factor correlations with measured transition locations are presented for one of two gloves flown on the F-14 wing in the flight program; a thin foam and fiberglass glove which provided a smooth sailplane finish on the basic F-14, modified NACA 6-series airfoil. For these correlations, an improved linear boundary-layer stability theory was utilized that accounts for compressibility and surface and streamline curvature effects for the flow past swept wings.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 9
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    Transition research in low-disturbance high-speed wind tunnels (1990)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The technical requirements and test data from the Mach 3.5 Pilot Low-Disturbance Tunnel are presented. This unique facility provides a test region with essentially zero-acoustic noise and simulates, for the first time, the low-disturbance conditions of atmospheric flight. Applications to the test results of linear stability theory with the e exp N method indicate that transition locations for both simple and complex flows are well predicted by using N of about 9 to 11.
    Keywords: AERODYNAMICS
    Type: IUTAM Symposium on Laminar-Turbulent Transition; Sept. 11-15, 1989; Toulouse; France
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    NASA TECHNICAL REPORTS
  • 10
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    Numerical simulation of turbulent flows around airfoil and wing (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: During the last years the simulation of compressible viscous flows has received much attention. While the numerical methods were improved drastically, a satisfactory modeling of the Reynolds stresses is still missing. In this paper, after a short description of the numerical procedure used for solving the Reynolds equations, experiments with a promising simple turbulence model are discussed.
    Keywords: AERODYNAMICS
    Type: GAMM-Conference on Numerical Methods in Fluid Mechanics; Sept. 27-29, 1989; Delft; Netherlands
    Format: text
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    NASA TECHNICAL REPORTS
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