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  • Inorganic Chemistry  (7,251)
  • Aerodynamics
  • Fluid Mechanics and Thermodynamics
  • SPACE SCIENCES
  • 1985-1989  (3,464)
  • 1950-1954  (1,733)
  • 1945-1949  (763)
  • 1940-1944  (1,724)
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Keywords
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Years
Year
  • 1
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    An Experimental Investigation of Shear Layer Mixing in Supersonic Flows (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-26
    Description: In the design of a combustor, information is necessary for the mixing of the fuel and air in order to determine the optimum combustor length. In scramjet combustors the mixing often takes place in a shear layer that is formed between the fuel and air. This research was an experimental study of shear layers in supersonic flows aimed at determining what mechanisms affect the shear layer so that the mixing could be better predicted. A second goal was to provide sufficient instream information for use in checking existing Computational Fluid Dynamic (CFD) codes. The shear layer between a supersonic two-dimensional air stream (M = 2 or M = 3) was mixed with a near sonic two-dimensional air stream (M = 1.2). Instream measurements of pitot pressure and cone static pressure were used to determine mean velocity profiles at various axial locations. These velocity profiles were used to determine the shear layer spreading rate and are compared with various predictions. Wall measurements of static pressure, temperature and skin friction were also taken and are presented. The instream measurements were also used for comparison with an existing CFD code. The upstream velocity, pressure and temperature profiles were used as a starting profile and the code was used to calculate downstream profiles for comparison with the experimental results. Reasonable agreement between the measured and calculated results was obtained.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: CN-164-463
    Format: text
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  • 2
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    Second-Order Modeling of Low-Reynolds-Number Turbulence Near Walls (1989)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper presents a set of second-order closure models for low-Reynolds-number turbulence near the wall. Existing closure models for the Reynolds-stress equations were modified to show proper near-wall behavior. A dissipation-rate equation for the turbulent kinetic energy is also reformulated. The proposed models satisfy realizability and will not produce unphysical behavior. Fully developed channel flows are used for model testing. The equations are solved for the mean velocity, the Reynolds stresses, and the dissipation rate of the turbulent kinetic energy. The calculations are compared with both direct numerical simulations and with measurements. It is shown that the present models perform well in predicting the behavior of the turbulence near a wall. Significant improvements over previous models in predicting the components of the Reynolds stress tensor are obtained in the present models.
    Keywords: Fluid Mechanics and Thermodynamics
    Format: text
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  • 3
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    The Critical Role of Computational Fluid Dynamics in Rotary-Wing Aerodynamics (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-23
    Description: Helicopter rotor aerodynamics is basically the study of unsteady aerodynamic flows in a rotating and translating coordinate system. Current trends in this field are briefly reviewed by examining recent advances in lifting-surface theory, wake modeling, panel methods, and finite-difference models' Examples are used to illustrate selected current methods and some indications of promising future directions are highlighted.
    Keywords: Aerodynamics
    Type: Vertica (ISSN 0360-5450); Volume 11; Nos. 1, 2; 43-63
    Format: text
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  • 4
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    Helicopter Model Rotor-Blade Vortex Interaction Impulsive Noise: Scalability and Parametric Variations (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-23
    Description: Acoustic data taken in the anechoic Deutsch-Niederlaendischer Windkanal (DNW) have documented the blade-vortex interaction (BVI) impulsive noise radiated from a 1/7-scale model main rotor of the AH-1 series helicopter. Averaged model-scale data were compared with averaged full-scale, in-flight acoustic data under similar non-dimensional test conditions using an improved data analysis technique. At low advance ratios (mu = 0.164 - 0.194), the BVI impulsive noise data scale remarkably well in level, waveform, and directivity patterns. At moderate advance ratios (mu = 0.224 - 0.270), the scaling deteriorates, suggesting that the model-scale rotor is not adequately simulating the full-scale BVI noise. Presently, no proved explanation of this discrepancy exists. Measured BVI noise radiation is highly sensitive to all of the four governing nondimensional parameters--hover tip Mach number, advance ratio, local inflow ratio, and thrust coefficient.
    Keywords: Aerodynamics
    Type: Journal of the American Helicopter Society; Volume 32; No. 1; 3-12
    Format: text
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  • 5
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    Water Jetting (1985)
    In:  CASI
    Details
    Publication Date: 2018-06-09
    Description: Hi-Tech Inc., a company which manufactures water jetting equipment, needed a high pressure rotating swivel, but found that available hardware for the system was unsatisfactory. They were assisted by Marshall, which had developed water jetting technology to clean the Space Shuttles. The result was a completely automatic water jetting system which cuts rock and granite and removes concrete. Labor costs have been reduced; dust is suppressed and production has been increased.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1985; 85
    Format: application/pdf
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  • 6
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    Riblets for Stars and Stripes (1987)
    In:  CASI
    Details
    Publication Date: 2018-06-09
    Description: Stars and Stripes racing yacht brought the American's Cup back to the United States. Originating from NASA's drag reduction technology, the boats "secret weapon" was that the hull's underside was coated with riblets. Riblets are small, barely visible grooves on the surface of an airplane intended to reduce skin friction by smoothing the turbulent airflow next to the skin. Grooves are V-shaped with the angle pointing in the direction of the airflow. No deeper than a scratch, they have a pronounced beneficial influence on air turbulence. *No longer commercially available.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1987; 66-67
    Format: application/pdf
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  • 7
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    Flow Measurement (1988)
    In:  CASI
    Details
    Publication Date: 2018-06-09
    Description: Macrodyne, Inc.'s laser velocimeter (LV) is a system used in wind tunnel testing of aircraft, missiles and spacecraft employing electro optical techniques to probe the flow field as the tunnel blows air over a model of flight vehicle and to determine velocity of air and its direction at many points around the model. However, current state-of-the-art minicomputers cannot handle the massive flow of real time data from several sources simultaneously. Langley developed instrument Laser Velocimeter Autocovariance Buffer Interface (LVABI). LVABI is interconnecting instrument between LV and computer. It acquires data from as many as six LV channels at high real time data rates, stores it in memory and sends it to computer on command. LVABI has application in variety of research, industrial and defense functions requiring precise flow measurement.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Spinoff 1988; 87
    Format: application/pdf
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  • 8
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    Riblet Research (1985)
    In:  CASI
    Details
    Publication Date: 2018-06-09
    Description: Research at Langley on skin friction drag was described in Tech Briefs. 3M engineers suggested to Langley that grooves molded into a lightweight plastic film with adhesive backing and pressed on an airplane would be simpler than cutting grooves directly onto the surface. Boeing became involved and tested the "riblet" on an olympic rowing shell; the US won a silver medal. Based on the riblet-like projections on shark's skins, the technology may provide a 5 percent fuel saving for airplanes. Product is no longer commercially available.
    Keywords: Aerodynamics
    Type: Spinoff 1985; 66-67
    Format: application/pdf
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  • 9
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    Preliminary Results of Flight Tests of a Conventional Three-Blade Propeller at High Speeds (1942)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: As part of the program of flight tests of airplane propellers to determine compressibility effects at high speeds, preliminary flights have been made with a conventional three-blade propeller (Hamilton Standard 3155-6) on a Bell YP-39 airplane. This preliminary report presents the high-speed data obtained thus far with a brief analysis of the results.
    Keywords: Aerodynamics
    Format: application/pdf
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  • 10
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    Investigation of a 1/4-Scale Model of the Republic F-105 Airplane in the Langley 19-Foot Pressure Tunnel: Longitudinal Stability and Control of the Model Equipped with a Supersonic-Type Elliptical Wing-Root Inlet (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: No abstract available
    Keywords: Aerodynamics
    Type: NACA-RM-SL54F28
    Format: application/pdf
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