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  • AERODYNAMICS  (4,333)
  • 1995-1999  (99)
  • 1980-1984  (2,091)
  • 1975-1979  (2,110)
  • 1945-1949  (25)
  • 1940-1944  (8)
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  • 101
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    Vortex-flow aerodynamics - An emerging design capability (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Promising current theoretical and simulational developments in the field of leading edge vortex-generating delta, arrow ogival wings are reported, along with the history of theory and experiment leading to them. The effects of wing slenderness, leading edge nose radius, Mach number and incidence variations, and planform on the onset of vortex generation and redistribution of aerodynamic loads are considered. The range of design possibilities in this field are consequential for the future development of strategic aircraft, supersonic transports and commercial cargo aircraft which will possess low-speed, high-lift capability by virtue of leading edge vortex generation and control without recourse to heavy and expensive leading edge high-lift devices and compound airfoils. Attention is given to interactive graphics simulation devices recently developed.
    Keywords: AERODYNAMICS
    Type: Astronautics and Aeronautics; 19; May 1981
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  • 102
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    Longitudinal grooves for bluff body drag reduction (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Wind tunnel test results are presented for four axisymmetric bluff body configurations in order to determine their effect on form and pressure drag. It was found that drag reductions on the order of 40% are obtainable with an afterbody incorporating four longitudinal 'V' grooves. Although this effect may be due to the functioning of the grooves as longitudinal, continuous vortex generators, it is concluded that further research is needed to elucidate the physical basis of the test results. Optimization of the effect will be useful in base drag reduction for such vehicles as automobiles and cargo aircraft with sharply upswept afterbodies.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Apr. 198
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  • 103
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    Vectored injection into compressible laminar and turbulent boundary layers (1981)
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    Publication Date: 2011-08-18
    Description: A fundamental analysis of two-dimensional supersonic boundary layer flow, both laminar and turbulent, is presented for a wide range of normal and nonnormal mass-transfer velocities. The analysis is based on the numerical solution of the Navier-Stokes equations, and results are compared with available theoretical and experimental data. Certain cases of practical importance, for which results are not presently available, are referred to.
    Keywords: AERODYNAMICS
    Type: Computer Methods in Applied Mechanics and Engineering; 25; Jan. 198
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  • 104
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    Three-layer interactive method for computing supersonic laminar separated flows (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An interactive model for numerical computation of complicated two-dimensional flowfields including regions of reversed flow is proposed. The present approach is one of dividing the flowfield into three regions, in each of which a simplified mathematical model is applied: (1) outer, supersonic flow for which the full potential equation (hyperbolic) is used; (2) viscous, laminar layer in which the compressible boundary-layer model (parabolic) is used; and (3) recirculating flow modeled by the incompressible Navier-Stokes equations (elliptic). For matching of the numerical solutions in the three layers, two interaction models are developed: one for pressure interaction, the other for interaction between the shear layer and the recirculating flow. The uniform solution for the whole flowfield is then obtained by iteration of the local solutions under the constraints imposed by matching. The three-layer interactive model is used for solution of the flowfield past an asymmetric cavity. The method is shown to be capable of dealing with backflow without encountering problems at separation, characteristic to the boundary-layer approach.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 18; Nov. 198
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  • 105
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    Report of the panel on theoretical aerodynamics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Interactions between theoretical aerodynamics and the NTF are discussed. The development and validation of computational fluid dynamics computer codes, the determination of Reynolds number scaling laws, and extension of the data bases of entrainment type turbulence models to include high Reynolds number data are recommended areas of study. The major benefit theoretical aerodynamics could have on the NTF is in the quantitative description of wind tunnel wall interference effects.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 277-286
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  • 106
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    High Reynolds number research requirements for space vehicle design (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Requirements of entry vehicle design requiring high Reynolds number wind tunnel testing are discussed. The space shuttle orbiter, development of future space transportation systems, and planetary entry data analysis are considered.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 265-274
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  • 107
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    Report of the panel on aeroelasticity and unsteady aerodynamics (1981)
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    Publication Date: 2011-08-18
    Description: The status of recommended areas of study for the NTF are reviewed. Transonic and control surface unsteady aerodynamics, and buffet onset and loads are considered. Testing of dynamically scaled flutter models is discussed.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 237-246
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  • 108
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    Model experience in the Langley 0.3-m transonic cryogenic tunnel (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The model building, development, and testing experience gained during 8 years of operation of the 0.3-m Transonic Cryogenic Tunnel (TCT) is summarized. The summary is divided into four portions: (1) models tested in the 0.3-m TCT's original octagonal test section; (2) models tested in the present two dimensional test section; (3) models tested as a part of tunnel calibration and the development of advanced technology airfoils; and (4) development of a new way to construct two dimensional airfoil models. Design requirements imposed on the models by high Reynolds number testing at cryogenic temperatures are reviewed.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 53-73
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  • 109
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    Aerodynamic effects (1978)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The tethered satellite concept provides an ideal platform for the study of the interaction of the atmosphere with satellites of various shapes and surfaces under a wide range of flow conditions. From experiments which would measure the drag, lift, and torque acting on the tethered satellite, important information could be obtained which would have application to satellite lifetime prediction, determination of properties of the upper atmosphere, and scientific information on the interaction of high speed molecules with surfaces (the gas surface interaction). These experiments using the tethered satellite concept are described and would measure the following variables: angle of attack, surface roughness, and flow properties.
    Keywords: AERODYNAMICS
    Type: UAH(NASA Workshop on the Use of a Tethered Satellite System; p 151-155
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  • 110
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    Noise radiation from the side edges of flaps (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The recently observed phenomenon of high noise radiation from the side edges of flaps in flow is investigated by way of a simple two-dimensional model problem. The model is based upon a physical picture of boundary layer vorticity being swept around the edge by spanwise flow on the flap. The model problem is developed and solved and the resulting noise radiation calculated. Further, a mathematical condition for the vortex to be captured by the potential flow and swept around the edge is derived. The results show that the sound generation depends strongly upon the strength of the vorticity and distance from the edge and that it can be more intense than the more common trailing edge noise source in agreement with the experimental observations.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 18; May 1980
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  • 111
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    Stability aspects of diverging subsonic flow (1980)
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    Publication Date: 2011-08-17
    Description: The paper describes the computation of two-dimensional, subsonic, diverging internal flows and how they differ from the corresponding converging flows. Such diverging or decelerating flows occur in such obvious places as subsonic diffusers and inlets; however, such flows also occur in supersonic nozzles in the presence of a normal shock. The flow instability and its relation to the numerical method used, boundary conditions, and viscous effects are assessed both analytically and numerically. The inviscid flow is shown to be physically unstable and a poor representation of the true viscous flow.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 18; May 1980
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  • 112
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    Turbulence amplification in shock-wave boundary-layer interaction (1982)
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    Publication Date: 2011-08-18
    Description: Attention is directed to the acoustics research of the 1950s and 1960s for guidance in understanding and quantizing the turbulence amplification that can occur in regions of shock-wave boundary-layer interaction. Three primary turbulence amplifier-generator mechanisms are identified and shown, by linear analysis, to be responsible for turbulence amplification across a shock wave in excess of 100% of the incident turbulence intensity.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; July 198
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  • 113
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    Effectiveness of leading-edge vortex flaps on 60 and 75 degree delta wings (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of wind tunnel tests were run on 60 and 75 deg sweep delta wings to examine the effectiveness of leading-edge vortex flaps. Tests results showed that leading-edge vortex flaps are effective in giving large increases in lift-to-drag ratio and decreases in drag over a wide range of angle of attack. Tests on inverted flaps on the 60 deg delta wing showed substantial increases in lift and drag and may indicate a possibility of using inverted flaps on delta wings in the landing portion of flight. The 60 deg data were compared with that for a 75 deg sweep delta wing confirming that leading-edge vortex flap effectiveness is stronger as sweep is increased. Pitching moment effects due to vortex flaps use were also examined.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 18; Apr. 198
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  • 114
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    Partially confined multiple jet mixing (1981)
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    Publication Date: 2011-08-18
    Description: Results of hot-wire measurements in an incompressible partially confined jet issuing from an array of rectangular nozzles, equally spaced with their small dimensions aligned are presented. The quantities measured include mean velocity and the Reynolds stress in the two central planes of the jet at stations covering up to 115 widths (small dimension of a nozzle) downstream of the nozzle exit. For downstream distances greater than 60 widths, the flowfield is observed to be nearly homogenous and the turbulence appears to be quite similar to that of a grid generated turbulence.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 115
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    Unsteady Newton-Busemann flow theory. I - Airfoils (1981)
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    Publication Date: 2011-08-18
    Description: Newtonian flow theory for unsteady flow at very high Mach numbers is completed by the addition of a centrifugal force correction to the impact pressures. The correction term is the unsteady counterpart of Busemann's centrifugal force correction to impact pressures in steady flow. For airfoils of arbitary shape, exact formulas for the unsteady pressure and stiffness and damping-in-pitch derivatives are obtained in closed form, which require only numerical quadratures of terms involving the airfoil shape. They are applicable to airfoils of arbitrary thickness having sharp or blunt leading edges. For wedges and thin airfoils these formulas are greatly simplified, and it is proved that the pitching motions of thin airfoils of convex shape and of wedges of arbitrary thickness are always dynamically stable according to Newton-Busemann theory. Leading-edge bluntness is shown to have a favorable effect on the dynamic stability; on the other hand, airfoils of concave shape tend toward dynamic instability over a range of axis positions if the surface curvature exceeds a certain limit. As a byproduct, it is also shown that a pressure formula recently given by Barron and Mandl for unsteady Newtonian flow over a pitching power-law shaped airfoil is erroneous and that their conclusion regarding the effect of pivot position on the dynamic stability is misleading.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 116
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    Evidence of imbedded vortices in a three-dimensional shear flow (1981)
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    Publication Date: 2011-08-18
    Description: Vortex phenomena encountered in an investigation of the streamwise development of the three-dimensional wake region behind the tip of a three-dimensional wedge model are reported. Pressure profiles were measured by pitot probes downstream of a tip with a nearly constant surface pressure level and a nearly continuous surface curvature in a blowdown air tunnel operating at Mach 6. Rather than the simple three-dimensional quasi-parallel shear flow expected, the measurements indicated the presence of a flow with large deficits in longitudinal pitot pressure, which are usually associated with the core region of quasi-steady longitudinal vortices. Vapor screen flow visualizations also support the presence of longitudinal vortices located primarily in the tip region and evidently forming in the vicinity of the wake neck. An increase in overall wake thickness by 100% is also observed. The origin of the vortices as quasi-steady Taylor-Gortler vortices generated in the concavely curved shear layer near the wake neck is considered. It is pointed out that the existence of longitudinal vortexes suggests that three-dimensional turbulence modeling may be much more difficult than previously supposed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Mar. 198
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  • 117
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    Proposed aeroelastic and flutter tests for the National Transonic Facility (1981)
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    Publication Date: 2011-08-18
    Description: Tests that can exploit the capability of the NTF and the transonic cryogenic tunnel, or lead to improvements that could enhance testing in the NTF are discussed. Shock induced oscillation, supersonic single degree control surface flutter, and transonic flutter speed as a function of the Reynolds number are considered. Honeycombs versus screens to smooth the tunnel flow and a rapid tunnel dynamic pressure reducer are recommended to improve tunnel performance.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 153-161
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  • 118
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    Report of the wind tunnel/flight correlation panel (1981)
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    Publication Date: 2011-08-18
    Description: Basic calibration of the tunnel prior to conducting any tests, the areas requiring wind tunnel/flight test correlation for validating the NTF, and recommendations for achieving validation of the NTF are discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 249-262
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  • 119
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    High lift technology (1981)
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    Publication Date: 2011-08-18
    Description: The NASA Langley high lift technology program is reviewed and elements of the program which are considered Reynolds number sensitive are discussed. The Energy Efficient Transport (EET) and Supersonic Cruise Research (SCR) models proposed for high lift studies in the National Transonic Facility (NTF) are described. Recommendations regarding the NTF facility and test techniques are presented.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 197-213
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  • 120
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    Wall interference effects: Status review (1981)
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    Publication Date: 2011-08-18
    Description: The interference technology incorporated into the NTF design (hardware) and the emerging transonic wall interference assessment correction procedures (software) to be employed when the NTF becomes operational was reviewed. It is anticipated that the early experiments will provide data relevant to wall interference effects.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 123-241
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  • 121
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    Configuration aerodynamics (1981)
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    Publication Date: 2011-08-18
    Description: Static aerodynamic research related to aircraft configurations in their cruise or combat modes is discussed. Subsonic transport aircraft, transonic tactical aircraft, and slender wing aircraft are considered. The status and plans of Langley's NTF configuration research program are reviewed. Recommendations for near term configuration research are made.
    Keywords: AERODYNAMICS
    Type: High Reynolds Number Res. - 1980; p 217-234
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  • 122
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    Comments on Reynolds number effects and the role of NTF in the development of air vehicles (1981)
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    Publication Date: 2011-08-18
    Description: The National Transonic Facility (NTF) capability to match the full scale Reynolds numbers of all but the largest airplanes is discussed. Conversion factors to enable calculation of Sl-unit equivalents for all U.S. units are listed. Using data from several facilities, analytic methods, and flight test data, a competetive aircraft in the relatively low Reynolds number was developed. The NTF offers the capability to obtain data at full scale Reynolds numbers in the cruise condition for most of the products, and will be much closer than previous tunnels to full scale Reynolds number for the operating envelopes. It is primarily on the operating envelope that Reynolds number effects are most important and least predictable.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center High Reynolds Number Res. - 1980; p 143-148
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  • 123
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    Computational aerodynamics on large computers (1980)
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    Publication Date: 2011-08-17
    Description: Three examples of advances in computational aerodynamics; (1) three-dimensional inviscid transonic analysis, (2) design calculations for wings, and (3) the computation of viscous-induced aileron buzz, are reviewed. Attention is given to wing surface pressures, design optimization, computer memory, speed and advanced solution methods on parallel computer architecture. It is determined that many implicit approximate-factorization schemes, that have been developed for Navier-Stokes equations, can be coded to run efficiently on microprocessors.
    Keywords: AERODYNAMICS
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  • 124
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    Wing flapping with minimum energy (1980)
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    Publication Date: 2011-08-18
    Description: A technique employed by Prandtl and Munk is adapted for the case of a wing in flapping motion to determine its lift distribution. The problem may be reduced to one of minimizing induced drag for a specified and periodically varying bending moment at the wing root. It is concluded that two wings in close tandem arrangement, moving in opposite phase, would eliminate the induced aerodynamic losses calculated
    Keywords: AERODYNAMICS
    Type: Aeronautical Journal; 84; July 198
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  • 125
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    The effect of finite turbulence spatial scale on the amplification of turbulence by a contracting stream (1980)
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    Publication Date: 2011-08-17
    Description: The turbulence downstream of a rapid contraction is calculated for the case when the turbulence scale can have the same magnitude as the mean-flow spatial scale. The approach used is based on the formulation of Goldstein (1978) for turbulence downstream of a contraction, with the added assumptions of a parallel mean flow at downstream infinity and turbulence calculated far enough downstream so that the nonuniformity of the mean flow field has decayed, and by treating the inverse contraction ratio as a small parameter. Consideration is given to the large-contraction-ratio and classical rapid-distortion theory limits, and to results at an arbitrary contraction ratio. It is shown that the amplification effect of the contraction is reduced when the spatial scale of the turbulence increases, with the upstream turbulence actually suppressed for a contraction ratio less than five and a turbulence spatial scale greater than three times the transverse dimensions of the downstream channel.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 98; June 12
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  • 126
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    Types of leeside flow over delta wings (1980)
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    Publication Date: 2011-08-17
    Description: It is noted that so far most systematic investigations on the lee side flow over delta wings at supersonic speeds are concerned with flat upper surfaces. On the basis of these results, the paper makes an attempt to characterize the different types of flow over a wing with a delta-shaped upper surface by varying a number of parameters. It is concluded that the work should be considered a first step toward systematizing the flow over delta-shaped lee sides as well.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer Flugwissenschaften und Weltraumforschung; 4; Mar
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  • 127
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    Solution of the transonic full potential equation in conservative form using an implicit algorithm (1981)
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    Publication Date: 2011-08-18
    Description: The paper presents numerical solutions of the full potential equation in conservative form. The iteration scheme used is a fully implicit approximate factorization technique and provides a significant improvement in convergence speed relative to standard successive line overrelaxation algorithms. The spatial differencing algorithm is centrally differenced in both subsonic and supersonic regions to maintain stability. This effectively approximates rotated differencing, thereby greatly improving the reliability of the algorithm.
    Keywords: AERODYNAMICS
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  • 128
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    SPF/DB titanium concepts for structural efficiency foi HC (1982)
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation on superplastic forming/diffusion bonding titanium design concepts are presented. Sandwich skin panels with hat section, semicircular corrugation, sine wave, and truss cores are shown. The fabrication of wing panels is illustrated, and applications to the design of advanced variable sweep bombers summarized.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 95-110
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  • 129
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    SPF/DB titanium LFC porous panel concept (1982)
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation demonstrating superplastic forming/diffusion bonding titanium porous panels are presented. Fabrication phases, sandwich panels, load bearing qualities, microstructure, and panel surface after finishing are illustrated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 111-138
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  • 130
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    Computation of airfoil buffet boundaries (1981)
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    Publication Date: 2011-08-18
    Description: The ILLIAC IV computer has been programmed with an implicit, finite-difference code for solving the thin layer compressible Navier-Stokes equation. Results presented for the case of the buffet boundaries of a conventional and a supercritical airfoil section at high Reynolds numbers are found to be in agreement with experimentally determined buffet boundaries, especially at the higher freestream Mach numbers and lower lift coefficients where the onset of unsteady flows is associated with shock wave-induced boundary layer separation.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 19; Nov. 198
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  • 131
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    X-29A forward-swept-wing demonstrator airplane (1982)
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    Publication Date: 2011-08-18
    Description: The X-29A is a technology demonstrator. The FSW is just one of the technologies. Others include the following: discrete variable camber, relaxed static stability, triplex digital fly-by-wire (FBW) control system, variable-incidence/close-coupled canard, aeroelastically tailored composite wing, and thin supercritical airfoil. The growth potential for additional technologies is shown.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 177-189
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  • 132
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    Opportunities for wind-tunnel/flight correlation with new Boeing airplanes (1982)
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    Publication Date: 2011-08-18
    Description: The use of correlated data in airplane development is discussed. Areas of interest include initial airworthiness of an aircraft, low-speed configuration optimization, and high-speed configuration optimization. Data from wind tunnel tests are shown to be significant when applied to guarantee compliance, which includes fuel consumption, airspeeds, and takeoff and landing performance. The use of correlation in achieving FAA certification is also discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel-Flight Correlation, 1981; p 141-157
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  • 133
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    F-15 wind-tunnel/flight correlations (1982)
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    Publication Date: 2011-08-18
    Description: F-15 correlation data for longitudinal control and inlet-ramp effectiveness, and horizontal-tail setting for trim are presented. The Reynolds number effect on airfoil laminar bubble burst is included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 109-115
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  • 134
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    Wind-tunnel/flight correlation program on XB-70-1 (1982)
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    Publication Date: 2011-08-18
    Description: The XB-70-1 was selected for a wind-tunnel/flight correlation program as representative of a large, flexible supersonic airplane similar to a supersonic transport. Tests were made to determine the effects of control deflections, wing tip deflection, and variations in inlet mass flow (additive drag).
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 65-91
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  • 135
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    X-29A for NTF wind-tunnel/flight correlations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Considerations and recommendations for correlation are given. Basic tunnel calibration prior to research and development tests is suggested. Areas of concentration include: wing cruise drag and drag rise, wing separation and stall, afterbody and base drag, propulsion effects, vortex flows, cavity flows, and excrescences.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 191-197
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  • 136
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    Space-vehicle correlation of ground and flight experiments (1982)
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    Publication Date: 2011-08-18
    Description: A 2-percent-scale model was designed for testing in the NTF. This model has remotely controlled elevons, body flap, and rudder to minimize tunnel entries associated with configuration changes in the NTF. The Shuttle Orbiter has a very large aerodynamic data base obtained in ground facilities. Since the vehicle flight-test program has already begun, a large amount of flight data can be analyzed and correlated with the NTF results.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 173-176
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  • 137
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    Aerodynamic comparisons of Space Shuttle ascent: STS-1 flight versus wind-tunnel predictions (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is found from the comparisons that large longitudinal aerodynamic differences exist between wind tunnel predictions and flight measurements. Cold gas plume simulation underpredicted Shuttle base pressure. It is concluded that observed flight prediction increments are probably caused by several factors such as input error, independent variable errors, plume effects, and Reynolds number effects.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 133-140
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  • 138
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    Problems in correlation caused by propulsion systems (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Correlation efforts and selected results for transonic drag are reviewed. A process to reduce the typical error sources to decrease the errors inherent in the transonic aircraft development process is summarized.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 93-108
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  • 139
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    Wind-tunnel/flight-drag correlation (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Predicted and flight-test drag on the C-5A and the C-141 are correlated. Equivalent rigid flight-test profile drag and a rigid estimate based on wind tunnel data are also correlated. Correlations for the National Transonic Facility are included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 33-46
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  • 140
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    Review of the 1980 Wind-Tunnel/Flight Correlation Panel (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Wind tunnel/flight correlation history from the P-51 to the F-8 supercritical wing is reviewed, showing that researchers continue to be faced with nearly identical discrepancies in predicted versus measured drag. The capabilities of the National Transonic Facility to allow assessment of the effects which have heretofore plagued researchers and aircraft designers are anticipated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 23-32
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  • 141
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    Flow characteristics in an expansion tunnel as inferred from velocity measurements (1977)
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    Publication Date: 2011-08-17
    Description: A photoionization technique was used to study flow characteristics in an expansion tunnel. Vertical surveys of the axial component of flow velocity just downstream from the nozzle exit were obtained, and estimates of freestream density were inferred from the velocity measurement technique. The pitot pressure was measured and compared to the average axial component of velocity as a function of time for the two cases when air and CO2 were used as test gases. Vertical velocity and static density profiles at the nozzle exit are presented for the case when CO2 was used as test gas. Experimental results were used to determine the diameter and uniformity of the test core at the nozzle exit and the duration of the quasi-steady flow period. These data are relevant to evaluation of the suitability of operating an expansion tube as an expansion tunnel. The expansion tunnel is an expansion tube with a conical nozzle positioned at the exit of the acceleration section, so that nozzle entrance flow conditions are hypersonic and characterized by hypervelocity.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Sept
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  • 142
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    Low Reynolds number flow past a blunt axisymmetric body at angle of attack (1977)
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    Publication Date: 2011-08-17
    Description: Low Reynolds number flow of an ideal gas over a blunt axisymmetric body of large half-angle at small angles of attack is investigated, for the case of laminar hypersonic flow. Time-varying viscous shock layer equations describing the flowfield are obtained from the full Navier-Stokes system by keeping terms to second order in the inverse square root of Re in both viscous and inviscid regions; the equations are valid for moderate to high Re. Drag, skin friction, and heating rates were obtained at small (or zero) angles of attack. Conditions experienced by planetary entry probes during the high-altitude (early) legs of an atmospheric entry trajectory are pertinent to the problem.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Aug. 197
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  • 143
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    Evaluation of flight spoilers for vortex alleviation (1977)
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    Publication Date: 2011-08-17
    Description: The paper describes the facilities and test procedures used in a series of wind-tunnel and full-scale flight investigations of the effectiveness of flight spoilers currently existing on wide-bodied transport jet aircraft when used as trailing vortex hazard alleviation devices. Examples of the results of such studies include the variation of trailing wing rolling-moment coefficient with downstream distance behind a B-747 airplane model with various segments of its flight spoilers deflected 45 deg, and comparisons with models without spoilers deflected. It is concluded that the existing flight spoilers on the B-747 are effective as trailing vortex attenuators.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 14; Aug. 197
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  • 144
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    The effect of ablation injection on radiative and convective heating (1977)
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    Publication Date: 2011-08-17
    Description: A viscous shock-layer analysis for calculating high energy equilibrium flow fields about blunt axisymmetric bodies is applied to the problem of massive ablation injection with radiation transport. A nongray radiation model is used that accounts for both line and continuum radiation. The solution method is direct and provides both stagnation and downstream solutions. Results for shock heated air show that phenolic-nylon injection is substantially more effective in reducing the wall radiant flux than air injection. Also, for large included body angles, the wall radiative flux and the coupled phenolic-nylon injection rate do not continue to decrease with increasing distance downstream.
    Keywords: AERODYNAMICS
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  • 145
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    Comment on 'Drag coefficient of spheres in continuum and rarefied flows' (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A paper by Henderson (1976) provides a method of predicting experimental sphere drag data. This approach uses two equations for the drag coefficient, one for relative Mach number less than one, one for relative Mach number greater than 1.75. For relative Mach numbers between these limits a linear interpolation procedure is followed. In a comment on this paper, it is claimed, on the basis of comparing predictions with experimental results, that a method proposed by Walsh (1975) gives better predictions of the drag coefficient for relative Mach numbers less than 1.75, provided that a modification of the procedure is made for relative Mach numbers less than 0.1. For values over 1.75, both methods are considered equally accurate. In a reply to this comment, it is agreed that the Walsh method is more accurate when Reynolds numbers are within a range between 20 and 200, and Mach numbers are between 0.5 and 1.25. Presumed errors and possible limitations in the Walsh procedure for predicting drag coefficients are discussed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; June 197
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  • 146
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    Improved interactive calculation procedure for supersonic flows (1976)
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    Publication Date: 2011-08-17
    Description: An interactive numerical procedure has been developed for supersonic viscous flows (either two-dimensional or axisymmetric configurations). The flow field is divided into two regions: (1) an inner region which is highly viscous and mostly subsonic, and (2) an outer region where the flow is supersonic and in which viscous effects are small, but not negligible. This paper presents a detailed description of: I. Outer Region - numerical solution obtained by applying the method of characteristics to a system of equations which includes viscous and conduction transport terms only normal to the streamlines; II. Inner Region - treated by a system of equations of the boundary-layer type that includes higher order effects, such as longitudinal and transverse curvature and normal pressure gradients (equations are coupled and solved simultaneously in physical coordinates, using an implicit finite-difference scheme); III. Interactive Procedure - in the interaction mode, the two regions are coupled iteratively along a matching line, where the Mach number is of the order of 1.2.
    Keywords: AERODYNAMICS
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  • 147
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    Influence of nonconservative differencing on transonic streamline shapes (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A computer program recently developed by South and Brandt (1976) which contained the Murman (1973) conservative finite-difference scheme is easily modified to use the Garabedian and Korn (1971) nonconservative finite difference scheme. This program solves the transonic small disturbance equation for only symmetric flow, but incorporates several iterative solution techniques. Results are presented for the case where the equally spaced computational grid extended to infinity in both the streamwise and normal directions. Streamline shapes are obtained along several grid lines by a streamwise integration of the normal component of the perturbation velocity. Comparison cases are run for a 10% thick parabolic arc airfoil at zero incidence for freestream Mach numbers of 0, 0.70, 0.84, and 0.95. It is shown that the use of a nonconservative finite-difference scheme in transonic flow calculations destroys the global mass balance when shocks are present. This lack of mass balance may prove to be more crucial in the case of an unconfined external flow.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 14; Aug. 197
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  • 148
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    Vortex lattice prediction of subsonic aerodynamics of hypersonic vehicle concepts (1977)
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    Publication Date: 2011-08-17
    Description: The vortex lattice method introduced by Lamar and Gloss (1975) was applied to the prediction of subsonic aerodynamic characteristics of hypersonic body-wing configurations. The reliability of the method was assessed through comparison of the calculated and observed aerodynamic performances of two National Hypersonic Flight Research Facility craft at Mach 0.2. The investigation indicated that a vortex lattice model involving 120 or more panel elements can give good results for the lift and induced drag coefficients of the craft, as well as for the pitching moment at angles of attack below 10 to 15 deg. Automated processes for calculating the local slopes of mean-camber surfaces may also render the method suitable for use in preliminary design phases.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 14; Oct. 197
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  • 149
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    Cooling effectiveness of slot injection into a turbulent boundary layer (1977)
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    Publication Date: 2011-08-17
    Description: The cooling effectiveness of injection through multiple flush slots at an angle of 10 deg was studied experimentally in a wind tunnel. Air was injected from one to four slots into a turbulent Mach 6 boundary layer. The slot mass flow ratio is defined, and data which describe the dependence of the cooling effectiveness on the slot mass flow ratio are presented. Experimental values are indicated graphically for various cases of single and multiple slot injection, where the total mass injection (i.e., the sum of flow rates from each slot) is the same for each case. The results show that, for a given coolant mass flow rate, thermal protection over the maximum surface area can be accomplished best by injecting the coolant flow through multiple slots.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Sept
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  • 150
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    Vortex shedding from a blunt trailing edge with equal and unequal external mean velocities (1976)
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    Publication Date: 2011-08-16
    Description: A flow-visualization study has shown that strong Karman vortices develop behind the blunt trailing edge of a plate when the free-stream velocities over both surfaces are equal and that the vortices tend to disappear when the surface velocities are unequal. This observation provides an explanation for the occurence and disappearance of certain discrete tones often found to be present in the noise spectra of coaxial jets. Both the vortex formation and the tones occur at a Strouhal number based on the lip thickness and the average of the external steady-state velocities of about 0.2. Results from theoretical calculations of the vortex formation, based on an inviscid incompressible analysis of the motion of point vortices, were in good agreement with the experimental observations.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 75; June 25
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  • 151
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    Theoretical study of lift-generated vortex wakes designed to avoid rollup (1975)
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    Publication Date: 2011-08-16
    Description: Two hypothetical vortex wakes are introduced and studied theoretically to explore whether the rollup of lift-generated vortex sheets can be suppressed. The circulation distribution across each wake is specified such that one rotates and the other translates as a unit due to their self-induced velocities. Several span loadings are constructed from these solutions and the resulting inviscid wake structure is computed for several span lengths behind the generating wing by use of the discrete vortex method wherein the vortex wake is represented by an array of vortices. The final distribution of vortices is then used to estimate the rolling moment on an encountering wing. It is found that, even though the initial specified motions are not sustained, substantial reductions in rolling moment are predicted for certain ranges of the ratio of the span of the generating wing to the following wing.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Apr. 197
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  • 152
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    Numerical solutions for supersonic corner flow (1975)
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    Publication Date: 2011-08-16
    Description: Analytical solutions for inviscid supersonic corner flows are virtually nonexistent due to the complexity of the interference geometry. In view of this, numerical solutions for swept-compressive and swept-expansive corner flows are obtained. The governing equations are written in strong conservation-law form and are solved iteratively in nonorthogonal conical coordinates by use of a second-order, shock-capturing, finite-difference technique. The computed wave structure and surface pressure distributions are compared with high Reynolds number experimental data and show very good agreement. The results clearly show that supersonic corner flow at reasonably high Reynolds numbers including the effect of sweep is dominated by the inviscid field.
    Keywords: AERODYNAMICS
    Type: Journal of Computational Physics; 17; Feb. 197
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  • 153
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    Measured three-dimensional effects in transonic airfoil testing (1975)
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    Publication Date: 2011-08-16
    Description: An investigation was conducted regarding the issue of deviation from two-dimensionality in flowfield studies of a supercritical airfoil. It was found that significant three-dimensional effects occur in transonic airfoil tests, even for an aspect ratio of four. This is especially true at the supercritical Mach numbers, for which lateral propagation of disturbances is effective.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Feb. 197
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  • 154
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    Aerodynamic characteristics of the planetary atmosphere experiments test entry probe (1975)
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    Publication Date: 2011-08-16
    Description: The aerodynamic characteristics of the Planetary Atmosphere Experiments Test entry probe were determined experimentally in ballistic range tests over a wide range of Mach and Reynolds numbers, and were compared with full-scale flight results. The ground facility data agreed with the full-scale data within 2 to 3% in drag coefficient, and within 5 to 10% in static stability, at the higher Mach numbers. Comparisons of the flight data with conventional wind-tunnel data indicated a significant disagreement in drag coefficient in the transonic speed range suggestive of important sting or wall interference effects. Variations in drag coefficient with Mach number were very small hypersonically, but variations with Reynolds number were of the order of 15% at a free-stream Mach number of 13 over the Reynolds number range from 10,000 to 1,000,000. Variations in the lift and static-stability curves with Mach number and Reynolds number were also defined.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Jan. 197
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  • 155
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    Prospects for computational aerodynamics (1978)
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    Publication Date: 2011-08-17
    Description: The integral representations approach, for the solution of the Navier-Stokes equations is discussed as well as experience in its development and in applying available finite-difference and finite-element techniques to the treatment of three-dimensional problems, and the computation of turbulent flow. The magnitude of efforts required to develop turbulence models and three-dimensional algorithms indicates that the computational fluid dynamics research must have a broad base. Broader access to modern computing facilities that are in existence within NASA should be promoted for active researchers not directly affiliated with that agency.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Future Computer Requirements for Computational Aerodynamics; p 221-227
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  • 156
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    Modeling of the Reynolds stresses (1978)
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    Publication Date: 2011-08-17
    Description: In their most general form, the Reynolds averaged conservation equations result from ensemble or time averages of the instantaneous Navier-Stokes equations or their compressible counterparts. For these averaging processes to be consistent, the averaging time period must exceed the periods identified with the largest time scales of the turbulence, and yet be shorter than the characteristic times of the flow field. With these equations long period variations in the flow fields are deterministic, provided initial conditions are known. The average dependent variables are sufficiently smooth to be resolvable by finite difference techniques consistent with the size and speed of modern computers.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 239-247
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  • 157
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    Computational aerodynamics and the numerical aerodynamic simulation facility (1978)
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    Publication Date: 2011-08-17
    Description: Technical and economic reasons for accelerating the maturation of the discipline of computational aerodynamics include the cost of conducting the experiments required to provide the empirical data base for new aeronautical vehicles and the limitations in test facilities (Reynolds number, wall and support interferences, aeroelastic distortions, real-gas effects, etc.) for simulating the full-scale vehicle environment. General purpose computers do not have the necessary capability for the next stage of development. Solution of the three dimensional Reynolds averaged Naiver-Stokes equations in a short time to be practical for design purposes will require 40 times the power of current supercomputers. However, it is feasible to construct a special purpose processor that will meet these requirements to enhance the nation's aerodynamic design capability in the 1980's.
    Keywords: AERODYNAMICS
    Type: Future Computer Requirements for Computational Aerodynamics; p 5-30
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  • 158
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    Carbon vaporization into a nonequilibrium, stagnation-point boundary layer (1978)
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    Publication Date: 2011-08-17
    Description: The heat transfer to the stagnation point of an ablating carbonaceous heat shield, where both the gas-phase boundary layer and the heterogeneous surface reactions are not in chemical equilibrium, is examined. Specifically, the nonequilibrium changes in the mass fraction profiles of carbon species calculated for frozen flow are studied. A set of equations describing the steady-state, nonequilibrium laminar boundary layer in the axisymmetric stagnation region, over an ablating graphite surface, is solved, with allowance for the effects of finite rate of carbon vaporization.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
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  • 159
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    Perturbations in two- and three-dimensional transonic flows (1978)
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    Publication Date: 2011-08-17
    Description: The difficulty of treating the perturbation of transonic flow, during which shock waves change position, can be overcome by using a distorted coordinate system in which the locations of all shock waves do not change; the distortion is found as part of the solution. This device leads to a relation that allows a range of flows, with differing shock locations, to be related algebraically to two known 'calibration' flows. Results for flows around finite wings, including those with multiple, intersecting shock waves, are presented. A typical computing time for such examples is 0.3 sec on a CDC 7600 computer.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 16; July 197
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  • 160
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    Wall cooling effects on hypersonic transitional/turbulent boundary layers at high Reynolds numbers (1977)
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    Publication Date: 2011-08-17
    Description: The characteristics of a thick hypersonic boundary layer turbulent for a length of 175 cm on a 4 deg sharp wedge were measured. The resulting boundary layer was free from transverse curvature effects and only mildly affected by upstream history effects caused by pressure and wall temperature gradients. Heat-transfer distributions were used to locate regions of laminar, transitional, and turbulent flow at an edge unit Reynolds number of 470,000 cm at wall-to-total temperature ratios from about 0.3 to 1. Wall cooling had little effect on the location of the transition region. Pitot and total temperature profiles and skin-friction measurements were obtained at several locations along the model longitudinal centerline. Mixing length and turbulent Prandtl number distributions were derived from the fully turbulent mean profiles.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 15; Oct. 197
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  • 161
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    On the computation of two- and three-dimensional steady transonic flows by relaxation methods (1975)
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    Publication Date: 2011-08-16
    Description: The paper is concerned with the application of the Murman and Cole (1971) relaxation scheme to steady, inviscid transonic flow problems in two and three dimensions. This scheme, which automatically accounts for weak shock waves, uses separate difference operators in elliptic and hyperbolic regions. The details of the scheme are described in terms of the original small disturbance formulation of Murman and Cole. In particular, Murman's recent (1973) introduction of fully conservative difference operators to obtain the correct shock jumps is examined. The extension to treating the exact isentropic equation is then covered with special attention given to Jameson's (to appear) rotated difference scheme for supersonic flow regions. The bulk of the discussion is related to two-dimensional procedures, and some comparisons with experiment are made, with emphasis on the effects of viscosity and wind-tunnel walls. Application of the Murman-Cole scheme is then discussed for small disturbances in three dimensions.
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  • 162
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    Multiple slot skin friction reduction (1975)
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    Publication Date: 2011-08-16
    Description: The paper investigates analytically the effect of multiple slot injection on skin friction for a representative fuselage shape (ogive-cylinder body) and evaluates the potential of slot injection as a drag reduction system in subsonic flow. Typical CTOL cruise flight conditions (Mach number equals 0.82 at altitudes of 11 km) were adopted for a fuselage 67.06 m in length and with maximum diameter of 7.32 m. The numerical method of Price and Harris (1972) was used to calculate the boundary-layer characteristics up to the first slot, while the finite-difference method of Beckwith and Bushnell (1971) was used to calculate the velocity profile downstream of one, three, five, or ten slots. An integral expression is proposed for characterizing skin friction reduction effectiveness, and it is seen that large reductions in viscous drag (50%) are available through slot injection. Skin friction reduction is improved by increasing the number of injection slots but at a diminishing rate.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 163
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    Mach and Reynolds number effects on turbulent skin friction reduction by injection (1975)
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    Publication Date: 2011-08-16
    Description: The investigation reported is concerned with questions regarding a possible Mach number influence on skin friction reduction caused by injection. The investigation shows that data considered by Danberg (1967) for the no-blowing skin friction coefficient are in error. Accurate profiles and local skin friction coefficient values are obtained when the influence of low Reynolds number amplification in the outer region of the boundary layer is included in a calculation method.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Aug. 197
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  • 164
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    Cascade with subsonic leading-edge locus (1975)
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    Publication Date: 2011-08-16
    Description: The paper investigates a two-dimensional oscillating cascade with a subsonic leading edge locus in a supersonic flow. The blades are assumed to be of small thickness and camber, and are undergoing small amplitude-harmonic oscillations. The problem is reduced to the solution of a functional integral equation, and an expression is given for the kernel function.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Aug. 197
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  • 165
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    The flow over a 'high' aspect ratio gothic wing at supersonic speeds (1975)
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    Publication Date: 2011-08-16
    Description: Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.
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  • 166
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    On the analytic structure of the Taylor-Maccoll conical-flow solution (1975)
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    Publication Date: 2011-08-16
    Description: The conical flow solution for axisymmetric supersonic flow past cones has been found to be virtually independent of the ratio of specific heats when normalized in a certain way. A simple rational approximation to this flow is derived. The important singularities and the limiting behavior of the solution are also discussed.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer angewandte Mathematik und Physik; 26; July 25
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  • 167
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    Atmospheric entry into Jupiter's atmosphere in view of recent flyby results (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The paper examines the heating levels experienced by a probe entering Kliore's (1974) model of Jupiter's atmosphere and compares the results with those of the Jupiter model atmospheres given elsewhere (NASA SP-8069, 1971), with the heating levels of Tauber (1969) and Tauber and Wakefield (1971). The computations are made using a point-mass atmospheric entry trajectory program, i.e., the Allen-Eggers (1958) analysis and simple correlations of heating. Results of heating calculations are compared and discussed. It is found that the warm temperature bulge exists at a level too low in the atmosphere to affect any heating and that the nominal atmosphere fits Kliore's model atmosphere best insofar as heating is concerned. Previous estimates of the heating levels to be expected for a probe entering Jupiter's atmosphere are therefore unaffected by Kliore's postulated atmospheres.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 13; Feb. 197
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  • 168
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    Roughness induced transition criteria for space shuttle-type vehicles (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Tripping effectiveness of surface roughness on a delta wing shuttle orbiter model at 20 deg angle of attack is compared to that on plane and axisymmetrical bodies with and without longitudinal pressure gradients. The experimental data presented are compared on the basis of effective roughness Reynolds number since this parameter is not sensitive to flow conditions downstream of the roughness. The discussion covers the effective roughness Reynolds number as a function of roughness position Reynolds number, effective size ratio as a function of pressure gradient and distance from vehicle nose, and effect of spanwise roughness position on roughness effectiveness. It is shown that conventional criteria for sizing roughness elements which promote transition in two-dimensional zero-pressure gradient flows are insufficient for high-pressure gradient flows and three-dimensional flows. Roughness much smaller than that given by conventional criteria can cause transition and significantly increase the heating load.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 13; Feb. 197
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  • 169
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    Supersonic inlet contour interpolation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A method for designing supersonic inlet contours is described which consists in the interpolation of the contours of two known inlets designed for different Mach numbers, thereby determining the contours for a third inlet at an intermediate design Mach number. Several similar axisymmetric inlet contours were interpolated from known inlets with design Mach numbers ranging from 2.16 to 4.0 and with design Mach numbers differing by as much as 1.0. The flowfields were calculated according to Sorensen's (1965) computer program. Shockwave structure and pressure distribution characteristics are shown for the interpolated inlets. The validity of the interpolation is demonstrated by comparing the plots of the flowfield properties across the throat station of the interpolated inlet with the known inlets which were designed iteratively. It seems possible to write a computer program so that a matrix of known inlet contours can be interpolated.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 170
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    A complete second-order theory for the unsteady flow about an airfoil due to a periodic gust (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A uniformly valid second-order theory is developed for calculating the unsteady incompressible flow that occurs when an airfoil is subjected to a convected sinusoidal gust. Explicit formulas for the airfoil response functions (i.e., fluctuating lift) are given. The theory accounts for the effect of the distortion of the gust by the steady-state potential flow around the airfoil, and this effect is found to have an important influence on the response functions. A number of results relevant to the general theory of the scattering of vorticity waves by solid objects are also presented.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 74; Apr. 22
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  • 171
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    A technique for accelerating iterative convergence in numerical integration, with application in transonic aerodynamics (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A technique is described for the efficient numerical solution of nonlinear partial differential equations by rapid iteration. In particular, a special approach is described for applying the Aitken acceleration formula (a simple Pade approximant) for accelerating the iterative convergence. The method finds the most appropriate successive approximations, which are in a most nearly geometric sequence, for use in the Aitken formula. Simple examples are given to illustrate the use of the method. The method is then applied to the mixed elliptic-hyperbolic problem of steady, inviscid, transonic flow over an airfoil in a subsonic free stream.
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  • 172
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    Inlets for high angles of attack (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Different inlet designs for high angle of attack STOL and VTOL applications were tested in a subsonic wind tunnel. Three removable entry lips having contraction ratios of 1.30, 1.34 and 1.38 were tested with a single diffuser. The internal contour of each entry lip was an ellipse with a major to minor axis of 2.0. Each lip and diffuser assembly was tested to determine its tolerance to angle of attack, first with a conventional centerbody and then with an extended centerbody. Results indicate that a large improvement in separation angle (determined as a function of lip contraction ratio and inlet flow) was obtained for the extended centerbody for all contraction ratios. Improved inlet tolerance to angle of attack was obtained by reducing the adverse pressure gradient downstream of the throat.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 13; Apr. 197
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  • 173
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    Supersonic axisymmetric flow over boattails containing a centered propulsive jet (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 1358-136
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  • 174
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    A study of the aerodynamic interaction between a main rotor and a fuselage (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The wake of a helicopter rotor can have a significant effect on a fuselage. Results from a recent wind-tunnel investigation show that certain fuselage characteristics, normalized by rotor thrust, scale proportionally to a rotor-wake-induced velocity parameter. Effects on the body of changes in velocity, thrust, tip-path-plane angle of attack, and rotor/body position are discussed. These results show that the rotor can have a favorable or unfavorable influence on the body, depending upon the operating condition.
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  • 175
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    Applying slender wing benefits to military aircraft (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 545-559
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  • 176
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    Transonic pressure distributions on a rectangular supercritical wing oscillating in pitch (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 576-582
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  • 177
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    A new consistent spatial differencing scheme for the transonic full-potential equation (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 5, p. 585, Accession no. A83-16678
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 1027-103
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  • 178
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    Flow and heat transfer measurements along a cooled supersonic diffuser (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An experimental investigtion was conducted to ascertain the mean flowfield, including shock wave structure, separated flow regions, turbulent boundary-layer growth, static pressure variations, wall heat transfer, and shear stresses in a second-throat, axisymmetric, supersonic diffuser with wall cooling. The diffuser inlet Mach number of the heated air flow was 3.76, the stagnation pressure was 6.8 atm, the ratio of wall to total gas temperature was 0.44, and the diffuser discharged to the atmosphere. The complex flowfield involved deceleration and acceleration regions, supersonic and embedded subsonic regions, and strong viscous regions with relatively large radial and axial variations. The heat transfer and wall static pressure distributions were remarkably similar, and heat transfer rates were high locally at oblique shock/turbulent boundary-layer interactions, in the pseudoshock region, and in the separation region in the diffuser outlet section.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 777-780
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  • 179
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    Transonic-flow computation using an explicit-implicit method (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The explicit-implicit predictor corrector method of MacCormack (1981) is applied to the analysis of flows past airfoils. By comparing results obtained with different methods and meshes, it is shown that the above method provides, after certain modifications, reasonably good predictions of inviscid and viscous flows about an airfoil. Good results are also obtained for the transonic regime if the free-stream conditions are correct and if a suitable mesh is used.
    Keywords: AERODYNAMICS
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  • 180
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    On the convergence of unsteady generalized aerodynamic forces (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 12, p. 1923, Accession no. A81-29500
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 9921-8669); 21; 420-427
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  • 181
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    Heating distributions for a 0.006-scale Shuttle Orbiter over a range of hypersonic flow conditions (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 15, p. 2342, Accession no. A82-31855
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 21; 120-122
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  • 182
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    Overall aerodynamic performance of an annular flat-plate airfoil cascade (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 05, p. 588, Accession no. A83-16824
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 22; 250
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  • 183
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    On the impingement of supersonic jet on a normal flat surface (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An improved method, based on one strip approximation of the method of integral relations which was reported originally by Belov, Ginzburg and Shub (1973), is presented for the calculation of flow parameters in the impingement region of a supersonic, underexpanded jet striking a normal surface located within the first cell. The results are presented for two impingement conditions and found to be in good agreement with the experimental data.
    Keywords: AERODYNAMICS
    Type: Aeronautical Quarterly; 33; Aug. 198
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  • 184
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    Pressure distributions and shock shapes for a bent-nose biconic at incidence (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Initial results of a NASA study of the lift-drag characteristics of a 12.84/7 deg biconic model intended for airbraking during atmospheric entry of probes to Mars, Venus, Saturn, and Titan are reported. Pressure distributions and shock shapes were measured in the Langley 20 in. Mach 6 tunnel with the spherically blunted bent-nose model set at angles from 0-25 deg. Pressure distributions and shock shapes where computed using the STEIN flowfield code, which features a MacCormack scheme to integrate the three-dimensional Euler equations, the Rankine-Hugoniot jump conditions to model shock waves as discontinuities, and requires a supersonic condition at every step. A comparison was made between measured and predicted values. The leeward shock angle was found to be predictable to within 3% for all angles of attack, while parabolized Navier-Stokes equations are regarded as offering more accurate results than the STEIN code for surface pressure distributions.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 185
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    Chordwise and compressibility corrections for arbitrary planform slender wings (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Lomax and Sluder method for adapting slender-wing theory to delta or rectangular wings by making chordwise and compressibility corrections is extended to cover wings of any arbitrary planform in subsonic and supersonic flows. The numerical accuracy of the present work is better than that of the Lomax-Sluder results. Comparison of the results of this work with those of the vortex-lattice method and Kernel function method for a family of Gothic and arrowhead wings shows good agreement. A universal curve is proposed for the evaluation of the lift coefficient of a low aspect ratio wing of an arbitrary planform in subsonic flow. The location of the center of pressure can also be estimated.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 186
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    Numerical investigation of turbulent channel flow (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-30385)
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 118; May 1982
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  • 187
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    Wind-tunnel wall interference corrections for three-dimensional flows (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional aircraft configurations is presented. The Mach number and angle-of-attack corrections are obtained by numerically solving the Laplace equation in a parallelepiped with boundary conditions supplied mainly from experimental pressure measurements. A portion of these measurements and other wind-tunnel data required by the procedure may be replaced by theoretical estimates if not available from experiments. The accuracy of the correction results will then depend on the accuracy of these estimates. The correction procedure is applied to an isolated wing and to a wing-tail configuration in a solid-wall wind tunnel. It is found that neglecting twist and camber corrections for the wing effectively increases the tail angle-of-attack correction. Two different Mach number corrections can be calculated for the wing and tail. However, since only one Mach number correction is allowed for both the wing and the tail, and since the wing surface area is larger than the tail surface area, the final correction tends to be closer to the required wing correction. This is a source of error for the tail results.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; June 198
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  • 188
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    Validation of LTRAN2-HI by comparison with unsteady transonic experiment (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-29092)
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; May 1982
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  • 189
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    Large scale model measurements of airframe noise using cross-correlation techniques (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Cross-correlation techniques are used to measure the sound radiated by wing/flap airfoil configurations in the NASA-Ames 40 x 80 ft wind tunnel using a 6.7-m semispan model with three deployed flaps. The dominant source of flap noise is identified as the flap side edges, which exceeds that radiated by the midspan region by more than 10 dB. The turbulent surface eddies at the flap side edge have scales on the order of one-half the flap chord. The installation of flap actuator fairings at the flap side edge reduces the noise radiated from that location by 10 to 15 dB. The cross-correlation technique extracts airframe noise radiated by specific surface locations from the tunnel background noise, even when the noise is 25 dB higher than the measured airframe noise level.
    Keywords: AERODYNAMICS
    Type: Acoustical Society of America; vol. 71
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  • 190
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    Topological analysis of computed three-dimensional viscous flow fields (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Computed solutions of the time-dependent, Reynolds-averaged Navier-Stokes equations for three-dimensional flows having thin shear layers are analyzed, using topological concepts. Specific examples include the transonic flow over a body of revolution with conical afterbody at moderate angles of incidence to the free stream. Experimental flow-visualization techniques are simulated graphically to visualize the computed flow. Scalar and vector fluid dynamic properties, such as pressure, shear stress, and vorticity on the body surface, are presented as topological maps, and their relationship to one another in terms of orientation and singular points is discussed. The extrapolation from these surface topologies toward the understanding of external flow-field behavior is discussed and demonstrated.
    Keywords: AERODYNAMICS
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  • 191
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    Injection slot location for boundary-layer control in shock-induced separation (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 18, p. 726, Accession no. A78-41866
    Keywords: AERODYNAMICS
    Type: (ISSN 0021-8669)
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  • 192
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    Comprehensive missile aerodynamics programs for preliminary design (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 12, p. 1851, Accession no. A82-27106
    Keywords: AERODYNAMICS
    Type: (ISSN 0022-4560)
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  • 193
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    Equivalent angle-of-attack method for estimating nonlinear aerodynamics of missile fins (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 19, p. 2971, Accession no. A82-39113
    Keywords: AERODYNAMICS
    Type: (ISSN 0022-4560)
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  • 194
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    Aerodynamics of wraparound fins (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 863, Accession no. A83-21011
    Keywords: AERODYNAMICS
    Type: (ISSN 0022-4560)
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  • 195
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    Numerical calculation of nonlinear aerodynamics of wing-body configurations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 864, Accession no. A83-21022
    Keywords: AERODYNAMICS
    Type: (ISSN 0001-1452)
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  • 196
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    Benchmark determination of Shuttle Orbiter entry aerodynamic heat-transfer data (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 965, Accession no. A82-19777
    Keywords: AERODYNAMICS
    Type: (ISSN 0022-4560)
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  • 197
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    Computation of high Reynolds number internal/external flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously cited in issue 17, p. 2878, Accession no. A81-39001)
    Keywords: AERODYNAMICS
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  • 198
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    An unstructured-grid software system for solving complex aerodynamic problems (1995)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A coordinated effort has been underway over the past four years to elevate unstructured-grid methodology to a mature level. The goal of this endeavor is to provide a validated capability to non-expert users for performing rapid aerodynamic analysis and design of complex configurations. The Euler component of the system is well developed, and is impacting a broad spectrum of engineering needs with capabilities such as rapid grid generation and inviscid flow analysis, inverse design, interactive boundary layers, and propulsion effects. Progress is also being made in the more tenuous Navier-Stokes component of the system. A robust grid generator is under development for constructing quality thin-layer tetrahedral grids, along with a companion Navier-Stokes flow solver. This paper presents an overview of this effort, along with a perspective on the present and future status of the methodology.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Research Center, Surface Modeling, Grid Generation, and Related Issues in Computational Fluid Dynamic (CFD) Solutions; p 289-308
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  • 199
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    Calculated effects of varying Reynolds Number and dynamic pressure on flexible wings at transonic speeds (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A computational method is described that includes the effects of static aeroelastic wing deflections in steady transonic aerodynamic calculations. This method, known as the Transonic Aero-elastic Program System (TAPS), interacts a 3D transonic computer code with boundary layer and a linear finite element structural analysis codes to calculate wing pressures and deflections. The nonlinear nature of the transonic flow makes it necessary to couple the aerodynamic and structures codes in an iterative manner. TAPS has been arranged in a modular fashion so that different aerodynamic or structures programs may be used with a minimum of coding changes required. Results obtained using two different aerodynamic codes in TAPS are given, and those results are correlated with experimental data.
    Keywords: AERODYNAMICS
    Type: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1 (date]; 19 p
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  • 200
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    Sensitivity analysis in computational aerodynamics (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Information on sensitivity analysis in computational aerodynamics is given in outline, graphical, and chart form. The prediction accuracy if the MCAERO program, a perturbation analysis method, is discussed. A procedure for calculating perturbation matrix, baseline wing paneling for perturbation analysis test cases and applications of an inviscid sensitivity matrix are among the topics covered.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 10 p
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