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  • AERODYNAMICS  (4,201)
  • 1980-1984  (2,091)
  • 1975-1979  (2,110)
  • 1
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    Multidomain approach for calculating compressible flows (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A multidomain approach for calculating compressible flows by using unsteady or pseudo-unsteady methods is presented. This approach is based on a general technique of connecting together two domains in which hyperbolic systems (that may differ) are solved with the aid of compatibility relations associated with these systems. Some examples of this approach's application to calculating transonic flows in ideal fluids are shown, particularly the adjustment of shock waves. The approach is then applied to treating a shock/boundary layer interaction problem in a transonic channel.
    Keywords: AERODYNAMICS
    Type: NASA-TM-76692 , NAS 1.15:76692
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  • 2
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    Current developments lighter than air systems (1981)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Lighter than air aircraft (LTA) developments and research in the United States and other countries are reviewed. The emphasis in the U.S. is on VTOL airships capable of heavy lift, and on long endurance types for coastal maritime patrol. Design concepts include hybrids which combine heavier than air and LTA components and characteristics. Research programs are concentrated on aerodynamics, flight dynamics, and control of hybrid types.
    Keywords: AERODYNAMICS
    Type: NASA-TM-84744 , NAS 1.15:84744
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  • 3
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    Experimental investigation of the flow on the suction side of a thin Delta wing (1981)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Surface oil flow patterns were photographed and pressure distribution measurements were carried out on a sharp edged delta wing of aspect ratio lambda = 1.0 in order to determine the influence of Reynolds number and of vortex breakdown on the flow on the suction side of the wing. The formation of the secondary vortex occurs due to separation of a laminar boundary layer in the front part of the wing and due to separation of a turbulent boundary layer in the rear part of the wing. In the case of turbulent separation, the secondary separation line is closer to the wing leading edge than in the laminar case. The position of the transition depends on the Reynolds number and on the angle of incidence. The breakdown of a vortex above the wing leads to a kink in the secondary separation line.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75897
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  • 4
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    The influence of a high pressure gradient on unsteady velocity perturbations in the case of a turbulent supersonic flow (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The amplification or reduction of unsteady velocity perturbations under the influence of strong flow acceleration or deceleration was studied. Supersonic flows with large velocity, pressure gradients, and the conditions in which the velocity fluctuations depend on the action of the average gradients of pressure and velocity rather than turbulence, are described. Results are analyzed statistically and interpreted as a return to laminar process. It is shown that this return to laminar implies negative values in the turbulence production terms for kinetic energy. A simple geometrical representation of the Reynolds stress production is given.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75236 , AAF-NT-79-10 , Colloq. d''Aerodynamique Appl.; Nov 07, 1978 - Nov 09, 1978; Marseille; France|Jul 01, 1979
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  • 5
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    Unsteady effects of a control surface in two dimensional subsonic and transonic flow (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The experimental results of steady and unsteady pressure measurements, carried out in subsonic and transonic flow on a 16 percent relative thickness supercritical aerofoil, equipped with a trailing edge flap involving 25 percent of the chord, in a sinusoidal motion are given. These experimental results are compared with those obtained by various methods of steady and unsteady inviscid flow calculations. Some calculation results in which viscous effects have been taken into account, for both steady and unsteady flows, are also presented.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75775 , AGARD-CP-262
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  • 6
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    On the swelling of rolled up vortex surfaces and the breakdown of the vortex core for slender wings (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Simplified models of the vortex distribution over cylindrical surfaces are developed. The effect of a change of vortex strength was analyzed quantitatively by menas of potential theory. The considerable bulging of the cylindrical vortex sheet as a consequence of the change of the vortex strength is discussed. The coiling-up of the vortices rotation in opposite directions over the cylindrical surface renders the condition for instability and the subsequent large spreading of the vortex core. These processes occur without a positive pressure gradient being necessary in the field of flow surrounding the coiled up vortex sheet.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75862
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  • 7
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    Investigations regarding the drag characteristics of flow-disturbing bodies which are arranged in line and attached to the wall (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The flow characteristics of rectangular bodies mounted on the base area of a rectangular closed wind tunnel are investigated. As many as four bodies are mounted in line with equal distances between successive bodies. The Mach number of the flowing air is in the range from 0.1 to 0.5. Total and individual drag values could be charged within a wide range by a suitable selection of the distance between successive bodies.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75788
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  • 8
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    On wings of circular design (1979)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Prandtl's method of sources and sinks for air foils is used to investigate the aerodynamics of circular wings in constant flow. Lift distribution, total lift, and pitching moment are investigated as well as the influence of changes in the angle of attack.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75505
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  • 9
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    Solution of a few nonlinear problems in aerodynamics by the finite elements and functional least squares methods (1979)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The numerical simulation of the transonic flows of idealized fluids and of incompressible viscous fluids, by the nonlinear least squares methods is presented. The nonlinear equations, the boundary conditions, and the various constraints controlling the two types of flow are described. The standard iterative methods for solving a quasi elliptical nonlinear equation with partial derivatives are reviewed with emphasis placed on two examples: the fixed point method applied to the Gelder functional in the case of compressible subsonic flows and the Newton method used in the technique of decomposition of the lifting potential. The new abstract least squares method is discussed. It consists of substituting the nonlinear equation by a problem of minimization in a H to the minus 1 type Sobolev functional space.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75732
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  • 10
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    Aerodynamics on a transport aircraft type wing-body model (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The DFLR-F4 wing-body combination is studied. The 1/38 model is formed by a 9.5 aspect ratio transonic wing and an Airbus A 310 fuselage. The F4 wing geometrical characteristics are described and the main experimental results obtained in the S2MA wind tunnel are discussed. Both wing-fuselage interferences and viscous effects, which are important on the wing due to a high rear loading, are investigated by performing 3D calculations. An attempt is made to find their limitations.
    Keywords: AERODYNAMICS
    Type: NASA-TM-76878 , NAS 1.15:76878
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  • 11
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    NASA/HAA Advanced Rotorcraft Technology and Tilt Rotor Workshops. Volume 3: Aerodynamics and Structures Session (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Advanced rotorcraft technology and tilt rotor aircraft were discussed. Rotorcraft performance, acoustics, and vibrations were discussed, as was the use of composite materials in rotorcraft structures. Rotorcraft aerodynamics, specifically the aerodynamic phenomena of a rotating and the aerodynamics of fuselages, was discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TM-84147 , Dec 02, 1980 - Dec 05, 1980; Palo Alto, CA; United States
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  • 12
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    The aerodynamics of small Reynolds numbers (1980)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Aerodynamic characteristics of wing model gliders and bird wings in particular are discussed. Wind tunnel measurements and aerodynamics of small Reynolds numbers are enumerated. Airfoil behavior in the critical transition from laminar to turbulent boundary layer, which is more important to bird wing models than to large airplanes, was observed. Experimental results are provided, and an artificial bird wing is described.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75816 , Jahrbuch 1953 der Wiss. Ges. fuer Luftfahrt E. V. mit den Vortraegen der WGL-Tagung in Goettingen; May 26, 1953 - May 29, 1953; Braunschweig; Germany
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  • 13
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    Rain and deicing experiments in a wind tunnel (1983)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Comments on films of tests simulating rain and ice conditions in a wind tunnel are presented, with the aim of studying efficient methods of overcoming the adverse effects of rain and ice on aircraft. In the experiments, lifesize models and models of the Mirave 4 aircraft were used. The equipment used to simulate rain and ice is described. Different configurations of landing and takeoff under conditions of moderate or heavy rain at variable angles of incidence and of skipping and at velocities varying from 30 to 130 m/sec are reproduced in the wind tunnel. The risks of erosion of supersonic aircraft by the rain during the loitering and approach phases are discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77077 , NAS 1.15:77077 , May 29, 1967 - May 31, 1967; Paris
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  • 14
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    Separation behavior of boundary layers on three-dimensional wings (1981)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: An inverse boundary layer procedure for calculating separated, turbulent boundary layers at infinitely long, crabbing wing was developed. The procedure was developed for calculating three dimensional, incompressible turbulent boundary layers was expanded to adiabatic, compressible flows. Example calculations with transsonic wings were made including viscose effects. In this case an approximated calculation method described for areas of separated, turbulent boundary layers, permitting calculation of this displacement thickness. The laminar boundary layer development was calculated with inclined ellipsoids.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75877
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  • 15
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    Study of the vortex conditions of wings with large sweepback by extrapolation of the Jones method (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The pockets of separation originating on the leading edges are surrounded by vortex sheets. Their configuration and intensity were determined by four conditions with the JONES approximation, which is itself corrected by a simple logic. Field pressures and stresses were computed for different cases and are compared with test results (pure deltas, swallow tails, truncations, strakes, ducks, fuselage).
    Keywords: AERODYNAMICS
    Type: NASA-TM-75863 , Symp. of Appl. Aerodynamics; Nov 13, 1979 - Nov 15, 1979; Lille; France
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  • 16
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    A study of dirigibles for use in the Peruvian Selva Central region (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The potential for dirigibles as transports in the Selva Central region of Peru was evaluated by means of a mission and economic analysis. A total requirement to transport over 19 million tons (t) of agricultural produce, lumber and meat was projected by the year 2004. A primary route involving zones for loading and delivering this carbo was identified. Although dirigibles are capable of short field operation, all existing airfields must be enlarged in width to allow for all conditions of wind and weather and to provide space for overnight mooring. A maintenance base and operations headquarters, complete with hangar and other service facilities would be required. The quantities of cargo capacities of 5 to 100 tons were identified. Fleet sizes up to 106 dirigibles (in 20 t capacities) would be required. Dirigibles were assumed to be of the nonrigid type except in the 100 t category for which rigid characteristics were assumed. A method of determining dirigible costs was developed. The values derived were then applied to an economic analysis to determine initial investment and operating costs. It was found that larger dirigibles of approximately 20 t capacities or higher could offer significant cost benefits over airplanes, provided cruise speeds were higher than 100km/hr.
    Keywords: AERODYNAMICS
    Type: NASA-TM-85634 , NAS 1.15:85634
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  • 17
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    Some characteristic quantities of Karman-Trefftz profiles (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: For von Karman-Trefftz profiles, the characteristics which determine profile shape (profile nose dimensions, maximum thickness and position: tail slope and curvature) are stated as a function of transformation variables using the Timman method. The profile is obtained by iterative deformation of a von Karman profile with known transformation, corresponding as well as possible to the desired profile. The figures and relations which enable a good choice of the required profile are given.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77013 , NAS 1.15:77013
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  • 18
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    The calculation of separated flow at helicopter bodies (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: For abstract see A81-47555.
    Keywords: AERODYNAMICS
    Type: NASA-TM-76715 , NAS 1.15:76715
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  • 19
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    Lee side flow for slender delta wings of finite thickness (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: An experimental and theoretical investigation carried out to determine the lee side flow field over delta wings at supersonic speeds is presented. A theoretical method to described the flow field is described, where boundary conditions as a result of the experimental study are needed. The computed flow field with shock induced separation is satisfactory.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75753 , ILR-23
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  • 20
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    A finite element method for the computation of transonic flow past airfoils (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A finite element method for the computation of the transonic flow with shocks past airfoils is presented using the artificial viscosity concept for the local supersonic regime. Generally, the classic element types do not meet the accuracy requirements of advanced numerical aerodynamics requiring special attention to the choice of an appropriate element. A series of computed pressure distributions exhibits the usefulness of the method.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75749 , MBB-UFE-1352-0
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  • 21
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    Application of a numerically generated orthogonal coordinate system to the solution of inviscid axisymmetric supersonic flow over blunt bodies (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A numerically generated orthogonal coordinate system (with the body surface and shock wave as opposite boundaries) was applied with a time asymptotic method to obtain steady flow solutions for axisymmetric inviscid flow over several blunt bodies including spheres, paraboloids, ellipsoids, hyperboloids, hemisphere cylinders, spherically blunted cones, and a body with a concavity in the stagnation region. Comparisons with experimental data and with the results of other computational methods are discussed. The numerically generated orthogonal coordinate system is described and applications of the method to complex body shapes, particularly those with concave regions, are discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1619 , L-13353
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  • 22
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    Aircraft icing: Introduction (1979)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: The objectives of the Workshop were as follows: (1) to assess the current understanding of fixed wing and rotorcraft operational icing environments and problems (2) to evaluate facilities requirements for R&D and certification purposes (3) to examine means of improving icing forecasts (4) to identify shortcomings in aeronautical icing knowledge which can be alleviated by new research and instrumentation development.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; 3 p
    Format: text
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  • 23
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    Practical calculation of laminar and turbulent bled-off boundary layers (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Bleed-off of boundary layer material is shown to be an effective means for reducing drag by conserving the laminar boundary layer and preventing separation of the turbulent boundary layer. The case in which the two effects of bleed-off overlap is examined. Empirical methods are extended to the case of bleed-off. Laminar and turbulent boundary layers are treated simultaneously and the approximation differential equations are solved without an uncertain error. The case without bleed-off is also treated.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75328
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  • 24
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    Effect of the properties of a porous coating on boundary layer stability (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Drawing off gas from the boundary layer is a well-known method for increasing the stability of boundary layers. The increase in stability is primarily connected with a change in the velocity profile form in the case of suction. On the basis of the assumption that the velocity perturbations on a porous slate do not equal zero, the influence of the properties of a permeable surface upon the boundary layer stability were studied.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75235
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  • 25
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    Experimental studies on the influence of the degree of turbulence and of a turbulence thread on the compressible subsonic flow through flat compressor cascades (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The measurements revealed that at low Reynolds numbers the profile loss is considerably reduced both by the increased degree of turbulence and by a turbulence thread, while it is somewhat increased at high Reynolds numbers, and that a profile loss reduction is connected with an increase in deflection and in pressure shift. The turbulence generator is most effective on the one hand in the middle of the operating range of the cascades, and on the other at very high Mach numbers together with a large angle of incidence.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75276
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  • 26
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    A finite volume method for calculating transonic potential flow around wings from the pressure minimum integral (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Analysis of the pressure minimum integral in the calculation of three-dimensional potential flow around wings makes it possible to use non-rectangular mesh networks for distributing the three-dimensional potential into discrete points. The method is comparatively easily expanded to the treatment of realistic airplane configurations. Shock-pressure affected pressure distributions on any wings are determined with accuracy using this method.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75324
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  • 27
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    Measurement of the turbulence intensity behind a two-dimensional cascade and in a three-stage axial blower (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Turbulence intensity (Tu) measurements were made in two-dimensional and rotating cascades of blades in a low-speed cascade wind tunnel using hot-wire probes as sensors. The local Tu at Re = 1.6x100000 was determined in the wake zone behind a two-dimensional cascade. Then the values were recomputed for a rotating cascade, giving a mean turbulence intensity of 6.5% at 1/10 chord downstream and 2.9% at one chord. Fans were used for measurements on the rotating cascade. Re was equal to 7x100000. Frequency analysis was employed to separate the actual Tu of the entry flow from the effects caused by interaction with the rotor blades, showing that the true Tu increased from a few tenths of a percent to 6.6% in the 1st rotor, and from 7.2 to 9.3% in the 2d rotor. The Tu behind the 3d rotor was equal to 8.9%.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75275
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  • 28
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    Methods and results of boundary layer measurements on a glider (1978)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Boundary layer measurements were carried out on a glider under natural conditions. Two effects are investigated: the effect of inconstancy of the development of static pressure within the boundary layer and the effect of the negative pressure difference in a sublaminar boundary layer. The results obtained by means of an ion probe in parallel connection confirm those results obtained by means of a pressure probe. Additional effects which have occurred during these measurements are briefly dealt with.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75294
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  • 29
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    Summary of experimentally determined facts concerning the behavior of the boundary layer and performance of boundary layer measurements (1978)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: A summary report of boundary layer studies is presented. Preliminary results of experimental measurements show that: (1) A very thin layer (approximately 0.4 mm) of the boundary layer seems to be accelerated; (2) the static pressure of the outer flow does not remain exactly constant through the boundary layer; and (3) an oncoming boundary layer which is already turbulent at the suction point can again become laminar behind this point without being completely sucked off.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75270
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  • 30
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    Airfoil profile in a nonuniform flow (1978)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: A theory of airfoil section past two dimensional nonuniform flow is developed. The theory is based on representation of airfoil section by vortex and source distributions and it can be used for calculation of aircraft wings in homogeneous and inhomogeneous flow, as well as for calculation of straight and radial blade and vane-cascades.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75272
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  • 31
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    Transonic flow past an airfoil with condensation (1978)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: In connection with investigations conducted to determine the influence of water vapor on experiments in wind tunnels, the question arose as to what changes due to vapor condensation might be expected in airfoil measurements. Density measurements on circular-arc airfoils aided by an interferometer in choked tunnels with parallel walls show that increasing humidity produces increasing changes in the flow field. The flow becomes nonstationary at high humidity. At the airfoil, however, the influence of the condensation is only felt, inasmuch as the shock bounding the local supersonic region moves upstream with increasing humidity while its intensity decreases. The density distribution upstream of the shock remains unchanged. Even if the flow becomes nonstationary in the vicinity of the airfoil, no changes occur at the airfoil.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75201
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  • 32
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    Turbulence modeling of shock separated boundary-layer flows (1977)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Computations of transonic and hypersonic shock-separated boundary-layer flows using zero-equation (algebraic), one-equation (kinetic energy), and two-equation (kinetic energy plus length scale) turbulence eddy viscosity models are described and compared with measurements. The computations make use of a new Navier-Stokes computer algorithm that has reduced computing times by one to two orders of magnitude. The algorithm, and how the turbulence models are incorporated into it, are described. Results for the transonic flow show that the unmodified one-equation model is superior to the zero-equation model in skin-friction predictions. For the hypersonic flow, a highly modified one-equation model that accurately predicts surface pressure and heat transfer is described. Preliminary two-equation model results are also presented.
    Keywords: AERODYNAMICS
    Type: Symposium on Turbulent Shear Flows; Apr 18, 1977 - Apr 20, 1977; University Park, PA
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  • 33
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    Computation of unsteady transonic flows by the indicial method (1977)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The indicial method is investigated for the computation of unsteady transonic force and moment coefficients for use in flutter analyses. This approach has the advantage that solutions for all reduced frequencies for a given mode of motion can be obtained from a single finite-difference flowfield computation. Comparisons of indicial and time-integration computations for oscillating airfoil and flap motions help define limits on the motion amplitude for the applicability of the indicial method to transonic flows. Within these limits, solutions for various motion modes can be superposed to obtain solutions for multiple-degree-of-freedom aeroelastic systems. Also, a simple aeroelastic problem is solved by an alternative approach in which the structural motion and flowfield equations are integrated simultaneously using a time-integration finite-difference procedure.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 77-447 , Mar 24, 1977 - Mar 25, 1977|Conference on Structures, Structural Dynamics and Materials; Mar 21, 1977 - Mar 23, 1977; San Diego, CA; US
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  • 34
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    Measurement of unsteady pressures in rotating systems (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The principles of the experimental determination of unsteady periodic pressure distributions in rotating systems are reported. An indirect method is discussed, and the effects of the centrifugal force and the transmission behavior of the pressure measurement circuit were outlined. The required correction procedures are described and experimentally implemented in a test bench. Results show that the indirect method is suited to the measurement of unsteady nonharmonic pressure distributions in rotating systems.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75445 , DLR-FB-77-34
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  • 35
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    Design of a transonically profiled wing (1978)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The application of well known design concepts with the combined use of thick transonic profiles to aircraft wing design was investigated. Optimization in terms of weight and operational costs was emphasized. It is shown that the usual design criteria and concepts are too restricted and do not sufficiently represent the physical processes over the wing. Suggestions are made for improving this situation, and a design example given. Compared with a wing design according to previously used criteria, the new design is found to be superior in the most important functions. It is concluded that an isobar concept adjusted to the planform in conjunction with an 'organically' designed wing will lead to the weight optimum solutions of wing profiles.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75440 , PAPER-77-026 , Jahrestagung, Deutsche Ges fuer Luft- und Raumfahrt; Sep 13, 1977 - Sep 15, 1977; Berlin
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    Flutter analysis of a glider made of synthetic materials (1977)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A description of the flutter behavior of the Standard Cirrus is given. Steady vibration tests were conducted, and vibration and flutter calculations were made.
    Keywords: AERODYNAMICS
    Type: NASA-TM-75160
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  • 37
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    On the flow processes in sharply inclined and stalled airfoils in parallel movement and rotation (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The purpose of this study is to obtain a deeper insight into the complicated flow processes on airfoils in the region of the buoyancy maxima. To this end calculated and experimental investigations are carried out on a straight stationary, a twisted stationary and a straight rotating rectangular wing. According to the available results the method gives results which can be applied sufficiently for flow applied firmly on all sides for all rotation values. The reliability of the method may be questioned for a flow undergoing transition from the attached to the separated state or for totally separated flow and higher rotation values.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77509 , NAS 1.15:77509
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  • 38
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    A new method of evaluating the side wall interference effect on airfoil angle of attack by suction from the side walls (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A quantitative evaluation method of the suction effect from a suction plate on side walls is explained. It is found from wind tunnel tests that the wall interference is basically described by the summation form of wall interferences in the case of two dimensional flow and the interference of side walls.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77722 , NAS 1.15:77722 , NAL-TR-680
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  • 39
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    A possibility of avoiding surface roughness due to insects (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Discussion of a method for eliminating turbulence caused by the formation of insect roughness upon the leading edges and fuselage, particularly in aircraft using BLC. The proposed technique foresees the use of elastic surfaces on which insect roughness cannot form. The operational characteristics of highly elastic rubber surface fastened to the wing leading edges and fuselage edges are examined. Some preliminary test results are presented. The technique is seen to be advantageous primarily for short-haul operations.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77419 , NAS 1.15:77419 , Feb 01, 1963 - Feb 28, 1963; Junin; Argentina
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  • 40
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    Experimental determination of the inertia constants of an airplane or of a missile (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The possibility to measure the inertia constants of an airplane or of a missile by a unique experimental set up without having to materialize axes of rotation was investigated. It is sufficient to suspend the structure appropriately, to obtain the six natural modes determined by the suspension and to introduce these results as data into a computer. If the structure is very flexible it is necessary to take into account the first natural modes of deformation. Experiments on rigid and flexible models led to precise results and allow consideration of full scale measurements. The final goal is to provide, by a standard ground vibration test completed by the measured characteristics of the suspension modes, the set of data necessary for flutter calculations and for the determination of all the inertia constants.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77767 , NAS 1.15:77767
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  • 41
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    Kasprzyk airfoil. The first wind-tunnel tests (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The Kasprzyk slotted flap glider airfoil (the Kasper wing) enabling glider flight at 32 km/h and 0.5 m/sec descent speed was wind tunnel tested in the U.S. The test layout is described and reasons offered for discrepancies between wind tunnel results and Polish in flight data: high induced drag caused by relative size of model wing span and tunnel, by vortex attenuators on the model and their proximity to the tunnel wall, nonsimilarity between flow over a smooth wing and flow over the Kasprzyk wing with bound vortices, obstruction of the tunnel test chamber cross section by the model wing, discrepant Reynolds numbers, and model airfoil aspect ratio much smaller than the prototype. The overall results offer partial confirmation of the Kasprzyk theory, but further in tunnel and in flight studies are recommended.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77757 , NAS 1.15:77757
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  • 42
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    Analysis of airfoil transitional separation bubbles (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A previously developed local inviscid-viscous interaction technique for the analysis of airfoil transitional separation bubbles, ALESEP (Airfoil Leading Edge Separation) has been modified to utilize a more accurate windward finite difference procedure in the reversed flow region, and a natural transition/turbulence model has been incorporated for the prediction of transition within the separation bubble. Numerous calculations and experimental comparisons are presented to demonstrate the effects of the windward differencing scheme and the natural transition/turbulence model. Grid sensitivity and convergence capabilities of this inviscid-viscous interaction technique are briefly addressed. A major contribution of this report is that with the use of windward differencing, a second, counter-rotating eddy has been found to exist in the wall layer of the primary separation bubble.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3791 , NAS 1.26:3791
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  • 43
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    Cold-air performance of compressor-drive turbine of department of energy upgraded automobile gas turbine engine. 3: Performance of redesigned turbine (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The aerodynamic performance of a redesigned compressor drive turbine of the gas turbine engine is determined in air at nominal inlet conditions of 325 K and 0.8 bar absolute. The turbine is designed with a lower flow factor, higher rotor reaction and a redesigned inlet volute compared to the first turbine. Comparisons between this turbine and the originally designed turbine show about 2.3 percentage points improvement in efficiency at the same rotor tip clearance. Two versions of the same rotor are tested: (1) an as cast rotor, and (2) the same rotor with reduced surface roughness. The effect of reducing surface roughness is about one half percentage point improvement in efficiency. Tests made to determine the effect of Reynolds number on the turbine performance show no effect for the range from 100,000 to 500,000.
    Keywords: AERODYNAMICS
    Type: NASA-TM-83627 , E-2044 , DOE/NASA/50194-39 , NAS 1.15:83627 , USAAVSCOM-TR-84-C-7
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  • 44
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    Kinematics, influence functions and field quantities for disturbance propagation from moving disturbance sources (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A unified method is presented for deriving the influence functions of moving singularities which determine the field quantities in aerodynamics and aeroacoustics. The moving singularities comprise volume and surface distributions having arbitrary orientations in space and to the trajectory. Hence one generally valid formula for the influence functions which reveal some universal relationships and remarkable properties in the disturbance fields. The derivations used are completely consistent with the physical processes in the propagation field, such that treatment renders new descriptions for some standard concepts. The treatment is uniformly valid for subsonic and supersonic Mach numbers.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77410 , NAS 1.15:77410 , DFVLR-FB-83-01
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  • 45
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    Reduction of the shock wave intensity by modifying the transonic blade trailing edge (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: It is shown that the shock wave intensity can be decreased by using modified trailing edge configurations to reduce or even completely compensate for the effect of the finite thickness of the trailing edge. A theoretical analysis is presented together with numerical results for two supersonic streams flowing off the trailing edge at different velocities. The analysis is based on an ideal gas model.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77029 , NAS 1.15:77029
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  • 46
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    Air intakes for a probative missile of rocket ramjet (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The methods employed to test air intakes for a supersonic guided ramjet powered missile being tested by ONERA are described. Both flight tests and wind tunnel tests were performed on instrumented rockets to verify the designs. Consideration as given to the number of intakes, with the goal of delivering the maximum pressure to the engine. The S2, S4, and S5 wind tunnels were operated at Mach nos. 1.5-3 for the tests, which were compartmentalized into fuselage-intake interaction, optimization of the intake shapes, and the intake performance. Tests were performed on the length and form of the ogive, the presence of grooves, the height of traps in the boundary layer, the types and number of intakes and the lengths and forms of diffusers. Attention was also given to the effects of sideslip, effects of the longitudinal and circumferential positions of the intakes were also examined. Near optimum performance was realized during Mach 2.2 test flights of the prototype rockets.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77407 , NAS 1.15:77407
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  • 47
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    JBFA - buoyant flight (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A method was developed whereby a balloon was used to carry lumber out of a forest in order to continue lumber production without destroying the natural environment and view of the forest. Emphasis was on the best shape for a logging balloon, development of a balloon logging system suitable for cutting lumber and safety plans, tests on balloon construction and development of netting, and weather of mountainous areas, especially solutions to problems caused by winds.
    Keywords: AERODYNAMICS
    Type: NASA-TM-76815 , NAS 1.15:76815
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  • 48
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    Flow mechanism and experimental investigation of a rotating stall in transonic compressors (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The flow characteristics of the rotating stall in compressors is studied, and a flow model is developed along with a theoretical calculation method based on vortex theory. A detailed theoretical calculation is completed for a two dimensional flow field in a transonic rotor in a rotating stall, and the result is in good agreement with experimental findings. The oscillograms of time-varying stall characteristic parameters recorded for the onset, growth, and cessation processes of rotating stall are analyzed, and some new flow phenomena deserving of further investigation are discovered. These include serious separation of individual blades, often preceding the onset of rotating stall in compressors with very small blade-camber angles, and periodical variation of the circumferential width of the stall cell with time, accompanied by periodical oscillation of the width of the stall cell in the radial direction of the blade. The circumferential and radial oscillation frequencies are the same.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77373 , NAS 1.15:77373
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  • 49
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    Wind tunnel investigations of glider fuselages with different waistings and wing arrangements (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The parameters fuselage pinch glider wing arrangement and fuselage leading edge radius of nine glider configurations were investigated in wind tunnel tests. Laminar separation bubbles were found on strongly recessed fuselages. These separations in the juncture between fuselage and wing are essential in the prevention of harmful aerodynamic drag. Drag reduction was measured with increasing pinch and the wing arrangement in the rear. These results are only valid for laminar flow on the fuselage leading edge.
    Keywords: AERODYNAMICS
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  • 50
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    Laminarization of a boundary layer in a supersonic nozzle by cooling of the surface (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The concept of cooling of the surface of wind tunnel walls in order to laminarize the boundary layer, and thereby eliminate perturbations in the working area, is discussed. Equations are given, which are used to calculate the temperature conditions under which the flow in the boundary layer will be stably laminar.
    Keywords: AERODYNAMICS
    Type: NASA-TM-77341 , NAS 1.15:77341
    Format: application/pdf
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