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  • AERODYNAMICS  (415)
  • Cell & Developmental Biology
  • 1975-1979  (648)
  • 1975  (648)
  • 1
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2006-01-11
    Beschreibung: The application of computer techniques for solving Navier-Stokes equations in support of wind tunnel tests is discussed. The ILLIAC IV computer is considered for this purpose and its limitations are analyzed. The author states that improved computers will make it possible to solve many aerodynamic problems and reduce the amount of wind tunnel testing required for adequate data processing.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA/Univ. Conf. on Aeron.; p 211-212
    Format: text
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  • 2
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    In:  CASI
    Publikationsdatum: 2006-01-11
    Beschreibung: Research within NASA relating to the nature of lift-induced vortex wakes behind large aircraft and the means whereby the hazard they represent to smaller aircraft can be alleviated is reviewed. The research, carried out in ground based facilities and in flight shows that more rapid dispersion of the wake can be effected by several means and that the modification of span-loading by appropriate flap deflection holds promise of early practical application.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA/Univ. Conf. on Aeron.; p 143-168
    Format: text
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  • 3
    Publikationsdatum: 2011-10-14
    Beschreibung: A thoroughly documented experiment is reported that was specifically designed to test and guide computations of the interaction of an impinging shock wave with a turbulent boundary layer. Detailed mean flow field and surface data are presented for two shock strengths which resulted in attached and separated flows, respectively. Numerical computations are used to illustrate the dependence of the computations on the particulars of the turbulence models. Models appropriate for zero pressure gradient flows predicted the overall features of the flow fields, but were deficient in predicting many of the details of the interaction regions. Improvements to the turbulence model parameters were sought through a combination of detailed data analysis and computer simulations which tested the sensitivity of the solutions to model parameter changes. Computer simulations using these improvements are presented and discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD Flow Separation; 13 p
    Format: text
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  • 4
    Publikationsdatum: 2011-10-14
    Beschreibung: A method is developed for solving the laminar and turbulent compressible boundary layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent layer, shock wave interactions. Several Navier-Stokes solutions are obtained for each of the laminar boundary layer, shock wave interactions considered. Comparison of these solutions indicates a first order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow. Comparison of the present boundary layer solutions with the Navier-Stokes solutions and with data for a given Mach number indicates that as long as the separation bubble is small, the boundary layer approximation yields solutions whose accuracy is comparable to the Navier-Stokes solutions.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD Flow Separation; 12 p
    Format: text
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  • 5
    Publikationsdatum: 2011-08-16
    Beschreibung: The formulation of mathematical models of aeronautical systems for simulation or other purposes, involves the transformation of aerodynamic stability derivatives. It is shown that these derivatives transform like the components of a second order tensor having one index of covariance and one index of contravariance. Moreover, due to the equivalence of covariant and contravariant transformations in orthogonal Cartesian systems of coordinates, the transformations can be treated as doubly covariant or doubly contravariant, if this simplifies the formulation. It is shown that the tensor properties of these derivatives can be used to facilitate their transformation by symbolic mathematical computation, and the use of digital computers equipped with formula manipulation compilers. When the tensor transformations are mechanised in the manner described, man-hours are saved and the errors to which human operators are prone can be avoided.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aeronautical Quarterly; 26; May 1975
    Format: text
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  • 6
    Publikationsdatum: 2011-08-16
    Beschreibung: A closed-form solution for the sound radiation from multipole sources imbedded in an infinite cylindrical jet with an arbitrary velocity profile is obtained. It is valid in the limit where the wavelength is large compared with the jet radius. Simple formulae for the acoustic pressure field due to convected point sources are also obtained. The results show (in a simple way) how the mean flow affects the radiation pattern from the sources. For convected lateral quadrupoles it causes the exponent of the Doppler factor multiplying the far-field pressure signal to be increased from the value of 3 used by Lighthill to 5.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Fluid Mechanics; 70; Aug. 12
    Format: text
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  • 7
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: The present investigation is an analysis of the radiation from the chemical nonequilibrium region in the shock layer about a vehicle during Venus entry. The radiation and the flow were assumed to be uncoupled. An inviscid, nonequilibrium flowfield was calculated and an effective electronic temperature was determined for the predominant radiating species. Species concentrations and electronic temperature were then input into a radiation transport code to calculate heating rates. The present results confirm earlier investigations which indicate that the radiation should be calculated using electronic temperatures for the radiating species. These temperatures are not related in a simple way to the local translational temperature. For the described mission, the nonequilibrium radiative heating rate is approximately twice the corresponding equilibrium value at peak heating.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Apr. 197
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  • 8
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: A review is presented of progress in attaining technical objectives in three areas of semiautomatic airfoil development: software, hardware, and applications. Software objectives seek improved mathematical models and computer codes for flow analysis and design optimization for a variety of conditions. The 17-step iterative computer model used in designing the GA (W)-1 airfoil is effective but not yet fully automated; with present methods only single-point computer optimization is possible. Hardware objectives calling for improvement in test facilities and techniques are met in part by the introduction of the Langley (F-3C) wind tunnel for independent evaluation of transonic Mach number and Reynolds effects up to 12-16 million, and by a two-dimensional test section for the Langley 1/3 transonic cryogenic tunnel which will extend the Reynolds number to 50 million. The current status of low-speed, thin, and rotorcraft airfoil development programs is discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Astronautics and Aeronautics; 13; Oct. 197
    Format: text
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  • 9
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Apr. 197
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  • 10
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Computational Physics; 17; Feb. 197
    Format: text
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  • 11
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Feb. 197
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  • 12
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets; 12; Jan. 197
    Format: text
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  • 13
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
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  • 14
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 12; Sept
    Format: text
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  • 15
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets; 12; Aug. 197
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  • 16
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Aug. 197
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  • 17
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
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  • 18
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Zeitschrift fuer angewandte Mathematik und Physik; 26; July 25
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  • 19
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 12; Sept
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  • 20
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: The paper sets forth in detail a method for the finite-difference computation of three-dimensional supersonic fields in an Eulerian mesh. First-, second-, and third-order finite difference schemes are examined. Attention is given to proper treatment of the impermeable and permeable boundaries encompassing the computational plane. Numerical results are presented for certain specific configurations: a conical wing-body combination, internal corner flow, a two-dimensional blunt body, an interfering shock problem, and three-dimensional inviscid supersonic flow past a shuttle-orbiter type vehicle.
    Schlagwort(e): AERODYNAMICS
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  • 21
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: Accurate semianalytic solutions to the inverse blunt-body problem have been obtained using a method of series expansion. Rational fractions are employed for series summation and analytic continuation. Angles of incidence up to 30 deg and Mach numbers as low as 2 have been considered. The maximum-entropy streamline will not wet the body surface in asymmetric flow. It may pass either above or below the stagnation streamline. Limit lines appear in the supersonic portion of the flow field, both in the shock layer and in its upstream analytic continuation.
    Schlagwort(e): AERODYNAMICS
    Materialart: Physics of Fluids; 18; Dec. 197
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  • 22
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    In:  Other Sources
    Publikationsdatum: 2011-08-16
    Beschreibung: The paper reviews the experimental data on the incipient separation characteristics of planar delta wings of 75 degree sharp leading edges, with full-span trailing edge flap deflected into the windward flow. The local Reynolds number range for these investigations covered laminar, transitional and turbulent conditions. It is shown that, while turbulent boundary layer data correlates with two dimensional results, in the laminar and transitional cases, there is a nearly parallel shift to higher flap angles for incipient separation.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Oct. 197
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  • 23
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    Publikationsdatum: 2011-08-16
    Beschreibung: A forward-marching procedure for separated boundary-layer flows which permits the rapid and accurate solution of flows of limited extent is presented. The streamwise convection of vorticity in the reversed flow region is neglected, and this approximation is incorporated into a previously developed (Carter, 1974) inverse boundary-layer procedure. The equations are solved by the Crank-Nicolson finite-difference scheme in which column iteration is carried out at each streamwise station. Instabilities encountered in the column iterations are removed by introducing timelike terms in the finite-difference equations. This provides both unconditional diagonal dominance and a column iterative scheme, found to be stable using the von Neumann stability analysis.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Aug. 197
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  • 24
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    In:  CASI
    Publikationsdatum: 2012-05-22
    Beschreibung: Afterbody drag predictions for jet aircraft are usually made experimentally with the jet exhaust flow simulated. The physical gas properties of the fluid used for the model jet exhaust can affect the accuracy of simulation of the airplane's jet exhaust plume. The effect of the accuracy of this simulation on afterbody drag was investigated by wind-tunnel tests with single engine model. In addition to unheated air as the exhaust gas, the decomposition products of three different concentrations of hydrogen peroxide were utilized. The air jet simulation consistently resulted in higher boattail drag than hydrogen peroxide simulation. The differences in drag for the various exhaust gases are attributed to different plume shapes and entrainment properties of the gases. The largest differences in drag due to exhaust gas properties were obtained for the combination of high transonic Mach numbers and high boattail angles. For these conditions, the current data indicate that the use of air to simulate a nonafterburning turbojet exhaust can result in an increase in afterbody amounting to 20 percent of the nonafterburning turbojet value.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD Airframe(Propulsion Interference; 11 p
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  • 25
    Publikationsdatum: 2012-05-22
    Beschreibung: A family of nacelle mounted high angle boattail nozzles was tested to investigate Reynolds number effects on drag. The nozzles were flown on a modified F-106B and mounted on scale models of an F-106 in a wind tunnel. A 19- to 1-range of Reynolds number was covered as a result of the large size differences between models and by flying over a range of altitude. In flight the nozzles were mounted behind J-85 turbojet engines. Jet boundary simulators and a powered turbojet engine simulator were used on the wind tunnel models. Data were taken at Mach numbers of 0.6 and 0.9. Boattail drag was found to be affected by Reynolds number. The effect is a complex relationship dependent upon boundary layer thickness and nozzle boattail shape. As Reynolds number was increased from the lowest values obtained with scale models, boattail drag first increased to a maximum at the lowest flight Reynolds number and then decreased.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD Airframe(Propulsion Interference; 15 p
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  • 26
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A simple aerodynamic bending moment envelope is derived for conventionally shaped airships. This criterion is intended to be used, much like the Naval Architect's standard wave, for preliminary estimates of longitudinal strength requirements. It should be useful in tradeoff studies between speed, fineness ratio, block coefficient, structure weight, and other such general parameters of airship design.
    Schlagwort(e): AERODYNAMICS
    Materialart: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 169-176
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  • 27
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A historical view of multi-jet engine installations is given that emphasizes integration of the powerplant and the airframe in aircraft design for improved reduction in external nacelle drag and interference drag characteristics.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 235-244
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  • 28
    Publikationsdatum: 2016-06-07
    Beschreibung: The analytical prediction and description of transonic flow in turbomachinery is complicated by three fundamental effects: (1) the fluid equations describing the transonic regime are inherently nonlinear, (2) shock waves may be present in the flow, and (3) turbomachine blading is geometrically complex, possessing large amounts of curvature, stagger, and twist. A three-dimensional computation procedure for the study of transonic turbomachine fluid mechanics is described. The fluid differential equations and corresponding difference operators are presented, the boundary conditions for complex blade shapes are described, and the computational implementation and mapping procedures are developed. Illustrative results of a typical unthrottled transonic rotor are also presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 567-585
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  • 29
    Publikationsdatum: 2016-06-07
    Beschreibung: A code developed for simulating high Reynolds number transonic flow fields of arbitrary configuration is described. This code, in conjunction with laboratory experiments, is used to devise and test turbulence transport models which may be suitable in the prediction of such flow fields, with particular emphasis on regions of flow separation. The solutions describe the flow field, including both the shock-induced and trailing-edge separation regions, in sufficient detail to provide the profile and friction drag.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 419-436
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  • 30
    Publikationsdatum: 2016-06-07
    Beschreibung: A method is developed for solving the laminar and turbulent compressible boundary-layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent boundary-layer, shock-wave interactions. Several Navier-Stokes solutions were obtained for each of the laminar boundary-layer, shock-wave interactions considered. Comparison of these solutions indicates a first-order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 151-175
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  • 31
    Publikationsdatum: 2016-06-07
    Beschreibung: The inviscid, internal, and external axial corner flows generated by two intersecting wedges traveling supersonically are obtained by use of a second-order shock-capturing, finite-difference approach. The governing equations are solved iteratively in conical coordinates to yield the complicated wave structure of the internal corner and the simple peripheral shock of the external corner. The numerical results for the internal flows compare favorably with existing experimental data.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 643-658
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  • 32
    Publikationsdatum: 2016-06-07
    Beschreibung: A numerical method for solving the parabolic approximation to the steady-state compressible Navier-Stokes equations is examined. The approximation neglects only the streamwise gradients of shear stress. An implicit finite difference method is used which advances the solution downstream from an initial data surface and determines the complete viscous-inviscid flow between the body and bow shock wave. It is necessary that the inviscid portion of the flow field be supersonic. Crossflow separation is determined as part of the solution. The method is applied to a 15 deg sphere-cone at 15 deg angle of attack, and the results are compared with an inviscid method-of-characteristics calculation.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 531-542
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  • 33
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A previous analysis of fluid filled storage bags is extended to the case of a long fluid filled cylindrical membrane supported by uniform line loads. Cross-sectional shape, stiffness of the support system and stress resultants in the membrane are determined. The application of the numerical results to problems arising in the design of nonrigid airships is discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 199-208
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  • 34
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The forces and moments acting upon a LTA vehicle are considered in order to develop parameters describing planar motion. Similar expressions for HTA vehicles will be given to emphasize the greater complexity of aerodynamic effects when buoyancy effects cannot be neglected. A brief summary is also given of the use of virtual mass coefficients to calculate loads on airships.
    Schlagwort(e): AERODYNAMICS
    Materialart: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 177-186
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  • 35
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: The state-of-the-art on aerodynamic drag reduction is briefly reviewed. The various elements making up the total drag of an aircraft include fuselage, wing, nacelles, trim, interference, tail, and cooling drag.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 11-37
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  • 36
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A number of drag items are related to the performance of a complete aircraft configuration. First, the effect of fuselage camber, wing and nacelle incidence are discussed from a viewpoint of design decision making. Second, the effect of overall cruise drag on the design gross and empty weight of the airplane is discussed. Examples show that cruise drag can have a very important influence on total airplane weight. Third, the effects of usable cruise lift-to-drag ratio and wing loading are shown to be important. Finally several research needs relating to design of the complete configuration are reviewed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 337-351
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  • 37
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Munk's stagger theorem holds that the induced drag of a multiplane is independent of the streamwise position (the stagger) of its lifting elements so long as the gap/span ratios and the element/element lift ratios are specified. In particular, a monoplane-tailplane or a monoplane-foreplane (canard)arrangement can be regarded as a biplane of zero gap and the trim drag due to tailplane download or foreplane upload can be readily calculated. The trim drag penalty is the same for both configurations. Relations are given for trim drag estimates for various practical arrangements.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 319-329
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  • 38
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Optimization of L/D through minimizing induced drag through a detailed flow study together with force, pressure and vorticity measurements is considered. Flow visualization with neutral helium bubbles provides an excellent means of observing the effects of configuration changes.
    Schlagwort(e): AERODYNAMICS
    Materialart: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 215-233
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  • 39
    Publikationsdatum: 2016-06-07
    Beschreibung: Most fuselage geometries cover a portion of the wing leading edge near the plane of symmetry, and it seems reasonable to expect that a large fraction of the leading edge suction which would be developed by the covered wing at high angles of attack is not developed on the fuselage. This is one of the reasons that the Oswald span efficiency factor for the wing body combination fails to approach the value predicted by lifting line theory for the isolated wing. Some traditional and recent literature on wing-body interference is discussed and high Reynolds number data on wing-body-nacelle drag are reviewed. An exposed central leading edge geometry has been developed for a sailplane configuration. Low Reynolds number tests have not validated the design concept.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 107-115
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  • 40
    Publikationsdatum: 2016-06-07
    Beschreibung: Analytical drag methods and wind tunnel evaluation of aircraft design features are used to identify excessive drag of general aviation aircraft with reciprocating engines.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 39-41
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  • 41
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: This summary of drag results presents tabulations on fighter aircraft and light twin general aviation aircraft wind tunnel tests. The figures show that the friction drag for light twins is larger than that for the fighters because of the greater wetted area and the smaller wing area used for reference. Full scale tunnel tests developed the following design features contributing to excessive drag: cooling flow system, engine exhaust stacks, landing gears, control surface gaps, and wing irregularities and leakages.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-60
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  • 42
    Publikationsdatum: 2016-06-07
    Beschreibung: The status of an investigation of four numerical techniques for the time-dependent compressible Navier-Stokes equations is presented. Results for free shear layer calculations in the Reynolds number range from 1000 to 81000 indicate that a sequential alternating-direction implicit (ADI) finite-difference procedure requires longer computing times to reach steady state than a low-storage hopscotch finite-difference procedure. A finite-element method with cubic approximating functions was found to require excessive computer storage and computation times. A fourth method, an alternating-direction cubic spline technique which is still being tested, is also described.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 437-468
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  • 43
    Publikationsdatum: 2016-06-07
    Beschreibung: A review is given of recent advances in two distinct computational methods for evaluating turbulence fields, namely, statistical Reynolds stress modeling and turbulence simulation, where large eddies are followed in time. It is shown that evaluation of the mean Reynolds stresses, rather than use of a scalar eddy viscosity, permits an explanation of streamline curvature effects found in several experiments. Turbulence simulation, with a new volume averaging technique and third-order accurate finite-difference computing is shown to predict the decay of isotropic turbulence in incompressible flow with rather modest computer storage requirements, even at Reynolds numbers of aerodynamic interest.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 317-339
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  • 44
    Publikationsdatum: 2016-06-07
    Beschreibung: Numerical solutions are presented for the laminar and turbulent boundary-layer equations for incompressible flows with separation and reattachment. The separation angularity is avoided by using an inverse technique in which the displacement thickness is prescribed and the pressure is deduced from the resulting solution. The turbulent results appear qualitatively correct despite the use of a two-layer eddy-viscosity model which is generally assumed appropriate only for mild-pressure-gradient flows. A new viscous-inviscid interaction technique is presented in which the inviscid flow is solved inversely by prescribing the pressure from the boundary-layer solution and deducing the new displacement thickness from the solution of a Cauchy integral. Calculations are presented using this interaction procedure for a laminar flow in which separation and reattachment occur on a solid surface.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 125-150
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  • 45
    Publikationsdatum: 2016-06-07
    Beschreibung: Shock-capturing solutions for an axisymmetric supersonic inlet at small angles of attack are obtained. Good overall agreement between the shock-capturing solutions and experimental data is shown except in regions of strong viscous effects or boundary-layer removal. Although the results indicate a strong potential for the use of shock-capturing or finite-difference solutions for internal flows, improvement in the ability to handle the reflection of strong shockwaves having downstream Mach numbers near 1 is needed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 623-642
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  • 46
    Publikationsdatum: 2016-06-07
    Beschreibung: A very general method for calculating compressible three-dimensional laminar and turbulent boundary layers on arbitrary wings is described. The method utilizes a nonorthogonal coordinate system for the boundary-layer calculations and includes a geometry package that represents the wing analytically. In the calculations all the geometric parameters of the coordinate system are accounted for. The Reynolds shear-stress terms are modeled by an eddy-viscosity formulation developed by Cebeci. The governing equations are solved by a very efficient two-point finite-difference method used earlier by Keller and Cebeci for two-dimensional flows and later by Cebeci for three-dimensional flows.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 41-76
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  • 47
    Publikationsdatum: 2016-06-07
    Beschreibung: A numerical method is presented which is valid for integration of the parabolic-elliptic Navier-Stokes equations. The solution procedure is applied to the three-dimensional supersonic flow of a jet issuing into a supersonic free stream. Difficulties associated with the imposition of free-stream boundary conditions are noted, and a coordinate transformation, which maps the point at infinity onto a finite value, is introduced to alleviate these difficulties. Results are presented for calculations of a square jet and varying-aspect-ratio rectangular jets. The solution behavior varies from axisymmetry for the square jet to nearly two-dimensional for the high-aspect-ratio rectangle, although the computation always calculates the flow as though it were truly three-dimensional.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 543-565
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  • 48
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Numerical solutions of the complete, time-averaged conservation equations using several eddy-viscosity models for the Reynolds shear stress to close the equations are compared with experimental measurements in a compressible, turbulent separated flow. An efficient time-splitting, explicit difference scheme was used to solve the two-dimensional conservation equations. The experiment used for comparison was a turbulent boundary layer that was separated by an incident shock wave in a Mach 2.93 flow with a unit Reynolds number of 5.7 x 10 to the seventh power m. Comparisons of predicted and experimental values of surface pressure, shear stress along the wall, and velocity profiles are shown. One of the tested eddy-viscosity models which allows the shear stress to be out of equilibrium with the mean flow produces substantially better agreement with the experimental measurements than the simpler models. A tool is thereby provided for inferring additional information about the flow, such as static pressures in the stream, which might not be directly obtainable from experiments.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 401-417
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  • 49
    Publikationsdatum: 2016-06-07
    Beschreibung: It is shown that disturbances in external flow can significantly affect, by as much as an order of magnitude, the turbulent mixing rate in free shear layers and that the length scale of the external flow disturbances is as important as the amplitude. The difference between the effect of wide-band and narrow-band disturbances is stressed. The model for pressure fluctuation term in the kinetic energy equation is included in a two-equation model. The reduced spreading rate in high Mach number, high Reynolds number, adiabatic, free turbulent shear layers is predicted.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 341-376
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  • 50
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Tail size requirement calculations are presented for a vertical tail performing a coordinated turn reversal at corresponding load requirements with minimum tail drag.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-446
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  • 51
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: A discussion of data of and methods for predicting trim drag is presented. Specifically the following subjects are discussed: (1) economic impact of trim drag; (2) the trim drag problem in propeller driven airplanes and the effect of propeller and nacelle location; (3) theoretical procedures for predicting trim drag; and (4) research needs in the area of trim drag.
    Schlagwort(e): AERODYNAMICS
    Materialart: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 295-305
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  • 52
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    In:  CASI
    Publikationsdatum: 2016-06-07
    Beschreibung: Modifications are proposed to standard estimating procedures, as well as the BODY computer program, which predict that the drag of two nacelles will equal the drag of the fuselage. A preliminary computer analysis that considers increased dimensions for the nacelle forebody so that the noise is relatively less blunt indicates a reduction in form drag much greater than the increase in skin friction drag attributable to increased surface area.
    Schlagwort(e): AERODYNAMICS
    Materialart: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 257-261
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  • 53
    Publikationsdatum: 2016-06-07
    Beschreibung: Three-dimensional unsteady transonic flow through an axial turbomachine stage is described in terms of a pair of two-dimensional formulations pertaining to orthogonal surfaces, namely, a blade-to-blade surface and a hub-to-casing surface. The resulting systems of nonlinear, inviscid, compressible equations of motion are solved by an explicit finite-difference technique. The blade-to-blade program includes the periodic interaction between rotor and stator blade rows. Treatment of the boundary conditions and of the blade slipstream motion by a characteristic type procedure is discussed in detail. Harmonic analysis of the acoustic far field produced by the blade row interaction, including an arbitrary initial transient, is outlined. Results from the blade-to-blade program are compared with experimental measurements of the rotating pressure field at the tip of a high-speed fan. The hub-to-casing program determines circumferentially averaged flow properties on a meridional plane. Blade row interactions are neglected in this formulation, but the force distributions over the entire blade surface for both the rotor and stator are obtained. Results from the hub-to-casing program are compared with a relaxation method solution for a subsonic rotor. Results are also presented for a quiet fan stage which includes transonic flow in both the rotor and stator and a normal shock in the stator.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 587-621
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  • 54
    Publikationsdatum: 2016-06-07
    Beschreibung: A three-dimensional boundary-layer code was developed for particular application to realistic hypersonic aircraft. It is very general and can be applied to a wide variety of boundary-layer flows. Laminar, transitional, and fully turbulent flows of compressible, reacting gases are efficiently calculated by use of the code. A body-oriented orthogonal coordinate system is used for the calculation and the user has complete freedom in specifying the coordinate system within the restrictions that one coordinate must be normal to the surface and the three coordinates must be mutually orthogonal.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 77-99
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  • 55
    Publikationsdatum: 2016-06-07
    Beschreibung: An implicit finite-difference procedure is presented for solving the compressible three-dimensional boundary-layer equations. The method is second-order accurate, unconditionally stable (conditional stability for reverse cross flow), and efficient from the viewpoint of computer storage and processing time. The Reynolds stress terms are modeled by (1) a single-layer mixing length model and (2) a two-layer eddy viscosity model. These models, although simple in concept, accurately predicted the equilibrium turbulent flow for the conditions considered. Numerical results are compared with experimental wall and profile data for a cone at an angle of attack larger than the cone semiapex angle. These comparisons clearly indicate that the numerical procedure and turbulence models accurately predict the experimental data with as few as 21 nodal points in the plane normal to the wall boundary.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 17-40
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  • 56
    Publikationsdatum: 2019-06-28
    Beschreibung: A numerical method was developed for calculating axisymmetric transonic (M greater than 1) flow about a blunt body; the bow shock wave location was investigated. A Rankine-Hugoniot jump was applied at the shock while relaxation on the isentropic equation of motion was used between shock and body. The shock wave is adjusted by a Newton type iteration scheme. Results are given for a sphere in the Mach number range 1.62 down to 1.02.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-72448 , NRC-14765 , LR-586 , (ISSN 0077-5541)
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  • 57
    Publikationsdatum: 2019-06-27
    Beschreibung: Models of three practical oblique-wing transport configurations were tested in the NASA Ames 11 foot wind tunnel. The three configurations used a common forward fuselage, wing, and support system but employed different aft fuselage sections simulating alternate propulsion system installations. These included an integrated propulsion system, pylon-mounted nacelles, and clean (no propulsion system) configuration. The tests were conducted over a Mach number range from 0.6 to 1.4 and at sweep angles from 0 to 60 degrees. The nominal unit Reynolds number was 1.83 million per meter and the angle of attack range was -3 to +6 degrees. The models were mounted in the tunnel by means of a lower blade support system. The interference effects of this lower blade and the flow inclination were determined by using an image blade system and testing the configuration in both the upright and inverted positions.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-137697 , HST-TR-344-0
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  • 58
    Publikationsdatum: 2019-06-28
    Beschreibung: Refinements in a 10 percent thick supercritical airfoil (airfoil 31) have produced significant improvements in the drag characteristics compared with those for an earlier supercritical airfoil (airfoil 12) designed for the same normal force coefficient of 0.7. Drag creep was practically eliminated at normal force coefficients between about 0.4 and 0.7 and was greatly reduced at other normal force coefficients. Substantial reductions in the drag levels preceding drag divergence were also achieved at all normal force coefficients. The Mach numbers at which drag diverges were delayed for airfoil 31 at normal force coefficients up to about 0.6 (by approximately 0.01 and 0.02 at normal force coefficients of 0.4 and 0.6, respectively) but drag divergence occurred at slightly lower Mach numbers at higher normal force coefficients.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3203 , L-9841 , NAS 1.15:X-3203
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  • 59
    Publikationsdatum: 2019-06-28
    Beschreibung: The static longitudinal stability characteristics of a 0.09 scale model of an airplane with a modified 17 percent thick supercritical wing were investigated. Modifications were made to the wing to reduce a gradual buildup of boundary layer shock loss preceding drag divergence (drag creep) noted in an earlier investigation. The longitudinal aerodynamic characteristics were determined over a Mach number range from 0.30 to 0.76 at angles of attack that generally provided a lift coefficient range from 0 to buffet onset. Results indicate that the modifications to the airfoil essentially eliminated the drag creep associated with the airfoil that occurs between the critical Mach number and the drag divergence Mach number.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3211 , L-9960 , NAS 1.15:X-3211
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  • 60
    Publikationsdatum: 2019-06-28
    Beschreibung: A 1/9 scale model of an existing executive type jet transport refitted with a supercritical wing was tested on in the 8 foot transonic pressure tunnel. The supercritical wing had the same sweep as the original airplane wing but had maximum thickness chord ratios 33 percent larger at the mean geometric chord and almost 50 percent larger at the wing-fuselage juncture. Wing pressure distributions and fuselage pressure distributions in the vicinity of the left nacelle were measured at Mach numbers from 0.25 to 0.90 at angles of attack that generally varied from -2 deg to 10 deg. Results are presented in tabular form without analysis.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-72701 , NAS 1.15:X-72701
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  • 61
    Publikationsdatum: 2019-06-28
    Beschreibung: An investigation was conducted in the Langley Research Center 8-foot transonic pressure tunnel to determine the effects of the landing gear, speed brake and the major airplane protuberances on the longitudinal aerodynamic characteristics of an 0.087-scale model of the TF-8A supercritical-wing research airplane. For the effects of the landing gear and speed brake, tests were conducted at Mach numbers of 0.25 and 0.35 with a flap deflection of 20 degrees and a horizontal-tail angle of -10 degrees. These conditions simulated those required for take-off and landing. The effects of the protuberances were determined with the model configured for cruise (i.e., horizontal-tail angle of -2.5 degrees and no other control deflection), and these tests were conducted at Mach numbers from 0.50 to 1.00. The angle-of-attack range for all tests varied from about -5 degrees to 12 degrees.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-72684 , NAS 1.15:X-72684
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  • 62
    Publikationsdatum: 2019-06-27
    Beschreibung: A momentum theory was developed for rotors in descending flight. Comparison with available experimental data indicates that the theory, when properly interpreted, yields the optimum performance of the rotor. Power settling can be explained on the basis of the theory. The reasons and the need for operational restrictions on descending flight are discussed. The maximum autorotative performance of a rotor is determined; the theory shows good agreement with flight measurements in autorotation. Similar equations were developed for a wing; it was shown that the ideal performance of an autorotating rotor is identical to that of a wing of equal aspect ratio. A limiting maximum wing lift coefficient which is confirmed by existing experimental data was obtained.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TN-D-7917 , L-10045
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  • 63
    Publikationsdatum: 2019-06-27
    Beschreibung: For abstract, see N75-32026.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-132710 , D6-41789-PT-2
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  • 64
    Publikationsdatum: 2019-06-27
    Beschreibung: Large-scale aircraft lavatory and cargo compartment fire tests are described. Tests were conducted to evaluate the effectiveness of these compartments to contain fire and smoke. Two tests were conducted and are detailed. Test 1 involved a production Boeing 747 lavatory of the latest design installed in an enclosure outside the aircraft, to collect gases and expose animals to these gases. Results indicate that the interior of the lavatory was completely burned, evolving smoke and combustion products in the enclosure. Test 2 involved a simulated Douglas DC-10 cargo compartment retro-fitted with standard fiberglass liner. The fire caused excessive damage to the liner and burned through the ceiling in two areas. Test objectives, methods, materials, and results are presented and discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-62471 , A-6235
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  • 65
    Publikationsdatum: 2019-06-27
    Beschreibung: A method of predicting forces, moments, and detailed surface pressures on thin, sharp-edged wings with leading-edge vortex separation in incompressible flow is presented. The method employs an inviscid flow model in which the wing and the rolled-up vortex sheets are represented by piecewise, continuous quadratic doublet sheet distributions. The Kutta condition is imposed on all wing edges. Computed results are compared with experimental data and with the predictions of the leading-edge suction analogy for a selected number of wing planforms over a wide range of angle of attack. These comparisons show the method to be very promising, capable of producing not only force predictions, but also accurate predictions of detailed surface pressure distributions, loads, and moments.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-132709 , D6-41789-PT-1
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  • 66
    Publikationsdatum: 2019-06-27
    Beschreibung: An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary layer after a shock wave-boundary layer interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2595 , FTAS/TR-75-100
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  • 67
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    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: An analysis of stall-induced helicopter rotor blade torsional oscillations was carried out, the primary objectives being to predict the onset and severity of the oscillations and their relationship to aircraft and blade parameters. Blade flapping, flapwise bending, and torsional degrees of freedom were taken into account, with radial variation in aerodynamic loading determined from a previously developed dynamic stall model. Results of analyses were compared with data from flight tests of helicopters. Analyses were carried out while parametrically varying blade vibrational characteristics. It was found that the amplitudes of the higher harmonics of torsional oscillations can be significantly reduced by either reducing the torsional natural frequency or introducing viscous damping in the torsional degree of freedom. A preliminary investigation was conducted to determine the feasibility and practicality of alleviating the stall problem by means of boundary layer control. The results indicate that boundary layer control would be effective in reducing the higher harmonics of torsional oscillations due to stall and that its implementation would not require excessive power or suction rates.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2573
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  • 68
    Publikationsdatum: 2019-06-27
    Beschreibung: Strain-gage bridges were used to make in-flight measurements of bending moment, shear, and torque loads on a low-aspect-ratio, thin, swept wing having a full depth honeycomb sandwich type structure. Standard regression analysis techniques were employed in the calibration of the strain bridges. Comparison of the measured loads with theoretical loads are included.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TN-D-7979 , L-9896
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  • 69
    Publikationsdatum: 2019-06-27
    Beschreibung: Investigations were conducted in the Ames 40- by 80-Foot Wind Tunnel to determine the aerodynamic characteristics of a large-scale subsonic jet transport model with an upper surface blown flap system. The model had a 25 deg swept wing of aspect ratio 7.28 and four turbofan engines. The lift of the flap system was augmented by turning the turbofan exhaust over the Coanda surface. Results were obtained for several flap deflections with several wing leading-edge configurations at jet momentum coefficients from 0 to 4.0. Three-component longitudinal data are presented with four engines operating. In addition, longitudinal and lateral data are presented with an engine out. The maximum lift and stall angle of the four engine model were lower than those obtained with a two engine model that was previously investigated. The addition of the outboard nacelles had an adverse effect on these values. Efforts to improve these values were successful. A maximum lift of 8.8 at an angle-of-attack of 27 deg was obtained with a jet thrust coefficient of 2 for the landing flap configuration.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-62419 , A-6003
    Format: application/pdf
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  • 70
    Publikationsdatum: 2019-06-27
    Beschreibung: A flow model has been developed to study the flow development after reattachment with supersonic external streams. Special attention is given to the pressure difference across the viscous layer, and it is suggested that such a flow redevelopment can be treated as a relaxation of this pressure difference. Upon correlating the pressure difference with a slope parameter of the velocity profile, the system of equations governing the flow would produce a saddle point singularity corresponding to the fully rehabilitated asymptotic flow condition. A method of calculation for this flowfield, in conjunction with the matching of the upstream flow, has been derived and is discussed. Samples of calculations are also presented. Reasonably good agreement with experimental data has also been observed.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Dec. 197
    Format: text
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  • 71
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    In:  Other Sources
    Publikationsdatum: 2019-06-27
    Beschreibung: A lifting surface theory based on a parallel shear flow model is presented for steady, incompressible flows. The theory is intended to account approximately for the presence of a boundary layer. The method of Fourier transforms is used to calculate the pressure on a surface of infinite extent and arbitrary contour. Immediately above the surface is a region of sheared flow (the boundary layer), outside of which the flow velocity is constant. The Fourier transform of the pressure on this surface is used to derive the shear flow equivalent to the kernel function of classical potential flow lifting surface theory. The kernel function provides an integral relation between the upwash at a given point on the surface and the pressure everywhere on the surface. This relation is treated as an integral equation for the pressure, and is solved numerically. Computations are presented for the lift and pitching moment on a flat plate in two-dimensional flow, and for flat, rectangular wings of aspect ratio 1, 2, and 5. As expected, the shear layer decreases the lift curve slope; however, the shear layer (whose thickness is constant along the wing chord) has little effect on the center of pressure.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Sept
    Format: text
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  • 72
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-06-27
    Beschreibung: A method is developed to determine the flowfield of a body of revolution in separated flow. The technique employed is the use of the computer to integrate various solutions and solution properties of the sub-flowfields which make up the entire flowfield without resorting to a finite difference solution to the complete Navier-Stokes equations. The technique entails the use of the unsteady cross flow analogy and a new solution to the required two-dimensional unsteady separated flow problem based upon an unsteady discrete-vorticity wake. Data for the forces and moments on bodies of revolution at high angle of attack (outside the range of linear inviscid theories) such that the flow is substantially separated are produced which compare well with experimental data at low speeds. In addition, three-dimensional steady separation regions and wake vortex patterns are determined.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft; 12; Feb. 197
    Format: text
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  • 73
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: Sonic boom pressure signatures were measured in supersonic and hypersonic wind tunnels for models of the space shuttle launch vehicle at 0 deg angle of attack with and without solid body simulations of the exhaust plumes. Data were measured at 30 deg increments in roll angle from 90 deg to 180 deg at Mach numbers from 3.02 to 5.56.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-62441 , A-6092
    Format: application/pdf
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  • 74
    Publikationsdatum: 2019-06-27
    Beschreibung: A study was made of the upwash interference caused by the wind tunnel walls at a Mach number of 0.20. The wind tunnel has slotted horizontal walls and solid vertical walls and the wind tunnel model is a wing-fuselage combination typical of a short take-off and landing (STOL) transport. Measurements were made of the model forces and angle of attack. The experimental results are compared to theoretical solutions for the upwash interference. This comparison enabled an indirect determination of one of the constants in the slotted wall boundary condition. The magnitude of the experimental upwash interference is also compared to the accuracy of the data. This comparison indicates that it is difficult to make definite conclusions based on the experimental data. Suggestions are made for future research which could provide a practical means of accurately determining the wall-interference velocities in wind tunnels with rigid slotted walls.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3218 , L-10042
    Format: application/pdf
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  • 75
    Publikationsdatum: 2019-06-27
    Beschreibung: The construction of a theoretical flow field due to shedding of vortex rings, the identification of the controlling parameters, and the determination of whether the theoretical model successfully simulated the unsteady pressure field near jet (and consequently the far field noise) was studied. The basic parameters contained in the analytic solutions were the epoch at which a vortex ring was shed near the jet exit and the eddy viscosity coefficient. These parameters were identified from the experimental data for the real-time pressure and from the spread of the mixing layer of the jet. Results of the theoretical analysis show good qualitative agreement with the experimental data.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-143211 , TR-75-T10
    Format: application/pdf
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  • 76
    Publikationsdatum: 2019-06-27
    Beschreibung: The analytical techniques and computer program developed in the fully-coupled rotor vibration study are described. The rotor blade natural frequency and mode shape analysis was implemented in a digital computer program designated DF1758. The program computes collective, cyclic, and scissor modes for a single blade within a specified range of frequency for specified values of rotor RPM and collective angle. The analysis includes effects of blade twist, cg offset from reference axis, and shear center offset from reference axis. Coupled inplane, out-of-plane, and torsional vibrations are considered. Normalized displacements, shear forces and moments may be printed out and Calcomp plots of natural frequencies as a function of rotor RPM may be produced.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-132662 , REPT-299-099-724
    Format: application/pdf
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  • 77
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: The finite element procedure is shown to be of significant impact in design of the 'computational wind tunnel' for low speed aerodynamics. The uniformity of the mathematical differential equation description, for viscous and/or inviscid, multi-dimensional subsonic flows about practical aerodynamic system configurations, is utilized to establish the general form of the finite element algorithm. Numerical results for inviscid flow analysis, as well as viscous boundary layer, parabolic, and full Navier Stokes flow descriptions verify the capabilities and overall versatility of the fundamental algorithm for aerodynamics. The proven mathematical basis, coupled with the distinct user-orientation features of the computer program embodiment, indicate near-term evolution of a highly useful analytical design tool to support computational configuration studies in low speed aerodynamics.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-143190 , TR-75-T5
    Format: application/pdf
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  • 78
    Publikationsdatum: 2019-06-27
    Beschreibung: A two-dimensional inlet was alternately mated to a coldpipe plug assembly and a J85-GE-13 turbojet engine, and placed in a Mach 0.4 stream so as to ingest the tip vortex of a forward mounted wing. Vortex properties were measured just forward of the inlet and at the compressor face. Results show that ingestion of a wing tip vortex by a turbojet engine can cause a large reduction in engine stall margin. The loss in stall compressor pressure ratio was primarily dependent on vortex location and rotational direction and not on total-pressure distortion.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3246 , E-8213
    Format: application/pdf
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  • 79
    Publikationsdatum: 2019-06-27
    Beschreibung: An integrated system of computer programs for supersonic configurations is described. An explanation of system usage, the input definitions, and example output are included. For Part 1, see N75-18185; for Part 3, see N75-18186.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2521 , D6-41759-PT-2
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  • 80
    Publikationsdatum: 2019-06-27
    Beschreibung: Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-56032
    Format: application/pdf
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  • 81
    Publikationsdatum: 2019-06-27
    Beschreibung: Various control-volume models used to analyze the shock boundary layer bleed interaction were investigated. The bleed assumptions of the models and their influence on the analytical solutions are discussed. The results of the analysis using these models are compared with experimental boundary-layer data taken in a supersonic inlet. The experimental Mach number upstream of the interaction was 1.66, and the oblique-shock pressure ratio was 1.33. The boundary layer data included bleed flow rates up to approximately 0.6 of the upstream boundary layer mass flow rate. The first model assumed the bleed was removed from the control volume with a momentum that was characterized by a pressure intermediate between the upstream and downstream pressures. The second model assumed the control volume was bounded by a streamline dividing the bleed and residual flows and eliminated the need to specify the momentum of the bleed flow. Comparison of the results using the models showed that specifying the bleed pressure in one model was equivalent to specifying the pressure along the dividing streamline in the other.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3186 , E-7866
    Format: application/pdf
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  • 82
    facet.materialart.
    Unbekannt
    In:  Other Sources
    Publikationsdatum: 2019-06-27
    Beschreibung: An analytical approximation is obtained to the solution of the equation describing the combined effects of bluntness and boundary-layer displacement on the hypersonic flow over a wedge for the case where the constant parameter in the governing equation, which is proportional to the angle of attack, is greater than zero. It is shown that the approximation has good physical accuracy over the entire range of conditions to which the theory is applicable for positive angle of attack.
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal; 13; Sept
    Format: text
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  • 83
    Publikationsdatum: 2019-06-27
    Beschreibung: Simple stability methods are used to derive an approximate, closed-form expression for the lead-lag damping of rotor blades in hover. Destabilizing terms are shown to be a result of two dynamic mechanisms. First, the destabilizing aerodynamic forces that can occur when blade lift is higher than a critical value are maximized when the blade motion is in a straight line equidistant from the blade chord and the average direction of the air flow velocity. This condition occurs when the Coriolis terms vanish and when the elastic coupling terms align the blade motion with this least stable direction. Second, the nonconservative stiffness terms that result from pitch-flap or pitch-lag coupling can add or subtract energy from the system depending upon whether the motion of the blade tip is clockwise or counterclockwise.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-62425 , A-6025
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  • 84
    Publikationsdatum: 2019-06-27
    Beschreibung: Application of a general method for calculation of inviscid hypersonic flow fields is discussed. General considerations are analyzed along with the sonic corner and the stagnation region. It is concluded that the complications caused by the requirement for sonic flow at the rear corner and particularly by the uncertain position of the stagnation streamline lead to sufficient difficulties with convergence of iterations that a practical procedure is not likely to be found.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-132652 , MML-TR-75-10C
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  • 85
    Publikationsdatum: 2019-06-27
    Beschreibung: A hemispherical head flow direction sensor was tested in a wind tunnel to evaluate its effectiveness for measuring dynamic duct flow direction angles of plus and minus 27 degrees. The tests were conducted at Reynolds numbers of 3.8 million per meter (1.0 million per foot) and 4.92 million per meter (1.5 million per foot) and at Mach numbers from 0.30 to 0.70. The design criteria for the probe are discussed and the wind tunnel results are presented. Three techniques for deriving the flow angles are described.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3232 , H-862
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  • 86
    Publikationsdatum: 2019-06-27
    Beschreibung: Wind-Tunnel tests were conducted in the Lockheed-Georgia Company's compressible flow facility to determine the transonic two-dimensional aerodynamic characteristics of a NACA 65 sub 1-213 a = 0.50 airfoil. The results are correlated with data obtained in the NASA-Langley 8-foot transonic pressure tunnel and the NAE high Reynolds number 15x60-inch two-dimensional test facility. The tests were conducted over a Mach number range from 0.60 to 0.80 and an angle of attack range from -1 deg to 8 deg. Reynolds numbers, based on the airfoil chord, were varied.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2499
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  • 87
    Publikationsdatum: 2019-06-27
    Beschreibung: The Langley 1/8-scale V/STOL model tunnel was used to qualitatively determine the flow fields associated with semi-span close coupled canard wing and strake wing models. Small helium filled bubbles were injected upstream of the models to make the flow visible. Photographs were taken over the angle-of-attack ranges of -10 deg to 40 deg.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-72668
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  • 88
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: Lift generated pressures produced by large, heavy aircraft at low altitudes were investigated due to concern over their possible effects on ground objects. Aircraft lift generated pressures were calculated using elementary airfoil theory, and these values were compared with ground level measurements made during an overflight program. The predicted and the measured values were in relatively good agreement. Due to lack of experimental investigations of this phenomenon, opportunity was taken during an overflight program to use a specially instrumented test range to measure the ground pressures produced for a range of aircraft weights and distances.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-72707
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  • 89
    Publikationsdatum: 2019-06-27
    Beschreibung: A viscid-inviscid interaction procedure for the calculation of subsonic and transonic flow over a boattail was developed. This method couples a finite-difference inviscid analysis with an integral boundary-layer technique. Results indicate that the effect of the boundary layer is as important as an accurate inviscid method for this type of flow. Theoretical results from the solution of the full transonic-potential equation, including boundary layer effects, agree well with the experimental pressure distribution for a boattail. Use of the small disturbance transonic potential equation yielded results that did not agree well with the experimental results even when boundary-layer effects were included in the calculations.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TN-D-7984 , E-8065
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  • 90
    facet.materialart.
    Unbekannt
    In:  CASI
    Publikationsdatum: 2019-06-27
    Beschreibung: An analytical solution was obtained for the perturbation velocity potential for transonic flow about lifting wing-body configurations with order-one span-length ratios and small reduced-span-length ratios and equivalent-thickness-length ratios. The analysis is performed with the method of matched asymptotic expansions. The angles of attack which are considered are small but are large enough to insure that the effects of lift in the region far from the configuration are either dominant or comparable with the effects of thickness. The modification to the equivalence rule which accounts for these lift effects is determined. An analysis of transonic flow about lifting wings with large aspect ratios is also presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TR-R-440 , L-9969
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  • 91
    Publikationsdatum: 2019-06-27
    Beschreibung: Tests were made on a 0.762-meter-tip-diameter research turbine to determine the effect of blade coolant flow on its aerodynamic performance. Both stator and rotor blades had trailing-edge slots for coolant ejection. The turbine was tested over a range of speed and pressure ratio. High primary efficiencies, calculated on the basis of primary air only, were obtained. The efficiency attained was identical to that reported for the turbine from a previous investigation were only slotted stator blades where incorporated in the turbine and tested. And it also compares with results for the turbine with solid blading. Independently varying the rotor coolant flow showed that rotor cooling imposed a severe penalty on turbine efficiency. The thermodynamic efficiency, which accounts for the ideal energies of both blade coolant flows, decreased linearly with rotor coolant at a rate of about 0.7 percent per percent rotor coolant fraction.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3214 , E8158
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  • 92
    Publikationsdatum: 2019-06-27
    Beschreibung: The historical development of analytical methods for predicting the lift, drag, and pitching moment of complete light aircraft configurations in cruising flight is reviewed. Theoretical methods, based in part on techniques described in the literature and in part on original work, are developed. These methods form the basis for understanding the computer programs given to: (1) compute the lift, drag, and moment of conventional airfoils, (2) extend these two-dimensional characteristics to three dimensions for moderate-to-high aspect ratio unswept wings, (3) plot complete configurations, (4) convert the fuselage geometric data to the correct input format, (5) compute the fuselage lift and drag, (6) compute the lift and moment of symmetrical airfoils to M = 1.0 by a simplified semi-empirical procedure, and (7) compute, in closed form, the pressure distribution over a prolate spheroid at alpha = 0. Comparisons of the predictions with experiment indicate excellent lift and drag agreement for conventional airfoils and wings. Limited comparisons of body-alone drag characteristics yield reasonable agreement. Also included are discussions for interference effects and techniques for summing the results above to obtain predictions for complete configurations.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2523
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  • 93
    Publikationsdatum: 2019-06-27
    Beschreibung: An investigation was conducted on a CDC 7600 digital computer to determine the effects of additional thickness distributions to the upper surface of the NACA 64-206 and 64 sub 1 - 212 airfoils. The additional thickness distribution had the form of a continuous mathematical function which disappears at both the leading edge and the trailing edge. The function behaves as a polynomial of order epsilon sub 1 at the leading edge, and a polynomial of order epsilon sub 2 at the trailing edge. Epsilon sub 2 is a constant and epsilon sub 1 is varied over a range of practical interest. The magnitude of the additional thickness, y, is a second input parameter, and the effect of varying epsilon sub 1 and y on the aerodynamic performance of the airfoil was investigated. Results were obtained at a Mach number of 0.2 with an angle-of-attack of 6 degrees on the basic airfoils, and all calculations employ the full potential flow equations for two dimensional flow. The relaxation method of Jameson was employed for solution of the potential flow equations.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-137703 , TN-199
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  • 94
    Publikationsdatum: 2019-06-27
    Beschreibung: An investigation was conducted on a CDC 7600 digital computer to determine the effects of additional thickness distributions to the upper surface of an NACA 64-206 airfoil. Additional thickness distributions employed were in the form of two second-order polynomial arcs which have a specified thickness at a given chordwise location. The forward arc disappears at the airfoil leading edge, the aft arc disappears at the airfoil trailing edge. At the juncture of the two arcs, x = x, continuity of slope is maintained. The effect of varying the maximum additional thickness and its chordwise location on airfoil lift coefficient, pitching moment, and pressure distribution was investigated. Results were obtained at a Mach number of 0.2 with an angle-of-attack of 6 degrees on the basic NACA 64-206 airfoil, and all calculations employ the full potential flow equations for two dimensional flow. The relaxation method of Jameson was employed for solution of the potential flow equations.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-137702 , TN-195
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  • 95
    Publikationsdatum: 2019-06-27
    Beschreibung: The probable descent operating conditions for a hypersonic air-breathing research airplane were examined. Descents selected were cruise angle of attack, high dynamic pressure, high lift coefficient, turns, and descents with drag brakes. The descents were parametrically exercised and compared from the standpoint of cold-wall (367 K) aircraft heat load. The descent parameters compared were total heat load, peak heating rate, time to landing, time to end of heat pulse, and range. Trends in total heat load as a function of cruise Mach number, cruise dynamic pressure, angle-of-attack limitation, pull-up g-load, heading angle, and drag-brake size are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TN-D-7860 , L-9778
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  • 96
    Publikationsdatum: 2019-06-27
    Beschreibung: A digital computer program has been developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge or trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges have been extracted analytically as a preliminary step to solving the integral equation by collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accommodated.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-132634
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  • 97
    Publikationsdatum: 2019-06-27
    Beschreibung: An investigation was conducted on a CDC 7600 digital computer to determine the effects of additional thickness distributions to the upper surface of an NACA 64 sub 1 - 212 airfoil. Additional thickness distributions employed were in the form of two second-order polynomial arcs which have a specified thickness at a given chordwise location. The forward arc disappears at the airfoil leading edge, the aft arc disappears at the airfoil trailing edge. At the juncture of the two arcs, x = x, continuity of slope is maintained. The effect of varying the maximum additional thickness and its chordwise location on airfoil lift coefficient, pitching moment, and pressure distribution was investigated. Results were obtained at a Mach number of 0.2 with an angle-of-attack of 6 degrees on the basic NACA 64 sub 1 - 212 airfoil, and all calculations employ the full potential flow equations for two dimensional flow. The relaxation method of Jameson was employed for solution of the potential flow equations.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-137701 , TN-194
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  • 98
    Publikationsdatum: 2019-06-27
    Beschreibung: A theoretical analysis is developed for a coupled helicopter rotor system to allow determination of the loads and dynamic response behavior of helicopter rotor systems in both steady-state forward flight and maneuvers. The effects of an anisotropically supported swashplate or gyroscope control system and a deformed free wake on the rotor system dynamic response behavior are included.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-2453
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  • 99
    Publikationsdatum: 2019-06-27
    Beschreibung: The aerodynamic performance of a core turbine vane with a ceramic coating was investigated experimentally in a two-dimensional cascade of 10 vanes. The vane was first tested with a rough coating and then retested after the coating had been smoothed. The test fluid was atmospheric air. The cascade tests covered a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95. The principal measurements were cross-channel surveys of exit total pressure, static pressure, and flow angle. The results presented include exit survey results and overall performance in terms of flow angle, weight flow, and kinetic energy loss. The performance of the ceramic-coated vanes is compared with the performance of an uncoated vane having a similar profile.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-TM-X-3191 , E-8137
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  • 100
    Publikationsdatum: 2019-06-27
    Beschreibung: A numerical program has been developed to determine the effects on lift interference of the finite length of the slotted portion of a square tunnel. Also analyzed by the program are the effects produced by small variations of static pressure between upper and lower plenum, and by boundary layer development on upper and lower walls downstream of the slotted section. In the flow model, based on compressible linear theory, the wing is represented by a single vortex and the wall induced perturbations are obtained by superimposing the effects of a series of images of the central vortex and of a distribution of sources and sinks on panels along the tunnel walls. The present results can be indicative of the magnitude and of the trends of the interference patterns associated with slotted test sections of finite length at high subsonic Mach numbers.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA-CR-144980
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