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  • Polymer and Materials Science  (2,182)
  • AERODYNAMICS  (415)
  • Life and Medical Sciences  (319)
  • FLUID MECHANICS AND HEAT TRANSFER  (267)
  • Animals
  • 1995-1999
  • 1975-1979  (3,155)
  • 1950-1954
  • 1925-1929  (29)
  • 1975  (3,155)
  • 1925  (29)
Collection
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  • 1995-1999
  • 1975-1979  (3,155)
  • 1950-1954
  • 1925-1929  (29)
Year
  • 1
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    Investigation B: Laminar confined coaxial entrance flow with heat generation (1975)
    In:  CASI
    Details
    Publication Date: 2009-11-16
    Description: The results of a parametric study on the entrance flow region in a gas core nuclear reactor are presented. The physical system is modeled as laminar confined, coaxial flow with heat generation in the inner fluid. The governing equations include the boundary layer approximations and the assumptions of only radial radiative transport of energy represented as an energy diffusion term. The Von Mises transformation and a zeta transformation are used to transform the equations into nonlinear nonhomogeneous convective-diffusion equations. A unique combination of forward and backward difference equations which yields accurate results at moderate computational times, is used in the numerical method. Results show that the rapidly accelerating, heat generating inner stream actually shrinks in radius as it expands axially.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulence Coefficients and Stability Studies for the Coaxial Flow or Dissimiliar Fluids; 76 p
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  • 2
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    Computational aerodynamics (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA/Univ. Conf. on Aeron.; p 211-212
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  • 3
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    On wake vortex alleviation (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA/Univ. Conf. on Aeron.; p 143-168
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  • 4
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    An experimental and numerical investigation of shock wave induced turbulent boundary layer separation at hypersonic speeds (1975)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AGARD Flow Separation; 13 p
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  • 5
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    On the calculation of supersonic separating and reattaching flows (1975)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AGARD Flow Separation; 12 p
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  • 6
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    The transformation of aerodynamic stability derivatives by symbolic mathematical computation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aeronautical Quarterly; 26; May 1975
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  • 7
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    Empirical correlations for heat transfer and flow friction characteristics of rectangular offset-fin plate-fin heat exchangers (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 8
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    The low frequency sound from multipole sources in axisymmetric shear flows, with applications to jet noise (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 70; Aug. 12
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  • 9
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    Inviscid interpenetration of two streams with unequal total pressures (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A theory is proposed for analyzing the inviscid interpretation of two streams in the case when the difference in total pressure between the streams is relatively small. A stream is considered which discharges from a nozzle or reservoir into a partially moving and partially stationary environment in such a way that the flows leave the solid boundaries in a tangential direction where the two streams first interact. The problem is solved by expanding in a small parameter related to the difference in total pressure between the streams, the zeroth-order solution is obtained by classical methods, and a technique similar to that employed in thin-airfoil theory is used to transfer the first-order boundary conditions to the zeroth-order boundary. A procedure is developed to transform the problem into one that can be solved by standard techniques of the theory of sectionally analytic functions. Solutions are obtained for flows with and without free streamlines, and the general theory is applied to several specific flow configurations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 70; Aug. 12
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  • 10
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    Radiation exchange for a system with partially transmitting wall (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An approach is presented for applying the net radiation method developed by Siegel and Howell (1972) and Sparrow and Cess (1966) to systems involving opaque and partially transmitting walls. The results obtained from the basic equations for various values of plate emissivities and temperatures are presented in graphs. Attention is given to the window temperature relative to the temperature of the hot wall and the heat transferred relative to that transferred without the window.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Letters in Heat and Mass Transfer; 2; Mar
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  • 11
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    Derivation and application of the reciprocity relations for radiative transfer with internal illumination (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A Green's function formulation is used to derive basic reciprocity relations for planar radiative transfer in a general medium with internal illumination. Reciprocity (or functional symmetry) allows an explicit and generalized development of the equivalence between source and probability functions. Assuming similar symmetry in three-dimensional space, a general relationship is derived between planar-source intensity and point-source total directional energy. These quantities are expressed in terms of standard (universal) functions associated with the planar medium, while all results are derived from the differential equation of radiative transfer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 15; Sept
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  • 12
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    Radiation from an array of longitudinal fins of triangular profile (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Radiation from an array of longitudinal fins of triangular profile is analyzed, including fin-to-fin and fin-to-base interactions. The effect of base cylinder radiation and the fin-base radiative interaction is found to be significant for fin width/tube radius ratios less than 8. Results presented may be used to optimize the design of a fin array with respect to weight.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; May 1975
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  • 13
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    Comment on 'subsonic and supersonic boundary-layer flow past a wavy wall' (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; Apr. 197
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  • 14
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    Estimates of nonequilibrium radiation for Venus entry (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Apr. 197
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  • 15
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    Comparison of theory and experiment for homogeneous turbulence with shear (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Solutions for uniformly-sheared turbulence, in which the interaction of the turbulence with the mean shear dominates the turbulent self-interaction, are compared with experiment. An anisotropic spectral tensor, which appears general enough to represent the initial experimental turbulence, is used for the initial condition in the calculations. The evolution of one-point turbulence components and microscales, as well as two-point velocity correlations, are considered. In most cases the agreement with experiment is good. The theory correctly predicts the presence of a negative region for two-point longitudinal-velocity correlations only for point separations in the direction normal to the flow and the mean gradient.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 18; Oct. 197
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  • 16
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    Bringing wings of change - NASA's airfoil research program (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Astronautics and Aeronautics; 13; Oct. 197
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  • 17
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    Influence of probe geometry on pitot-probe displacement in supersonic turbulent flow (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An experiment was conducted to determine the varying effects of six different probe-tip and support-shaft configurations on pitot tube displacement. The study was stimulated by discrepancies between supersonic wind-tunnel tests conducted by Wilson and Young (1949) and Allen (1972). Wilson (1973) had concluded that these discrepancies were caused by differences in probe geometry. It is shown that in fact, no major differences in profiles of streamwise velocity over streamwise velocity at boundary-layer edge vs normal coordinate over boundary-layer total thickness result from geometry. The true cause of the discrepancies, however, remains to be discovered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; July 197
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  • 18
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    Flow rates for sharp-edged orifices (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Two charts are proposed for calculating the flow coefficient and the area correction factor used in the equation for the flow rate through a sharp-edged orifice. The proposed charts account for variations in the discharge coefficient of sharp-edged orifices and can be used with any pressure ratio for both subcritical and supercritical flow conditions. They can also be used for any gas by using the appropriate gas constant and ratio of specific heats. The application of the charts is illustrated by examples.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Machine Design; 47; June 12
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  • 19
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    Radiative equilibrium in a rectangular enclosure bounded by gray walls (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Two-dimensional temperature and heat-flux distributions are calculated for an absorbing-emitting gray medium at radiative equilibrium in a rectangular enclosure. The bounding walls are gray and diffuse with arbitrary surface-temperature distributions, and heat generation may take place inside the medium. As a first approximation, the problem is solved for optically thick systems (differential approximation). These results are subsequently improved by the introduction of a number of geometrical parameters to yield good accuracy for all optical thicknesses. As examples, two cases are discussed in detail: (1) uniform heat generation in a black enclosure, and (2) an enclosure with one gray surface at constant temperature. Comparison with some numerical solutions generated by Hottel's /Hottel and Cohen (1958) and Einstein (1963)/ zonal method shows excellent agreement.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 15; June 197
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  • 20
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    Investigation A: Numerical solutions of driven vortices of binary fluid in a cylindrical geometry (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The steady state laminar motion of a viscous, incompressible and binary fluid is studied for a rotating flow in a cylindrical geometry. The mathematical model employed is a cold flow simulation of the fluid mechanics of the light-bulb concept of the gaseous core nuclear engine. A numerical treatment is developed for the rotating flow which includes a description of the nuclear fuel addition. The problem is formulated with the complete Navier-Stokes equations in order to show the interaction between the fuel addition, the main flow, and the boundary layer flow in an accurate manner. The results presented show holdup of the nuclear fuel for the case of steady fuel addition.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulence Coefficients and Stability Studies for the Coaxial flow or Dissimiliar Fluids; 146 p
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  • 21
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    Supersonic Mixing and Combustion in Parallel Injection Flow Fields (1975)
    In:  CASI
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    Publication Date: 2011-01-13
    Description: Adequate prediction techniques for supersonic, mixing, reacting flows are of great importance in the design and performance analysis of supersonic combustion ramjet (scramjet) engines. Analytical programs for parallel injection flow fields with chemical reaction and turbulent mixing are now available for both single and multiple-jet flows. The application of these analyses to simple flow geometries is discussed, and comparisons also are made with data on the more complex case of multiple-jet, reacting flows. A review is given of Langley investigations of parallel injection flow fields. Among these are single-jet studies of nonreacting, turbulent mixing (H2 in air and H2 in N2), and of reacting turbulent mixing (H2 in air) with both single and multiple jets. Implications of the results of the studies for scramjet fuel injector design are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Anal. and Numerical Methods for Invest. of Flow Fields with Chem. Reactions, Especially Related to Combust.; 8 p
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  • 22
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    Higher order accurate difference solutions of fluid mechanics problems by a compact differencing technique (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A general fourth order differencing scheme is developed and applied to three viscous test problems to verify the accuracy and applicability of the technique. The procedure is atypical since only three nodes are necessary to obtain the desired fourth order accuracy. This is accomplished by a differencing technique which considers the function and all necessary derivatives as unknowns. The relations for these derivatives yield simple tridiagonal equations which can be easily solved. Comparisons of the fourth order results with those computed using second order methods are presented for the test problems and clearly indicate that the accuracy achieved by these fourth order computations is always significantly better than current second order procedures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 19; Sept
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  • 23
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    Theoretical study of lift-generated vortex wakes designed to avoid rollup (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Two hypothetical vortex wakes are introduced and studied theoretically to explore whether the rollup of lift-generated vortex sheets can be suppressed. The circulation distribution across each wake is specified such that one rotates and the other translates as a unit due to their self-induced velocities. Several span loadings are constructed from these solutions and the resulting inviscid wake structure is computed for several span lengths behind the generating wing by use of the discrete vortex method wherein the vortex wake is represented by an array of vortices. The final distribution of vortices is then used to estimate the rolling moment on an encountering wing. It is found that, even though the initial specified motions are not sustained, substantial reductions in rolling moment are predicted for certain ranges of the ratio of the span of the generating wing to the following wing.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Apr. 197
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  • 24
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    Relaxation methods in fluid mechanics (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The present work considers the iterative solution of a coupled set of difference equations and examines methods that carry successive approximates to a state that is invariant with further iteration and independent of the initial guess. Methods are studied with regard to their efficiency and economy of computer resources. The basic principles of classical relaxation are set forth, with attention confined to linear elliptic equations. This discussion involves the evaluation of the spectral radius that is the magnitude of the eigenvalue with largest modulus. The subject of relaxation is then related to the study of ordinary differential equations and hyperbolic partial differential equations. Problems that occur when linearly dependent eigenvectors appear in the relaxation matrix are discussed, leading to multiply connected eigenvalues in the Jordan canonical form. Finally, a brief survey of relaxation methods used in aerodynamics is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 25
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    Numerical solutions for supersonic corner flow (1975)
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    Publication Date: 2011-08-16
    Description: Analytical solutions for inviscid supersonic corner flows are virtually nonexistent due to the complexity of the interference geometry. In view of this, numerical solutions for swept-compressive and swept-expansive corner flows are obtained. The governing equations are written in strong conservation-law form and are solved iteratively in nonorthogonal conical coordinates by use of a second-order, shock-capturing, finite-difference technique. The computed wave structure and surface pressure distributions are compared with high Reynolds number experimental data and show very good agreement. The results clearly show that supersonic corner flow at reasonably high Reynolds numbers including the effect of sweep is dominated by the inviscid field.
    Keywords: AERODYNAMICS
    Type: Journal of Computational Physics; 17; Feb. 197
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  • 26
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    Measured three-dimensional effects in transonic airfoil testing (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An investigation was conducted regarding the issue of deviation from two-dimensionality in flowfield studies of a supercritical airfoil. It was found that significant three-dimensional effects occur in transonic airfoil tests, even for an aspect ratio of four. This is especially true at the supercritical Mach numbers, for which lateral propagation of disturbances is effective.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Feb. 197
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  • 27
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    Aerodynamic characteristics of the planetary atmosphere experiments test entry probe (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The aerodynamic characteristics of the Planetary Atmosphere Experiments Test entry probe were determined experimentally in ballistic range tests over a wide range of Mach and Reynolds numbers, and were compared with full-scale flight results. The ground facility data agreed with the full-scale data within 2 to 3% in drag coefficient, and within 5 to 10% in static stability, at the higher Mach numbers. Comparisons of the flight data with conventional wind-tunnel data indicated a significant disagreement in drag coefficient in the transonic speed range suggestive of important sting or wall interference effects. Variations in drag coefficient with Mach number were very small hypersonically, but variations with Reynolds number were of the order of 15% at a free-stream Mach number of 13 over the Reynolds number range from 10,000 to 1,000,000. Variations in the lift and static-stability curves with Mach number and Reynolds number were also defined.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Jan. 197
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  • 28
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    Turbulence stress measurements in a nonadiabatic hypersonic boundary layer (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Turbulent shear stress and direct turbulent total heat-flux measurements have been made across a nonadiabatic, zero pressure gradient, hypersonic boundary layer by using specially designed hot-wire probes free of strain-gauging and wire oscillation. Heat-flux measurements were in reasonably good agreement with values obtained by integrating the energy equation using measured profiles of velocity and temperature. The shear-stress values deduced from the measurements, by assuming zero correlation of velocity and pressure fluctuations, were lower than the values obtained by integrating the momentum equation. Statistical properties of the cross-correlations are similar to corresponding incompressible measurements at approximately the same momentum-thickness Reynolds number.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; Dec. 197
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  • 29
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    On the computation of two- and three-dimensional steady transonic flows by relaxation methods (1975)
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    Publication Date: 2011-08-16
    Description: The paper is concerned with the application of the Murman and Cole (1971) relaxation scheme to steady, inviscid transonic flow problems in two and three dimensions. This scheme, which automatically accounts for weak shock waves, uses separate difference operators in elliptic and hyperbolic regions. The details of the scheme are described in terms of the original small disturbance formulation of Murman and Cole. In particular, Murman's recent (1973) introduction of fully conservative difference operators to obtain the correct shock jumps is examined. The extension to treating the exact isentropic equation is then covered with special attention given to Jameson's (to appear) rotated difference scheme for supersonic flow regions. The bulk of the discussion is related to two-dimensional procedures, and some comparisons with experiment are made, with emphasis on the effects of viscosity and wind-tunnel walls. Application of the Murman-Cole scheme is then discussed for small disturbances in three dimensions.
    Keywords: AERODYNAMICS
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  • 30
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    Multiple slot skin friction reduction (1975)
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    Publication Date: 2011-08-16
    Description: The paper investigates analytically the effect of multiple slot injection on skin friction for a representative fuselage shape (ogive-cylinder body) and evaluates the potential of slot injection as a drag reduction system in subsonic flow. Typical CTOL cruise flight conditions (Mach number equals 0.82 at altitudes of 11 km) were adopted for a fuselage 67.06 m in length and with maximum diameter of 7.32 m. The numerical method of Price and Harris (1972) was used to calculate the boundary-layer characteristics up to the first slot, while the finite-difference method of Beckwith and Bushnell (1971) was used to calculate the velocity profile downstream of one, three, five, or ten slots. An integral expression is proposed for characterizing skin friction reduction effectiveness, and it is seen that large reductions in viscous drag (50%) are available through slot injection. Skin friction reduction is improved by increasing the number of injection slots but at a diminishing rate.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 31
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    Mach and Reynolds number effects on turbulent skin friction reduction by injection (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The investigation reported is concerned with questions regarding a possible Mach number influence on skin friction reduction caused by injection. The investigation shows that data considered by Danberg (1967) for the no-blowing skin friction coefficient are in error. Accurate profiles and local skin friction coefficient values are obtained when the influence of low Reynolds number amplification in the outer region of the boundary layer is included in a calculation method.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Aug. 197
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  • 32
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    Cascade with subsonic leading-edge locus (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The paper investigates a two-dimensional oscillating cascade with a subsonic leading edge locus in a supersonic flow. The blades are assumed to be of small thickness and camber, and are undergoing small amplitude-harmonic oscillations. The problem is reduced to the solution of a functional integral equation, and an expression is given for the kernel function.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Aug. 197
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  • 33
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    The flow over a 'high' aspect ratio gothic wing at supersonic speeds (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.
    Keywords: AERODYNAMICS
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  • 34
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    On the analytic structure of the Taylor-Maccoll conical-flow solution (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The conical flow solution for axisymmetric supersonic flow past cones has been found to be virtually independent of the ratio of specific heats when normalized in a certain way. A simple rational approximation to this flow is derived. The important singularities and the limiting behavior of the solution are also discussed.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer angewandte Mathematik und Physik; 26; July 25
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  • 35
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    Supersonic inlet contour interpolation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A method for designing supersonic inlet contours is described which consists in the interpolation of the contours of two known inlets designed for different Mach numbers, thereby determining the contours for a third inlet at an intermediate design Mach number. Several similar axisymmetric inlet contours were interpolated from known inlets with design Mach numbers ranging from 2.16 to 4.0 and with design Mach numbers differing by as much as 1.0. The flowfields were calculated according to Sorensen's (1965) computer program. Shockwave structure and pressure distribution characteristics are shown for the interpolated inlets. The validity of the interpolation is demonstrated by comparing the plots of the flowfield properties across the throat station of the interpolated inlet with the known inlets which were designed iteratively. It seems possible to write a computer program so that a matrix of known inlet contours can be interpolated.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 36
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    Experimental verification of turbulent skin friction reduction with compliant walls (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Preliminary compliant wall skin friction test results obtained in a low-turbulence pressure tunnel are reported. Compliant surface skins consisted of 0.0025 cm thick mylar, stretched under tension and area-bonded or longitudinally strip-bonded with silicone rubber adhesive to polyurethane foam. Mean velocity and fluctuating survey data were obtained with a single slanted hot wire. Mean velocity profiles for the area-bonded mylar surface skins indicated up to a 20% reduction in boundary-layer thickness (and lower momentum thickness) over rigid surfaces. This reduction in boundary-layer thickness indicates that a drag reduction occurred. In addition, a 16% reduction in wall shear was evident for the mylar/compressor foam compliant surface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; July 197
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  • 37
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    Stability characteristics of a single-phase free convection loop (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Experiments investigating the stability characteristics of a single-phase free convection loop are reported. Results of the study confirm the contention made by previous workers that instabilities near the thermodynamic critical point can occur for ordinary fluids as well as those with unusual behavior in the near-critical region. Such a claim runs counter to traditional beliefs, but it is supported by the observation of such instabilities for water at atmospheric pressure and moderate temperatures in the present work.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 67; Jan. 14
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  • 38
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    Computation of three-dimensional, inviscid supersonic flows (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
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  • 39
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    Drag coefficient equations for small particles in high speed flows (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The paper determines the effect of various available drag coefficient equations on particle velocity calculations for typical two phase flows encountered in supersonic and turbulent laser velocimeter applications. The predictions of the particle drag coefficient equations are compared with experimental sphere drag data. For the laser velocimeter applications, the relative Mach number less than 2 and the relative Reynolds number less than 200 are of particular importance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; Nov. 197
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  • 40
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    Series solution for the planar asymmetric blunt-body problem (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Physics of Fluids; 18; Dec. 197
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  • 41
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    Hypersonic incipient separation on delta wing with trailing-edge flap (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Oct. 197
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  • 42
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    Mixing length in low Reynolds number compressible turbulent boundary layers (1975)
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    Publication Date: 2011-08-16
    Description: The paper studies the effect of low Reynolds number in high-speed turbulent boundary layers on variations of mixing length. Boundary layers downstream of natural transition on plates, cones and cylinders, and boundary layers on nozzle walls without laminarization-retransition are considered. The problem of whether low Reynolds number amplification of shear stress is a result of transitional flow structure is considered. It is concluded that a knowledge of low Reynolds number boundary layer transition may be relevant to the design of high-speed vehicles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 13; Aug. 197
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  • 43
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    Forward marching procedure for separated boundary-layer flows (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Aug. 197
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  • 44
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    An experimental study of jet exhaust simulation (1975)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AGARD Airframe(Propulsion Interference; 11 p
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  • 45
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    Contribution of the National Aeronautics and Space Administration Langley Research Center (1975)
    In:  CASI
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    Publication Date: 2012-05-19
    Description: As part of a special international effort, three nozzles were designed and tested on single nacelle models in wind tunnels of several nations belonging to the North Atlantic Treaty Organization. All three of these nozzles were investigated in the Langley 16-foot transonic wind tunnel at the National Aeronautics and Space Administration's Langley Research Center. Langley Research Center also contributed theoretical calculations of the jet plume boundary and afterbody pressures. The calculations were obtained using an iterative solution which combined the inviscid Douglas Neumann method for the external flow with the method of characteristics for the flow in the jet plume. For the investigation, the nozzles were mounted on a single nacelle model 15.24 centimeters in diameter and 162.56 centimeters long. Tests were made at free stream Mach number from 0.4 to 1.2, and at Reynolds numbers per meter from 7.38 million to 13.78 million depending on the Mach number. Four types of data were recorded: afterbody pressure data, afterbody force data, model boundary layer data, and tunnel wall pressure data. The ratio of jet total pressure to free stream static pressure ranged up to 8.5. A description of the wind tunnel, model, and test procedure is included.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Improved Nozzle Testing Tech. in Transonic Flow; 9 p
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  • 46
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    Reynolds number effects on boattail drag of exhaust nozzles from wind tunnel and flight tests (1975)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AGARD Airframe(Propulsion Interference; 15 p
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  • 47
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    Numerical techniques for the solution of the compressible Navier-Stokes equations and implementation of turbulence models (1975)
    In:  CASI
    Details
    Publication Date: 2012-05-19
    Description: The time-splitting explicit numerical method of MacCormack is applied to separated turbulent boundary layer flow problems. Modifications of this basic method are developed to counter difficulties associated with complicated geometry and severe numerical resolution requirements of turbulence model equations. The accuracy of solutions is investigated by comparison with exact solutions for several simple cases. Procedures are developed for modifying the basic method to improve the accuracy. Numerical solutions of high-Reynolds-number separated flows over an airfoil and shock-separated flows over a flat plate are obtained. A simple mixing length model of turbulence is used for the transonic flow past an airfoil. A nonorthogonal mesh of arbitrary configuration facilitates the description of the flow field. For the simpler geometry associated with the flat plate, a rectangular mesh is used, and solutions are obtained based on a two-equation differential model of turbulence.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Computational Methods for Inviscid and Viscous Two-and-Three-Dimensional Flow Fields; 24 p
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  • 48
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    An aerodynamic load criterion for airships (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 169-176
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  • 49
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    Overview of external Nacelle drag and interference drag (1975)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 235-244
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  • 50
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    Computational aspects of the prediction of multidimensional transonic flows in turbomachinery (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 567-585
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    Simulation of turbulent transonic separated flow over an airfoil (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 419-436
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  • 52
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    On the calculation of supersonic, separating, and reattaching flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 151-175
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  • 53
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    Internal and external axial corner flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 643-658
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  • 54
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    Numerical computation of viscous flows on the lee side of blunt shapes flying at supersonic speeds (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 531-542
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  • 55
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    Long fluid filled bags suspended by line forces (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 199-208
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  • 56
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    The planar dynamics of airships (1975)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 177-186
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  • 57
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    General overview of drag (1975)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 11-37
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  • 58
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    Drag of the complete configuration aerodynamic considerations, 2 (1975)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 337-351
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  • 59
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    Trim Drag in the Light of Munk's Stagger Theorem (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 319-329
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  • 60
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    Wing Tip Vortex Drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 215-233
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  • 61
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    Preservation of wing leading edge suction at the plane of symmetry as a factor in wing-fuselage design (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 107-115
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  • 62
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    Prospects and time tables for analytical estimation of the drag of complete aircraft configuration (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Analytical drag methods and wind tunnel evaluation of aircraft design features are used to identify excessive drag of general aviation aircraft with reciprocating engines.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 39-41
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  • 63
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    Summary of drag clean-up tests in NASA Langley full-scale tunnel (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-60
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  • 64
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    An investigation of several numerical procedures for time-asymptotic compressible Navier-Stokes solutions (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 437-468
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  • 65
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    Subgrid or Reynolds stress-modeling for three-dimensional turbulence computations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 317-339
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  • 66
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    Solutions for incompressible separated boundary layers including viscous-inviscid interaction (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 125-150
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  • 67
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    A comparison of a shock-capturing technique with experimental data for three-dimensional internal flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 623-642
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  • 68
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    Calculation of three-dimensional compressible laminar and turbulent boundary layers. Calculation of three-dimensional compressible boundary layers on arbitrary wings (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 41-76
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  • 69
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    Calculation of supersonic three-dimensional free-mixing flows using the parabolic-elliptic Navier-Stokes equations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 543-565
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  • 70
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    Calculation of shock-separated turbulent boundary layers (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 401-417
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  • 71
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    Influence of external disturbances and compressibility on free turbulent mixing (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 341-376
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  • 72
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    Minimum Vertical Tail Drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Tail size requirement calculations are presented for a vertical tail performing a coordinated turn reversal at corresponding load requirements with minimum tail drag.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-446
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  • 73
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    Some comments on trim drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 295-305
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  • 74
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    Nacelle drag reduction: An analytically-guided experimental program (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 257-261
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  • 75
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    Asymptotic analytical methods in fluid mechanics related to drag prediction (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Some recent theoretical work of a purely analytical nature is described which promises to provide engineering predictions for the important drag-related phenomena of flow in the stall regime. This analytical work deals with rigorous asymptotic studies of the complete Navier-Stokes equations that govern the viscous flow around any aerodynamic body under conditions where boundary layer separation takes place from the body surface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 117-124
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  • 76
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    Time-dependent transonic flow solutions for axial turbomachinery (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 587-621
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  • 77
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    Calculation of three-dimensional compressible laminar and turbulent boundary flows. Three-dimensional compressible boundary layers of reacting gases over realistic configurations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 77-99
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  • 78
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    Calculation of three-dimensional compressible laminar and turbulent boundary layers. An implicit finite-difference procedure for solving the three-dimensional compressible laminar, transitional, and turbulent boundary-layer equations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 17-40
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  • 79
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    A numerical determination of the bow shock wave in transonic axisymmetric flow about blunt bodies (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-72448 , NRC-14765 , LR-586 , (ISSN 0077-5541)
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  • 80
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    Wind tunnel investigation of an oblique wing transport model at mach numbers between 0.6 and 1.4 (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-CR-137697 , HST-TR-344-0
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  • 81
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    Transonic aerodynamic characteristics of the 10-percent-thick NASA supercritical airfoil 31 (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-3203 , L-9841 , NAS 1.15:X-3203
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  • 82
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    Static longitudinal aerodynamic characteristics of a model with a modified 17 percent thick supercritical wing (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-3211 , L-9960 , NAS 1.15:X-3211
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  • 83
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    Tabulated pressure measurements on an executive-type jet transport model with a supercritical wing (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-72701 , NAS 1.15:X-72701
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  • 84
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    Effects of landing gear, speed brake and protuberances on the longitudinal aerodynamic characteristics of an NASA supercritical-wing research airplane model (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-72684 , NAS 1.15:X-72684
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  • 85
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    Viscous flow solutions with a cubic spline approximation (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A cubic spline approximation is used for the solution of several problems in fluid mechanics. This procedure provides a high degree of accuracy even with a nonuniform mesh, and leads to a more accurate treatment of derivative boundary conditions. The truncation errors and stability limitations of several typical integration schemes are presented. For two-dimensional flows a spline-alternating-direction-implicit (SADI) method is evaluated. The spline procedure is assessed and results are presented for the one-dimensional nonlinear Burgers' equation, as well as the two-dimensional diffusion equation and the vorticity-stream function system describing the viscous flow in a driven cavity. Comparisons are made with analytic solutions for the first two problems and with finite-difference calculations for the cavity flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computers and Fluids; 3; Mar. 197
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  • 86
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    Numerical calculation of finite amplitude effects in unstable laminar boundary layers (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A numerical study of one stage of the transition region from laminar to turbulent flow of the boundary layer over a flat plate is performed. Benney-Lin theory is applied to the laminar profile, which is closer to that of the experiment, i.e., the Blasius profile. Several laminar profiles are studied, all belonging to the Falkner-Skan family. The flow is found to depend principally upon the disturbance spanwise wavenumber, beta, whose variation results, in some instances, in a system of counter-rotating vortices, one on top of the other, for the mean secondary flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 18; Mar. 197
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  • 87
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    Reduction of wind tunnel wall interference by controlled wall flow (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An alternate method of testing was developed in which flow through the porous walls of the tunnel was actively controlled so as to approximate free air conditions in the neighborhood of the model during the test. The amount and distribution of the controlled flow through the walls is computed using a potential flow representation of the model based on the measured lift. Theoretical analysis is presented to prove the convergence of the method to free air conditions and to substantiate the general three-dimensional theory of operation when the normal flow distribution is continuous. A two-dimensional tunnel was constructed to evaluate the concept. Results show that substantial reduction of wall interference may be achieved with relatively low values of porosity of actively controlled walls.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-119090
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  • 88
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    Analysis of screeching in a cold flow jet experiment (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The screech phenomenon observed in a one-sixtieth scale model space shuttle test of the solid rocket booster exhaust flow noise has been investigated. A critical review is given of the cold flow test data representative of Space Shuttle launch configurations to define those parameters which contribute to screech generation. An acoustic feedback mechanism is found to be responsible for the generation of screech. A simple equation which permits prediction of screech frequency in terms of basic testing parameters such as the jet exhaust Mach number and the separating distance from nozzle exit to the surface of model launch pad is presented and is found in good agreement with the test data. Finally, techniques are recommended to eliminate or reduce the screech.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-143943 , WR-75-2
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  • 89
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    A momentum analysis of helicopters and autogyros in inclined descent, with comments on operational restrictions (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TN-D-7917 , L-10045
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  • 90
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    Experimental study of a free turbulent shear flow at Mach 19 with electron-beam and conventional probes (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental study of the initial development region of a hypersonic turbulent free mixing layer was made. Data were obtained at three stations downstream of a M = 19 nozzle over a Reynolds range of 1.3 million to 3.3 million per meter and at a total temperature of about 1670 K. In general, good agreement was obtained between electron-beam and conventional probe measurements of local mean flow parameters. Measurements of fluctuating density indicated that peak root-mean-square (rms) levels are higher in the turbulent free mixing layer than in boundary layers for Mach numbers less than 9. The intensity of rms density fluctuations in the free stream is similar in magnitude to pressure fluctuations in high Mach number flows. Spectrum analyses of the measured fluctuating density through the shear layer indicate significant fluctuation energy at the lower frequencies (0.2 to 5 kHZ) which correspond to large-scale disturbances in the high-velocity region of the shear layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TN-D-7981 , L-10138
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  • 91
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    A Three-Dimensional Solution of Flows over Wings with Leading-Edge Vortex Separation. Part 2: Program Description Document (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: For abstract, see N75-32026.
    Keywords: AERODYNAMICS
    Type: NASA-CR-132710 , D6-41789-PT-2
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  • 92
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    Fire safety evaluation of aircraft lavatory and cargo compartments (1975)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-62471 , A-6235
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  • 93
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    A Three-Dimensional Solution of Flows over Wings with Leading-Edge Vortex Separation. Part 1: Engineering Document (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-CR-132709 , D6-41789-PT-1
    Format: application/pdf
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  • 94
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    Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2595 , FTAS/TR-75-100
    Format: application/pdf
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  • 95
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    Analysis of helicopter rotor blade torsional oscillations due to stall (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2573
    Format: application/pdf
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  • 96
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    Strain-gage bridge calibration and flight loads measurements on a low-aspect-ratio thin wing (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TN-D-7979 , L-9896
    Format: application/pdf
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  • 97
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    Wind tunnel investigation of a large-scale upper surface blown-flap model having four engines (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-62419 , A-6003
    Format: application/pdf
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  • 98
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    Experimental evaluation of joint designs for a space-shuttle orbiter ablative leading edge (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The thermal performance of two types of ablative leading-edge joints for a space-shuttle orbiter were tested and evaluated. Chordwise joints between ablative leading-edge segments, and spanwise joints between ablative leading-edge segments and reusable surface insulation tiles were exposed to simulated shuttle heating environments. The data show that the thermal performance of models with chordwise joints to be as good as jointless models in simulated ascent-heating and orbital cold-soak environments. The suggestion is made for additional work on the joint seals, and, in particular, on the effects of heat-induced seal-material surface irregularities on the local flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-X-3230 , L-10020
    Format: application/pdf
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  • 99
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    Flat plate electrohydrodynamic heat pipe experiments (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Performance capabilities of electrohydrodynamic (EHD) flat heat pipes were investigated using Freon 113 and Freon 11 as working fluids. All of the pipes employed straight rod electrodes to form axial liquid flow channels and tranverse grooves for capillary surface wetting. Results show: (1) the EHD pipe will prime under load, (2) voltage controlled conductance can be achieved by varying the active area of the evaporator, and (3) the average evaporator conductances measured in these experiments were consistent with those obtained in other experiments with heat pipes of similar surface geometry using the same or similar working fluids.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-137707
    Format: application/pdf
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  • 100
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    Viscous interaction of flow redevelopment after flow reattachment with supersonic external streams (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: 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.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Dec. 197
    Format: text
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