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  • FLUID MECHANICS  (1,814)
  • 1970-1974  (1,203)
  • 1960-1964  (611)
  • 1950-1954
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  • 1
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    The Coanda effect in gas-dynamic noise control (1974)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: The principle types of silencers are discussed for gas dynamic noise of free steam and gas expansions, as well as the results of research in gas dynamics of jets and applied acoustics. Gas dynamic noise attenuation by means of the Coanda effect is due to fluid decompression in a Coanda ejector of the external type, where a structural change takes place in the acoustic frequency spectrum and in its direction, as well as a substantial decrease in the fluid's velocity, temperature and concentration. This process is continued in the second phase with absorption of the acoustic waves by means of an active structure.
    Keywords: FLUID MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 143-149
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  • 2
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    New diagnostic technique for the study of turbulent boundary-layer separation (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Description of a diagnostic technique for determining the unsteady character of turbulent boundary-layer separation. The technique uses thin platinum films mounted flush with the model surface. Voltages from these films provide measurements related to the flow character above the film. For illustration, results obtained by this technique are presented for the interaction of a hypersonic shock wave and a turbulent boundary layer, with and without separation.
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 12; Oct. 197
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  • 3
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    Reynolds-shear-stress measurements in a compressible boundary layer within a shock-wave-induced adverse pressure gradient (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS
    Type: Journal of Fluid Mechanics; 65; Aug. 12
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  • 4
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    Evolution of a moderately short turbulent boundary layer in a severe pressure gradient (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The early and intermediate development of a highly accelerated (or decelerated) turbulent boundary layer is analyzed. For sufficiently large accelerations (or pressure gradients) and for total normal strains which are not excessive, the equation for the Reynolds shear stress simplifies to give a stress that remains approximately constant as it is convected along streamlines. The theoretical results for the evolution of the mean velocity in favourable and adverse pressure gradients agree well with experiment for the cases considered. A calculation which includes mass injection at the wall is also given.
    Keywords: FLUID MECHANICS
    Type: Journal of Fluid Mechanics; 64; July 24
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  • 5
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    Turbulent diffusion with memories and intrinsic shear (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The first part of the present theory is devoted to the derivation of a Fokker-Planck equation. The eddies smaller than the hydrodynamic scale of the diffusion cloud form a diffusivity, while the inhomogeneous, bigger eddies give rise to a nonuniform migratory drift. This introduces an eddy-induced shear which reflects on the large-scale diffusion. The eddy-induced shear does not require the presence of a permanent wind shear and is intrinsic to the diffusion. Secondly, a transport theory of diffusivity is developed by the method of repeated-cascade and is based upon a relaxation of a chain of memories with decreasing information. The full range of diffusion consists of inertia, composite, and shear subranges, for which variance and eddy diffusivities are predicted. The coefficients are evaluated. Comparison with experiments in the upper atmosphere and oceans is made.
    Keywords: FLUID MECHANICS
    Type: Zeitschrift fuer Naturforschung; vol. 29a
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  • 6
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    On numerical methods to impose asymptotic boundary conditions of boundary-layer equations (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The error minimization method proposed by Nachtsheim and Swigert (1965) to satisfy the asymptotic boundary conditions of boundary layer equations is proved to be equivalent to imposing the condition of fastest decay. As a consequence, a uniqueness problem is not arising in the solutions of boundary layer equations obtained by their method.
    Keywords: FLUID MECHANICS
    Type: Computers and Fluids; 2; Mar. 197
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  • 7
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    Method for producing a uniform, low Reynolds number jet (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: In one attempt to produce a simple inexpensive nozzle, a 2-in. diam plate with 37 holes was investigated (Stadler, 1960), anticipating that the small jets emanating from the plate would combine to form a uniform stream. This experiment was unsuccessful because a uniform flow was not established until the flow had progressed many nozzle diameters downstream. However, an extension of this concept to a much larger number of very small jets, viz., a porous plate, did provide a method for producing a uniform, low Reynolds number jet almost immediately downstream of the nozzle (Greene, 1973). The method is described and some typical jet velocity profiles for nozzle Reynolds numbers from 50 to 1000 are given.
    Keywords: FLUID MECHANICS
    Type: Journal of Spacecraft and Rockets; 11; Aug. 197
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  • 8
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    Approach to the origin of turbulence on the basis of two-point kinetic theory (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Equations for the fluctuation correlation in an incompressible shear flow are derived on the basis of kinetic theory, utilizing the two-point distribution function which obeys the BBGKY hierarchy equation truncated with the hypothesis of 'ternary' molecular chaos. The step from the molecular to the hydrodynamic description is accomplished by a moment expansion which is a two-point version of the thirteen-moment method, and which leads to a series of correlation equations, viz., the two-point counterparts of the continuity equation, the Navier-Stokes equation, etc. For almost parallel shearing flows the two-point equation is separable and reduces to two Orr-Sommerfeld equations with different physical implications.
    Keywords: FLUID MECHANICS
    Type: Physics of Fluids; 17; Jan. 197
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  • 9
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    Computation of steady nozzle flow by a time-dependent method (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The equations of motion governing steady, inviscid flow are of a mixed type, that is, hyperbolic in the supersonic region and elliptic in the subsonic region. These mathematical difficulties may be removed by using the so-called time-dependent method, where the governing equations become hyperbolic everywhere. The steady-state solution may be obtained as the asymptotic solution for large time. The object of this research was to develop a production type computer program capable of solving converging, converging-diverging, and plug two-dimensional nozzle flows in computational times of 1 min or less on a CDC 6600 computer.
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 12; Apr. 197
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  • 10
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    Flow properties in expansion tube with helium, argon, air, and CO2 (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Test flow velocities from 5 to 7 km/sec were generated in a 6-in. expansion tube using helium, argon, air, and CO2 test gases. Pitot pressure profiles across the flow at the test section are presented for the four test gases, and measured flow quantities are compared to computer predicted values. Comparison of predicted and measured flow quantities suggests the expansion to be near thermochemical equilibrium for all test gases and implies the existence of a totally reflected shock at the secondary diaphragm. Argon, air, and CO2 flows were observed to attenuate while traversing the acceleration section, whereas no attenuation was observed for helium.
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 12; Apr. 197
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  • 11
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    Non-equilibrium ionized blast wave (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The structure of a cylindrical blast wave with ionization at non-LTE conditions was calculated using equations previously developed by Wu and Fu (1970). The degree of ionization was predicted by a modified Saha equation. Temperature profiles show that the temperature at non-LTE conditions is lower than at LTE near the shock front. This corresponds to a higher degree of ionization for the non-LTE limit, which indicates that the neutral gas absorption is much more efficient at non-LTE than at the LTE limit. The decaying velocity under non-LTE is approximately 15% less than under LTE.
    Keywords: FLUID MECHANICS
    Type: Physical Society of Japan; vol. 36
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  • 12
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    Remarks on the decay of homogeneous turbulence from a given state (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A previous theory which did not require a usual closure assumption required three or more initial spectra. By allowing a simple physical assumption (a modification of Kovasznay's (1948) hypothesis), the required number of spectra is reduced to two. Agreement with experiment is good.
    Keywords: FLUID MECHANICS
    Type: Physics of Fluids; 17; Mar. 197
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  • 13
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    Progress and problems in erosion prediction (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Methods for predicting erosion resulting from repeated localized impulsive loadings, such a impacts from droplets or in cavitation flow from microjets and bubbles, are examined. The parameters which determine the adequacy of a component to resist the loads put upon it are identified. The development of erosion rate models is discussed. The expected accuracy of the prediction and the sources of error are analyzed.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failure; p 107-114
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  • 14
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    Effects of viscoelasticity on cavitation in drag reducing fluids (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: To study cavitation inception in polymer solutions, a blow-down water tunnel with short running times was used. Tests were made using 1/4 and 1/2 inch diameter models of hemispherical-nose cylinders. To accurately detect the inception of cavitation, a reliable technique was developed using a continuously operating He-Ne gas laser. The laser beam was adjusted to grazing incidence with the model at the minimum pressure point where cavitation inception was to be expected. A sensitive photocell was placed at ninety degrees to detect the beam. As incipient cavitation occurred, the bubbles caused scattering of the laser beam which was picked up by the photocell. Static pressure near the model in the working section of the tunnel was measured using a solid-state pressure pick-up. The signals from the photocell and the pressure pick-up were recorded on an oscillograph. Velocity field visualization was achieved using one microsecond duration light pulses scattered by small polystryrene latex spheres in the flow.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 100-106
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  • 15
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    Effect of cavitation on fluid stability in polymer thickened fluids and lubricants (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The effects of cavitating flow on the polymeric additives used in functional fluids are described. A comparison of thermal and mechanical stability tests for these polymer solutions show distinct differences in the machanism of the polymer degradation. The thermal degradation tests appear to cause an unzippering or depolymerization type of reaction in which there is no particular selectivity based on molecular weight. The mechanical degradation of these fluids appears to be based on molecular weight. Measurements of molecular weight distributions during mechanical degradation show that for a given level of intensity only molecules above a certain minimum size are degraded. The effects of ultrasonic radiation on polymer degradation are reported. Tests were conducted to demonstrate the mechanism of mechanical polymer degradiation in an orifice. A more severe test than the orifice test in which two tapered roller bearings loaded against each other produce the mechanical breakdown is discussed.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 88-99
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  • 16
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    Lubricant pressure rippling in dynamic Hertzian contacts induced by surface roughness (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A numerical analysis of the pressure distribution of a lubricant in contact with a rough surface was conducted. The magnitude of the pressures was determined by their root mean square value for the contact of two dimensional cylinders. The pressure was found to vary in the following manner: (1) the location in the contact, (2) the spectrum or frequency content of the surface roughness, (3) the mean plateau film thickness, and (4) the root mean square value of the surface roughness. Mathematical models are developed to show the relationships of the parameters.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 62-73
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  • 17
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    Examples of oil cavitation erosion in positive displacement pumps (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The effects of cavitation flow on piston type, positive displacement, hydraulic pumps are discussed. The operating principles of the pump and the components which are most subject to erosion effects are described. The mechanisms of cavitation phenomena are identified from photographic records. Curves are developed to show the solubility of air in water, oil-water emulsion, and industrial hydraulic oil.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 48-53
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  • 18
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    Some practical examples of cavitation erosion and their prevention (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The problem of failures caused by cavitation erosion are discussed. The concepts of intensity of erosion, erosion strength, and the time dependence of erosion rate are analyzed. The relation of these parameters to system variables such as pressure and velocity, and to the properties of materials are investigated. Using several examples of actual cavitation erosion, methods of prevention and their limitations are examined.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 39-47
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  • 19
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    Recent theories of cavitation damage including non-symmetrical bubble collapse effects (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Theories of cavitation damage mechanisms are discussed. Photographic evidence has shown that the actual collapse of bubbles near a symmetry-destroying feature such as a nearby wall results in a toroidal-like collapse, with the final generation of a liquid microjet oriented toward the wall. Numerical analyses indicate that the shock wave intensity emitted during collapse is not likely to be strong enough to be damaging to most materials. It has been determined that actual damage is usually a result of a combination of impact effect of the microjet and the shock wave pressures generated by bubble rebounds.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 31-35
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  • 20
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    The role of mechanical properties in cavitation erosion resistance (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Methods for determining the correlations of erosion resistance and mechanical properties of materials are discussed. The most common method of testing cavitation erosion resistance of materials is the vibratory cavitation probe. The instrument and its operation are described. The use of the whirling arm device is considered as a second method. Metallographic investigations of the earliest stages of cavitation erosion damage of metallic materials was conducted. The materials show plastic deformation occurring during the incubation period and increasing until cracks form and metal fragments are lost. The parameters of the work done to cause material fractures are identified. The reactions obtained with specific materials are reported.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 23-30
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  • 21
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    Role of physical properties of liquids in cavitation erosion (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The dependence of erosion rates on the ambient temperature of water is discussed. The assumption that the gas inside the bubble is compressed adiabatically during collapse gives better agreement with experiments than the assumption that the gas is isothermally compressed. Acoustic impedance is an important liquid parameter that governs the erosion intensity in vibratory devices. The investigation reveals that the major physical properties of liquids governing the intensity of erosion include density, sound speed, surface tension, vapor pressure, gas content, and nuclei distribution.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 13-22
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  • 22
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    Physics associated with cavitation induced material damage (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The role of cavitation in mechanical failure is discussed. Some of the most common types of material damage associated with the presence of cavitation are surface material removal, delamination and structural vibration. This occurs in external flows such as on propellers, hydrofoils, and high speed non-lifting surfaces. In internal flows, pipe bends, inlets, constructions, pumps and turbines are typical. Nominally nonflowing liquids are also susceptible in, for example, strong acoustic fields and high energy particle detectors. For flowing systems, Bernoulli's equation shows how a local pressure is reduced as the fluid's velocity is increased. At sufficiently high velocities, a tension can actually develop and this has, in fact, been demonstrated experimentally. Once the pressure is reduced below the fluid vapor pressure a vapor cavity can be nucleated. Various aspects of this process are simply shown by considering the flow over a lifting surface.
    Keywords: FLUID MECHANICS
    Type: NBS The Role of Cavitation in Mech. Failures; p 3-12
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  • 23
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    Wall shear in strongly retarded and separated compressible turbulent boundary layers (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 12; Oct. 197
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  • 24
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    Experimental study of the shock-induced unsteady laminar boundary layer on a flat plate (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The behavior of the unsteady laminar boundary layer induced by the incident shock wave passing over a flat plate mounted in a shock tube has been experimentally studied for shock speeds ranging from 2.35 to 7.34 km/sec by measuring unsteady heat transfer rates to the plate using thin-film heat-flux gages. Theoretical heat-transfer rates were predicted from analytical solutions in the literature which describe the unsteady flat plate boundary layer development for equilibrium real-gas flows. Experimental results obtained for both air and nitrogen were found to be in good agreement with the theoretical predictions.
    Keywords: FLUID MECHANICS
    Type: Physics of Fluids; 17; May 1974
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  • 25
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    Conservation equations of gasdynamics in curvilinear coordinate systems (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Description of a new method of writing the conservation equations of gasdynamics in curvilinear coordinates which eliminates undifferentiated terms. It is thus possible to readily apply difference schemes derived for Cartesian coordinates which conserve mass, momentum, and energy in the total flow field. The method is derived for orthogonal coordinates, and then extended to cover the most general class of coordinate transformations, using general tensor analysis. Several special features of the equations are discussed.
    Keywords: FLUID MECHANICS
    Type: Journal of Computational Physics; 14; Feb. 197
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  • 26
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    Comments on Crocco's solution and the independence principle for compressible turbulent boundary layers (1974)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The purpose of the present note is to show that on a flat plate where both the wall temperature and mean wall pressure are constant, neither of the limitations of parallel flow or of unity for the turbulent Prandtl number are required in order for the Crocco solution to apply to the turbulent boundary-layer flow. It is shown herein that this result is subject to restrictions on the magnitude of pressure fluctuations. The same analysis is generalized to show that the compressible turbulent boundary layer on an isothermal swept flat plate is independent of the spanwise flow if the molecular Prandtl number is unity.
    Keywords: FLUID MECHANICS
    Type: AIAA Journal; 12; Feb. 197
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  • 27
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    Studies of liquid floating zones on SL-IV, the third Skylab mission (1974)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: The behavior of liquid floating zones in a zero-gravity environment was studied by Dr. E. Gibson on SL-4. These experiments were designed from the results of previous work on floating zones in a simulated zero-gravity model. Molten floating zones are used on earth for the crystal growth and zone refining of reactive materials. The Skylab studies give some insight into the problems associated with the development of the technique for the future space processing of materials. Preliminary results are presented on the stability of the liquid zone surface under static, rotational and vibrational conditions without gravitational constraints.
    Keywords: FLUID MECHANICS
    Type: NASA. Marshall Space Flight Center Proc. of the 3d Space Processing Symp. on Skylab Results, Vol. 2; p 837-856
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  • 28
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    Fluid motions in a low-G environment (1974)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: The importance of natural convection and other fluid motions in low-g space processing is now well recognized. Recent space experiments in the areas of natural convection and material processing, as well as results of theoretical studies, have yielded much needed information on fluid behavior in low-g environments. The state of knowledge of fluid motions in low-g environments is reviewed and the dimensional analysis approach used to assess the relative importances of various driving forces for fluid flow in four of the Skylab material processing experiments outlined. Results of dimensional analyses for the Skylab experiments, subsequently confirmed by actual space data, are presented. Finally, the limits of dimensional analysis in assessment studies are indicated.
    Keywords: FLUID MECHANICS
    Type: NASA. Marshall Space Flight Center Proc. of the 3d Space Processing Symp. on Skylab Results, Vol. 2; p 691-727
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  • 29
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    Experiments on confined turbulent jets in cross flow (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Results are reported of experiments on the effects of an opposite wall on the characteristics of turbulent jets injected into a cross flow, for unheated and heated jets. Longitudinal and transverse distributions of velocity and temperature are presented for single and multiple circular jets, and trajectories are presented for two-dimensional jets. The opposite wall has relatively little effect on a single jet unless the ratio of jet to cross flow momentum flux is large enough for the jet to impinge on the opposite wall. For a row of jets aligned perpendicularly to the cross flow, the opposite wall exerts progressively larger influence as the spacing between jets decreases. Much of the effect of jet and wall proximity can be understood by considering the interaction of the vortex flow which is the major feature of the structure of a single jet in a cross flow. Smoke photographs are shown to elucidate some of the interaction patterns.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2392
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  • 30
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    Decay of far flow field in trailing vortices (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A finite difference machine code is used in the wake vortex problems in the quasi-cylindrical boundary layer approximation. A turbulent energy model containing new features is developed that accounts for the major effects disclosed by more advanced models in which the parameters are not yet established. Several puzzles that arose in previous theoretical investigations of wake vortices are resolved.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7568 , A-5181
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  • 31
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    Effect of throttling on interface behavior and liquid residuals in weightlessness (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An experimental investigation was conducted to study liquid-vapor interface behavior and subsequent vapor ingestion in a flat-bottomed cylindrical tank following a single-step throttling in outflow rate in a weightless environment. A throttling process in which the final Weber number was one-tenth of the initial Weber number tended to excite large-amplitude symmetric slosh, with the amplitude generally increasing as initial Weber number increased. As expected, liquid residuals were lower than those obtained without throttling and, for moderate values of initial Weber number, could be adequately predicted by assuming that all draining took place at the final Weber number. At large values of Weber number, residuals tended to be lower than this predicted value.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-3034 , E-7833
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  • 32
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    Comparison of measured and calculated velocity profiles of a laminar incompressible free jet at low Reynolds numbers (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A comparison of the measured and calculated velocity profiles of a laminar, incompressible, low Reynolds number jet is presented. The experimental jet was produced by a nozzle which consists of a porous metal plate covering the end of a pipe. This nozzle produces a uniform exit velocity profile at Reynolds numbers well below those at which conventional contoured nozzles are completely filled by the boundary layer. A jet mixing analysis based on the boundary-layer equations accurately predicted the velocity field for each test condition. The Reynolds number based on nozzle diameter ranged from 50 to 1000 with jet exit velocity either 30 or 61 m/s (100 or 200 ft/sec).
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7510 , L-9277
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  • 33
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    An experimental investigation of wall boundary layer transition Reynolds numbers in an expansion tube (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Experimental measurements of boundary-layer transition in an expansion-tube test-gas flow are presented along with radial distributions of pitot pressure. An integral method for calculating constant Reynolds number lines for an expansion-tube flow is introduced. Comparison of experimental data and constant Reynolds number calculations has shown that for given conditions, wall boundary-layer transition occurs at a constant Reynolds number in an expansion-tube flow. Operating conditions in the expansion tube were chosen so that the effects of test-gas nonequilibrium on boundary-layer transition could be studied.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7541 , L-9337
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    The application of Riegels' rule and time-like damping to transonic flow calculations (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Finite difference relaxation solutions of the nonlinear small perturbation equations have proven reliable and successful in determining the transonic flowfields about thin airfoils. However, application of the small perturbation approach to thick airfoils usually results in an accuracy less than desirable. The incorporation of Riegels' Rule and time-like damping into the small perturbation approach and their application to thick and thin airfoils in transonic flow are discussed. Studies for thick and thin airfoils are presented. It is concluded that Riegels' Rule and damping should both be included in small perturbation transonic flow calculations.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138181 , TAMRF-3033-7401 , AIAA Southwestern Student Paper Competition; Arlington, TX; United States
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  • 35
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    A weak interaction study of the viscous flow about oscillating airfoils (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An incompressible inviscid and a viscous flow calculation procedure is developed by assuming the viscous correction to the inviscid flow pressure distribution is small (weak interaction) to predict the flow about airfoils oscillating in pitch and heave. The calculations made in the investigation predict the detailed viscous flow regions including transition and separation phenomena and provide a detailed analysis of leading edge separation, transition, and reattachment. Results from the calculation show the leading edge viscous flow field to be quasi-steady although the imposed inviscid pressure distribution shows significant unsteady effects. Although unable to predict the flow field about a stalled airfoil, the indications are that the present procedure can indicate the onset of catastrophic flow separation.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-132425
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  • 36
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    Topics in structural dynamics: Nonlinear unsteady transonic flows and Monte Carlo methods in acoustics (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results are reported of two unrelated studies. The first was an investigation of the formulation of the equations for non-uniform unsteady flows, by perturbation of an irrotational flow to obtain the linear Green's equation. The resulting integral equation was found to contain a kernel which could be expressed as the solution of the adjoint flow equation, a linear equation for small perturbations, but with non-constant coefficients determined by the steady flow conditions. It is believed that the non-uniform flow effects may prove important in transonic flutter, and that in such cases, the use of doublet type solutions of the wave equation would then prove to be erroneous. The second task covered an initial investigation into the use of the Monte Carlo method for solution of acoustical field problems. Computed results are given for a rectangular room problem, and for a problem involving a circular duct with a source located at the closed end.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138110 , ESS-4022-113-74
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  • 37
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    Drag and distribution measurements of single-element fuel injectors for supersonic combustors (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The drag caused by several vortex generating fuel injectors for scramjet combustors was measured in a Mach 2 to 3.5 airstream. Injector drag was found to be strongly dependent on injector thickness ratio. The distribution of helium injected into the stream was measured both in the near field and the far field of the injectors for a variety of pressure ratios. The far field results differed appreciably from measurements in the near field. Injection pressure ratio was found to profoundly influence the penetration. One of the aerowing configurations tested yielded low drag consistent with desirable penetration and spreading characteristics.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-3015 , E-7662
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  • 38
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    Numerical calculations of two dimensional, unsteady transonic flows with circulation (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The feasibility of obtaining two-dimensional, unsteady transonic aerodynamic data by numerically integrating the Euler equations is investigated. An explicit, third-order-accurate, noncentered, finite-difference scheme is used to compute unsteady flows about airfoils. Solutions for lifting and nonlifting airfoils are presented and compared with subsonic linear theory. The applicability and efficiency of the numerical indicial function method are outlined. Numerically computed subsonic and transonic oscillatory aerodynamic coefficients are presented and compared with those obtained from subsonic linear theory and transonic wind-tunnel data.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7605 , A-5265
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  • 39
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    Wind tunnel investigation of aerodynamic characteristics of a scale model of a D5 bulldozer and an M109 self-propelled 155 mm Howitzer (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Wind tunnel tests were conducted on a scale model of a D5 bulldozer and an M109 self-propelled 155 MM howitzer to determine the aerodynamic characteristics of these typical externally-suspended heavy lift helicopter cargo configurations. Tests were made over a large range of pitch and yaw attitudes at a nominal Reynolds number per unit length of 1.5 x 10 to the 6th power.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-62330
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  • 40
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    Nonlinear cellular motions in Poiseuille channel flow (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: In a number of nonlinear solutions to the equations of channel flow the velocity is decomposed into a mean part plus a nonlinear disturbance. The idea that nonlinear effects place a limitation on the amplitudes of the disturbance flow is considered. In the reported investigation the disturbance flow is represented by drastically limited Fourier expansions in the downstream coordinate. The resulting equations are solved numerically with high accuracy to obtain a good representation of the cross-stream structure of the solution. The results of the investigation show that indeed the nonlinear terms always limit the amplitude of the disturbance flow in this approximation.
    Keywords: FLUID MECHANICS
    Type: Journal of Fluid Mechanics; 64; June 19
    Format: text
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  • 41
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    Computer extension and analytic continuation of Stokes' expansion for gravity waves (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Stokes' infinitesimal-wave expansion for steady progressive free-surface waves has been extended to high order using a computer to perform the coefficient arithmetic. Stokes' expansion has been found to be incapable of yielding the highest wave for any value of the water depth since convergence is limited by a square-root branch-point some distance short of the maximum. By reformulating the problem using a different independent parameter, the highest waves are obtained correctly. Series summation and analytic continuation are facilitated by the use of Pade approximants. The method is valid in principle for any finite value of the wavelength and solutions of high accuracy can be obtained for most values of the wave height and water depth.
    Keywords: FLUID MECHANICS
    Type: AD-A000773 , AFOSR-74-1574TR , Journal of Fluid Mechanics; 62; Feb. 11
    Format: text
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  • 42
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    Boundary-layer transition and displacement thickness effects on zero-lift drag of a series of power-law bodies at Mach 6 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Wave and skin-friction drag have been numerically calculated for a series of power-law bodies at a Mach number of 6 and Reynolds numbers, based on body length, from 1.5 million to 9.5 million. Pressure distributions were computed on the nose by the inverse method and on the body by the method of characteristics. These pressure distributions and the measured locations of boundary-layer transition were used in a nonsimilar-boundary-layer program to determine viscous effects. A coupled iterative approach between the boundary-layer and pressure-distribution programs was used to account for boundary-layer displacement-thickness effects. The calculated-drag coefficients compared well with previously obtained experimental data.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7723 , L-9646
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  • 43
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    Turbulent transport of heat and momentum in a boundary layer subject to deceleration, suction and variable wall temperature (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The relationship between the turbulent transport of heat and momentum in an adverse pressure gradient boundary layer was studied. An experimental study was conducted of turbulent boundary layers subject to strong adverse pressure gradients with suction. Near-equilibrium flows were attained, evidenced by outer-region similarity in terms of defect temperature and defect velocity profiles. The relationship between Stanton number and enthalpy thickness was shown to be the same as for a flat plate flow both for constant wall temperature boundary conditions and for steps in wall temperature. The superposition principle used with the step-wall-temperature experimental result was shown to accurately predict the Stanton number variation for two cases of arbitrarily varying wall temperature. The Reynolds stress tensor components were measured for strong adverse pressure gradient conditions and different suction rates. Two peaks of turbulence intensity were found: one in the inner and one in the outer regions. The outer peak is shown to be displaced outward by an adverse pressure gradient and suppressed by suction.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139655 , SU-HMT-17
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  • 44
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    Investigation of an anomalous flow condition of the Langley pilot model expansion tube (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Free-stream flow velocity measurements were made in the Langley pilot model expansion tube during the test flow interval. During this interval, an anomalous dip in pitot pressure occurs for the expansion tube operating conditions employed. Within the test flow interval, the main conclusions reached from comparison of the measured flow velocity, pitot pressure, and tube wall pressure are: the variations which occur in velocity and wall pressure are small compared with the variations in pitot pressure; a corresponding dip in the derived flow density is associated with the dip in pitot pressure; and the value of the average density over the interval, which results from the expansion from the shocked intermediate chamber condition, is approximately one-half of the value that can result from only an isentropic process.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7704 , L-9633
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  • 45
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    Boundary layer integral matrix procedure code modifications and verifications (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A summary of modifications to Aerotherm's Boundary Layer Integral Matrix Procedure (BLIMP) code is presented. These modifications represent a preliminary effort to make BLIMP compatible with other JANNAF codes and to adjust the code for specific application to rocket nozzle flows. Results of the initial verification of the code for prediction of rocket nozzle type flows are discussed. For those cases in which measured free stream flow conditions were used as input to the code, the boundary layer predictions and measurements are in excellent agreement. In two cases, with free stream flow conditions calculated by another JANNAF code (TDK) for use as input to BLIMP, the predictions and the data were in fair agreement for one case and in poor agreement for the other case. The poor agreement is believed to result from failure of the turbulent model in BLIMP to account for laminarization of a turbulent flow. Recommendations for further code modifications and improvements are also presented.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-120364 , AEROTHERM-74-95
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  • 46
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    Comparison of interference-free numerical results with sample experimental data for the AEDC wall-interference model at transonic and subsonic flow conditions (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Numerical results obtained from two computer programs recently developed with NASA support and now available for use by others are compared with some sample experimental data taken on a rectangular-wing configuration in the AEDC 16-Foot Transonic Tunnel at transonic and subsonic flow conditions. This data was used in an AEDC investigation as reference data to deduce the tunnel-wall interference effects for corresponding data taken in a smaller tunnel. The comparisons were originally intended to see how well a current state-of-the-art transonic flow calculation for a simple 3-D wing agreed with data which was felt by experimentalists to be relatively interference-free. As a result of the discrepancies between the experimental data and computational results at the quoted angle of attack, it was then deduced from an approximate stress analysis that the sting had deflected appreciably. Thus, the comparisons themselves are not so meaningful, since the calculations must be repeated at the proper angle of attack. Of more importance, however, is a demonstration of the utility of currently available computational tools in the analysis and correlation of transonic experimental data.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-71991
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    An experimental investigation of the flow field for double-wedge configurations in a Mach 4.97 stream (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The viscous-inviscid interactions which perturb the flow around the wing leading edge are discussed. The flow field perturbation results when the fuselage-generated shock wave interacts with the wing-generated shock wave. Three types of shock interference patterns are possible for the wing leading edge of the orbiter.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134386 , REPT-74003
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  • 48
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    Quantized vortices around wavefront nodes, 2 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Quantized vortices can occur around nodal points in wavefunctions. The derivation depends only on the wavefunction being single valued, continuous, and having continuous first derivatives. Since the derivation does not depend upon the dynamical equations, the quantized vortices are expected to occur for many types of waves such as electromagnetic and acoustic. Such vortices have appeared in the calculations of the H + H2 molecular collisions and play a role in the chemical kinetics. In a companion paper, it is shown that quantized vortices occur when optical waves are internally reflected from the face of a prism or particle beams are reflected from potential energy barriers.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139530 , WIS-TCI-515
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  • 49
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    An experimental and theoretical study of the flow phenomena within a vortex sink rate sensor (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tests were conducted to obtain a description of the flow field within a vortex sink rate sensor and to observe the influence of viscous effects on its performance. The characteristics of the sensor are described. The method for conducting the test is reported. It was determined that for a specific mass flow rate and the geometry of the vortex chamber, the flow in the vortex chamber was only affected, locally, by the size of the sink tube diameter. Within the sink tube, all three velocity components were found to be higher for the small sink tube diameters. As the speed of rotation of the sensor was increased, the tangential velocities within the vortex chamber, as well as in the sink tube, increased in proportion to the speed of rotation.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139648 , TR-74-T2
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  • 50
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    Improvements to embedded shock wave calculations for transonic flow-applications to wave drag and pressure rise predictions (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The numerical solution of a single, mixed, nonlinear equation with prescribed boundary data is discussed. A second order numerical procedure for solving the nonlinear equation and a shock fitting scheme was developed to treat the discontinuities that appear in the solution.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139487
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    The use of digital techniques to examine the intermittent region of a turbulent jet (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Voltage signals, sampled at a high rate in the intermittent region of a round jet, are analyzed to provide instantaneous velocity vector information and measures of the vorticity and dissipation scales. A clustering routine to assess the feasibility of using the voltage readings to define the vortical, nonvortical state of the flow is also utilized. The results indicate that the clustering routine is partially successful; more sophisticated discrimination techniques will be required for a complete specification.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139396
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  • 52
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    Transonic conical flow (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The problem of inviscid, steady transonic conical flow, formulated in terms of the small disturbance theory, is studied. The small disturbance equation and similarity rules are presented, and a boundary value problem is formulated for the case of a supersonic freestream Mach number. The equation for the perturbation potential is solved numerically using an elliptic finite difference system. The difference equations are solved with a point relaxation algorithm that is also capable of capturing the shock wave during the iteration procedure by using the boundary conditions at the shock. Numerical calculations, for shock location, pressure distribution and drag coefficient, are presented for a family of nonlifting conical wings. The theory of slender wings is also presented and analytical results for pressure and drag coefficients are obtained.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139564 , UCLA-ENG-7382
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  • 53
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    A modified Newton-Raphson analysis of flight measurements of the trailing vortices of a heavy jet transport (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A modified Newton-Raphson method has been used to determine the parameters in equations describing the vortex flow to obtain a best match with flight measurements of the flow behind the C-5A airplane. The flight measurements were made using a specially instrumented T-33 airplane which passed as closely as possible to the centers of the trailing vortices at several distances behind the C-5A airplane. The flight measurements were transformed to flow velocity relative to an inertial frame of reference. The assumed form of the flow consisted of the superposition of two counterrotating, finite core vortices. The positions of the vortex centers, their total circulation, the effective eddy viscosity and measurement bias were the parameters adjusted. The assumed form of vortex flow fit well the measured velocities for the numerous sets of data, both flaps up and down for the C-5A airplane. The resulting values of total circulation, however, were about two-thirds that expected of a wing with an elliptical loading. A partial explanation of the less than expected circulation is a dip in the spanwise lift distribution at the airplane's center line. The distance between the trailing vortices at the smallest times encountered is somewhat less than that expected for an elliptical wing loading.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7404 , L-8838
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    Analysis of sound propagation in ducts using the wave envelope concept (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A finite difference formulation is presented for sound propagation in a rectangular two-dimensional duct without steady flow for plane wave input. Before the difference equations are formulated, the governing Helmholtz equation is first transformed to a form whose solution does not oscillate along the length of the duct. This transformation reduces the required number of grid points by an order of magnitude, and the number of grid points becomes independent of the sound frequency. Physically, the transformed pressure represents the amplitude of the conventional sound wave. Example solutions are presented for sound propagation in a one-dimensional straight hard-wall duct and in a two-dimensional straight soft-wall duct without steady flow. The numerical solutions show evidence of the existence along the duct wall of a developing acoustic pressure diffusion boundary layer which is similar in nature to the conventional viscous flow boundary layer. In order to better illustrate this concept, the wave equation and boundary conditions are written such that the frequency no longer appears explicitly in them. The frequency effects in duct propagation can be visualized solely as an expansion and stretching of the suppressor duct.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7719 , E-7941
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    Calculation of turbulent shear stress in supersonic boundary layer flows (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis of turbulent boundary layer flow characteristics and the computational procedure used are discussed. The integrated mass and momentum flux profiles and differentials of the integral quantities are used in the computations so that local evaluation of the streamwise velocity gradient is not necessary. The computed results are compared with measured shear stress data obtained by using hot wire anemometer and laser velocimeter techniques. The flow measurements were made upstream and downstream of an adiabatic unseparated interaction of an oblique shock wave with the turbulent boundary layer on the flat wall of a two dimensional wind tunnel. A comparison of the numerical analysis and actual measurements is made and the effects of small differences in mean flow profiles on the computed shear stress distributions are discussed.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138302
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  • 56
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    Shock-induced separation of adiabatic turbulent boundary layers in supersonic axially symmetric internal flow (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation at Mach 4 of shock-induced turbulent boundary layer separation at the walls of axially symmetric flow passages is discussed, with particular emphasis placed on determining the shock strengths required for incipient separation. The shock waves were produced by interchangeable sting-mounted cones placed on the axes of the flow passages and aligned with the freestream flow. The interactions under study simulate those encountered in axially symmetric engine inlets of supersonic aircraft. Knowledges of the shock strengths required for boundary layer separation in inlets is important since for shocks of somewhat greater strength rather drastic alterations in the inlet flow field may occur.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138303
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  • 57
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    Mean and fluctuating flow measurements in axisymmetric supersonic boundary layer flow subjected to distributed adverse pressure gradients (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Measurements have been made of the mean flow properties and turbulent fluctuations in adiabatic turbulent boundary layer flows subjected to distributed adverse pressure gradients. In the freestream region upstream of the adverse pressure gradient the Mach number was 3.86, the unit Reynolds number 5.3 million per foot. The boundary layer developed on the wall of an axisymmetric nozzle and straight test section. In order to avoid the effects of streamwise surface curvature the adverse pressure gradients at the test section wall were induced by contoured centerbodies mounted on the wind tunnel centerline. The flow under study simulated that which might be found in an axially symmetric engine inlet of a supersonic aircraft.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-139435
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  • 58
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    Combustion of hydrogen-air jets in local chemical equilibrium: A guide to the CHARNAL computer program (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A guide to a computer program, written in FORTRAN 4, for predicting the flow properties of turbulent mixing with combustion of a circular jet of hydrogen into a co-flowing stream of air is presented. The program, which is based upon the Imperial College group's PASSA series, solves differential equations for diffusion and dissipation of turbulent kinetic energy and also of the R.M.S. fluctuation of hydrogen concentration. The effective turbulent viscosity for use in the shear stress equation is computed. Chemical equilibrium is assumed throughout the flow.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2407 , REPT-73-1
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  • 59
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    Solutions of the Navier-Stokes equations for vortex breakdown (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Steady solutions of the Navier-Stokes equations, in terms of velocity and pressure, for breakdown in an unconfined viscous vortex are obtained numerically using the artificial compressibility technique of Chorin combined with an ADI finite-difference scheme. Axisymmetry is assumed and boundary conditions are carefully applied at the boundaries of a large finite region in an axial plane while resolution near the axis is maintained by a coordinate transformation. The solutions, which are obtained for Reynolds numbers up to 200 based on the free-stream axial velocity and a characteristic core radius, show that breakdown results from the diffusion and convection of vorticity away from the vortex core which, because of the strong coupling between the circumferential and axial velocity fields in strongly swirling flows, can lead to stagnation and reversal of the axial flow near the axis.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138901 , FM-74-6
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    Similitude requirements for hypersonic, rarefied, nonequilibrium flow (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Similitude requirements for hypersonic, rarefied flow with nonequilibrium chemistry and vibration are presented. The full Navier-Stokes equations with catalytic or noncatalytic walls and with or without slip conditions are nondimensionalized. The heat transfer coefficient is written in terms of fourteen dimensionless parameters and reduced to four by making the binary scaling assumption. Duplication of blunt and sharp nose heat transfer requires the use of air over a geometrically similar model with the same free stream velocity, wall temperature and product of free stream density and characteristic length. Estimates of this heat transfer coefficient are also presented.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-64859
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  • 61
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    Development of a method of analysis and computer program for calculating the inviscid flow about the windward surfaces of space shuttle configurations at large angles of attack (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A general method developed for the analysis of inviscid hypersonic shock layers is discussed for application to the case of the shuttle vehicle at high (65 deg) angle of attack. The associated extensive subsonic flow region caused convergence difficulties whose resolution is discussed. It is required that the solution be smoother than anticipated.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-132453 , MML-TR-74-5C
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    Effect of mean-velocity profile shapes on sound transmission through two-dimensional ducts (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Acoustic propagation through a lined two-dimensional duct is examined in order to assess the influence of the shape of the mean-velocity profile on the attenuation rate. Five mean-velocity profiles are considered: linear, parabolic, Pohlhausen, 1/7th power law with a linear sub-layer, and linear with slip at the wall. It is shown that when the attenuation rate is tabulated as a function of the boundary-layer thickness, as is usually done, substantially different results are obtained from the several mean profiles. However, when the displacement thickness is used, a considerable collapse is achieved in the attenuation curves that are obtained from the various profiles. For downstream propagation, all profiles produce essentially the same results over a reasonable range of boundary-layer thickness. However, for many cases of upstream propagation, the results from the 'turbulent' boundary-layer profiles differ significantly from the results of the other profiles even when compared on the basis of displacement thickness.
    Keywords: FLUID MECHANICS
    Type: Journal of Sound and Vibration; 34; June 8
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    Turbulent vortex streets and the entrainment mechanism of the turbulent wake (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The results of an experimental investigation of a turbulent vortex street in the range from 1000 to 20,000 are presented. The vortex street was created by the motion of a circular cylinder in a motionless fluid (mercury). Photographs obtained showed that the turbulent street, created by the vortex shedding behind the cylinder, persisted at longer downstream distances and higher Reynolds numbers than previously reported in the literature. A theory was developed to account for the experimental measurements pertaining to the change of the geometrical characteristics, (the distance between the two rows of vortices and the longitudinal distance between two consecutive vortices on the same row), of the street in the downstream direction. The implications of the structure of the vortex street on the entrainment mechanism of the turbulent wake are discussed.
    Keywords: FLUID MECHANICS
    Type: Journal of Fluid Mechanics; 62; Jan. 8
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  • 64
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    Cavitation in liquid cryogens. 4: Combined correlations for venturi, hydrofoil, ogives, and pumps (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of a series of experimental and analytical cavitation studies are presented. Cross-correlation is performed of the developed cavity data for a venturi, a hydrofoil and three scaled ogives. The new correlating parameter, MTWO, improves data correlation for these stationary bodies and for pumping equipment. Existing techniques for predicting the cavitating performance of pumping machinery were extended to include variations in flow coefficient, cavitation parameter, and equipment geometry. The new predictive formulations hold promise as a design tool and universal method for correlating pumping machinery performance. Application of these predictive formulas requires prescribed cavitation test data or an independent method of estimating the cavitation parameter for each pump. The latter would permit prediction of performance without testing; potential methods for evaluating the cavitation parameter prior to testing are suggested.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2448
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  • 65
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    Use of hexafluoroethane to simulate the inviscid real-gas effects on blunt entry vehicles (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results are presented of an experimental and theoretical investigation of the use of equilibrium hexafluoroethane C2F6 as an undissociated test gas in a wind tunnel to simulate the inviscid aerodynamic characteristics of blunt bodies in high-speed flight where dissociation occurs. The results indicate that the use of C2F6 as a test gas in wind tunnels is a practical and relatively simple and inexpensive method of obtaining test conditions with large normal-shock density ratios. Equations for the thermodynamic and transport properties of C2F6 are also included.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7701 , L-9459
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  • 66
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    Improved curve fits for the thermodynamic properties of equilibrium air suitable for numerical computation using time-dependent or shock-capturing methods, part 1 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Simplified curve fits for the thermodynamic properties of equilibrium air were devised for use in either the time-dependent or shock-capturing computational methods. For the time-dependent method, curve fits were developed for p = p(e, rho), a = a(e, rho), and T = T(e, rho). For the shock-capturing method, curve fits were developed for h = h(p, rho) and T = T(p, rho). The ranges of validity for these curves fits were for temperatures up to 25,000 K and densities from 10 to the minus 7th power to 10 to the 3d power amagats. These approximate curve fits are considered particularly useful when employed on advanced computers such as the Burroughs ILLIAC 4 or the CDC STAR.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2470
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  • 67
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    Measurement and correlation of aerodynamic heating to surface corrugation stiffened structures in thick turbulent boundary layers (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The flow conditions for which heating distributions were measured on corrugated surfaces and wavy walls in turbulent boundary layers are shown, along with the ratio of the displacement thickness to the roughness height versus the local edge Mach number for an equivalent smooth surface. The present data are seen to greatly extend the range of data available on corrugated surfaces in turbulent boundary layers. These data were obtained by testing fullscale corrugation roughened panels in the wall boundary layer of a supersonic and hypersonic wind tunnel. The experimental program used to obtain the data is described. The data are analyzed and correlated in terms of the pertinent flow and geometric parameters. The developed correlations are compared with the available thin boundary layer data, as well as with previously published correlation techniques.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-132503
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  • 68
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    On conditional sampling for turbulent flow studies (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The conditional sampling technique is analyzed as a weighted time average for turbulent flow. The various conditional averages are obtained by using different types of weighting functions. A second averaging relation is obtained between the conventional averages and the conditional averages. A few examples are given in which simplified expressions are used.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-64886
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  • 69
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    Analysis of dynamic stall using unsteady boundary-layer theory (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The unsteady turbulent boundary layer and potential flow about a pitching airfoil are analyzed using numerical methods to determine the effect of pitch rate on the delay in forward movement of the rear flow reversal point. An explicit finite difference scheme is used to integrate the unsteady boundary layer equations, which are coupled at each instant of time to a fully unsteady and nonlinear potential flow analysis. A substantial delay in forward movement of the reversal point is demonstrated with increasing pitch rate, and it is shown that the delay results partly from the alleviation of the gradients in the potential flow, and partly from the effects of unsteadiness in the boundary layer itself. The predicted delay in flow-reversal onset, and its variation with pitch rate, are shown to be in reasonable agreement with experimental data relating to the delay in dynamic stall. From the comparisons it can be concluded (a) that the effects of time-dependence are sufficient to explain the failure of the boundary layer to separate during the dynamic overshoot, and (b) that there may be some link between forward movement of the reversal point and dynamic stall.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2462
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  • 70
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    Improved solution for potential flow about arbitrary axisymmetric bodies by the use of a higher-order surface source method. Part 2. User's manual for computer program (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The surface-source method of calculating potential flow is improved by refining the underlying numerical analysis. The present analysis uses parabolic elements and linearly-varying source density which results in a large increase in computing speed and accuracy. The computer program including all relevant input and output is described.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134695 , MDC-J6627-02
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  • 71
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    Improved solution for potential flow about arbitrary axisymmetric bodies by the use of a higher-order surface source method. Part 1. Theory and results (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The surface-source method of calculating potential flow is improved by refining the underlying numerical analysis. The analysis uses parabolic elements and linearly-varying source density. The result is a large increase in computing speed and accuracy. The theory is described, and the effectiveness of the modification is illustrated.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134694 , MDC-J6627-01
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  • 72
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    The effects of forward speed on fan inlet turbulence and its relation to tone noise generation (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of forward speed on fan inlet turbulence was studied to determine the feasibility of using a wind tunnel to simulate various flight conditions where turbulence of atmospheric origin enters the engine inlet. The investigation was conducted in the Ames 7- by 10-foot Wind Tunnel with a small-scale low pressure-ratio fan. Results indicate that a wind tunnel of this size does produce large turbulence scale appropriate for simulation of atmospheric scale. But the tunnel's low turbulence intensity seems to cause results contrary to existing theories on the effects of fan inlet velocity ratio on turbulence scale. Limited results with artificially increased turbulence intensity removed this contradiction. Acoustic measurements showed the impact of inlet turbulence on fantone noise.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-62381
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  • 73
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    Two stage low noise advanced technology fan. 1: Aerodynamic, structural, and acoustic design (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A two-stage fan was designed to reduce noise 20 db below current requirements. The first-stage rotor has a design tip speed of 365.8 m/sec and a hub/tip ratio of 0.4. The fan was designed to deliver a pressure ratio of 1.9 with an adiabatic efficiency of 85.3 percent at a specific inlet corrected flow of 209.2kg/sec/sq m. Noise reduction devices include acoustically treated casing walls, a flowpath exit acoustic splitter, a translating centerbody sonic inlet device, widely spaced blade rows, and the proper ratio of blades and vanes. Multiple-circular-arc rotor airfoils, resettable stators, split outer casings, and capability to go to close blade-row spacing are also included.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134662 , PWA-5069
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  • 74
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    Unsteady Subsonic and Transonic Potential Flow over Helicopter Rotor Blades (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Differential equations and boundary conditions for a rotor blade in forward flight, with subsonic or transonic tip Mach number, are derived. A variety of limiting flow regimes determined by different limits involving blade thickness ratio, aspect ratio, advance ratio and maximum tip Mach number is discussed. The transonic problem is discussed in some detail, and in particular the conditions that make this problem quasi-steady or essentially unsteady are determined. Asymptotic forms of equations and boundary conditions that are valid in an appropriately scaled region of the tip and an azimuthal sector on the advancing side are derived. The equations are then put in a form that is valid from the blade tip inboard through the strip theory region.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2463 , REPT-74-2
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  • 75
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    Flow in a discrete slotted nozzle with massive injection (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An experimental investigation has been conducted to determine the effect of massive wall injection on the flow characteristics in a slotted nozzle. Some of the experiments were performed on a water table with a slotted-nozzle test section. This has 45 deg and 15 deg half angles of convergence and divergence, respectively, throat radius of 2.5 inches, and throat width of 3 inches. The hydraulic analogy was employed to qualitatively extend the results to a compressible gas flow through the nozzle. Experimental results from the water table include contours of constant Froude and Mach number with and without injection. Photographic results are also presented for the injection through slots of CO2 and Freon-12 into a main-stream air flow in a convergent-divergent nozzle in a wind tunnel. Schlieren photographs were used to visualize the flow, and qualititative agreement between the results from the gas tunnel and water table is good.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134505
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    Linear viscous stability analysis of the stratified Bickley jet (1974)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The stability of the stably stratified Bickley jet to small disturbances in a viscous, heat conducting fluid is explored by numerical integration of the governing differential equation. Curves of neutral stability are presented in the alpha-R plane and the parametric dependence of these curves upon Richardson number and Prandtl number is examined. The results show a curious bimodal behavior of the curve of neutral stability for small Richardson numbers. In addition, closed neutral curves are found for Richardson numbers in excess of the critical value for the inviscid flow. The unstable regions in the interior of these curves increase with decreasing Prandtl number. Energy balances are computed which show the relative magnitude of the Reynolds stress production, buoyancy dissipation, and viscous dissipation terms across the flow. As the thermal diffusivity becomes large compared with the kinematic viscosity, the buoyancy term is suppressed and the thermal stratification becomes irrelevant.
    Keywords: FLUID MECHANICS
    Type: Physics of Fluids; 17; May 1974
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  • 77
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    A study of forced flow separation in rocket nozzle (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The characteristics of flow profile in a rocket nozzle during the start transient were investigated as well as possibilities of reducing the side-load thrust by sticking trip wires in the nozzle. To simplify the geometry of flow configuration around the trip wire, it was assumed that the flow is passing through square steps instead of round wires. Since a purely analytic solution is not available, a series of semiempirical solutions was proposed.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-120422
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    An experimental and numerical study of wave motion and upstream influence in a stratified fluid (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A system consisting of two superimposed layers of liquid of different densities, with a thin transition layer at the interface, provides a good laboratory model of an ocean thermocline or of an atmospheric inversion layer. This research was to gain knowledge about the propagation of disturbances within these two geophysical systems. The technique used was to observe the propagation of internal waves and of upstream influence within the density-gradient region between the two layers of liquid. The disturbances created by the motion of a vertical flat plate, which was moved longitudinally through this region, were examined both experimentally and numerically. An upstream influence, which resulted from a balance of inertial and gravitational forces, was observed, and it was possible to predict the behavior of this influence with the numerical model. The prediction included a description of the propagation of the upstream influence to steadily increasing distances from the flat plate and the shapes and magnitudes of the velocity profiles.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7744 , G-7440
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  • 79
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    Vibrational relaxation in expanding N2 and air (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: New N2 vibrational temperature data, obtained in expanding N2 and air using the electron beam technique, are analyzed permitting the vibrational relaxation times to be determined as a function of temperature. In addition, the effects on N2 vibrational relaxation times of direct vibrational energy transfer between N2 and H2O, between N2 and O2, and between N2 and free electrons introduced from arc contaminants are analyzed. The vibrational relaxation times determined from the present measurements agree with those measured in the expanding flows of shock tunnels and impact tubes. These expanding data also agree with relaxation times observed in acoustical resonant cavities where alternating compressions and expansions take place. The relaxation times in expanding flows (vib-tran exchange process) are found to be approximately 50 times faster than those measured in the compressing flow of shock tubes (tran-vib exchange process). This evidence strongly supports the concept that one relaxation time distribution cannot be applied to both exchange processes.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-71988
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  • 80
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    Interference heating from interactions of shock waves with turbulent boundary layers at Mach 6 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation of interference heating resulting from interactions of shock waves and turbulent boundary layers was conducted. Pressure and heat-transfer distributions were measured on a flat plate in the free stream and on the wall of the test section of the Langley Mach 6 high Reynolds number tunnel for Reynolds numbers ranging from 2 million to 400 million. Various incident shock strengths were obtained by varying a wedge-shock generator angle (from 10 deg to 15 deg) and by placing a spherical-shock generator at different vertical positions above the instrumented flat plate and tunnel wall. The largest heating-rate amplification factors obtained for completely turbulent boundary layers were 22.1 for the flat plate and 11.6 for the tunnel wall experiments. Maximum heating correlated with peak pressures using a power law with a 0.85 exponent. Measured pressure distributions were compared with those calculated using turbulent free-interaction pressure rise theories, and separation lengths were compared with values calculated by using different methods.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7649 , L-9458
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    Constant temperature hot wire anemometry data reduction procedure (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The theory and data reduction procedure for constant temperature hot wire anemometry are presented. The procedure is valid for all Mach and Prandtl numbers, but limited to Reynolds numbers based on wire diameter between 0.1 and 300. The fluids are limited to gases which approximate ideal gas behavior. Losses due to radiation, free convection and conduction are included.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138899 , FM-74-1
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  • 82
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    Tables and charts of equilibrium normal shock and shock tube solutions for pure CO2 with velocities to 16 km/second (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Equilibrium thermodynamic and flow properties are presented in tabulated and graphical form for moving, standing, and reflected normal shock waves in pure CO2, representative of Mars and Venus atmospheres. Properties include pressure, temperature, density, enthalpy, speed of sound, entropy, molecular weight ratio, isentropic exponent, velocity and species mole fractions. Incident (moving) shock velocities are varied from 1 to 16 km/sec for a range of initial pressure of 5 Newtons per square meter to 500 kilo Newtons per square meter. The present results are applicable to shock tube flows, and to free-flight conditions for a blunt body at high velocities. Working charts illustrating idealized shock-tube performance with CO2 test gas and heated helium and hydrogen driver gases are also presented.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-71982
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  • 83
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    Separated flow over bodies of revolution using an unsteady discrete-vorticity cross wake. Part 1: Theory and application (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method is developed to determine the flow field of a body of revolution in separated flow. The technique employed is the use of the computer to integrate various solutions and solution properties of the sub-flow fields which made up the entire flow field without resorting to a finite difference solution to the complete Navier-Stokes equations. The technique entails the use of the unsteady cross flow analogy and a new solution to the required two-dimensional unsteady separated flow problem based upon an unsteady, discrete-vorticity wake. Data for the forces and moments on aerodynamic bodies at low speeds and high angle of attack (outside the range of linear inviscid theories) such that the flow is substantially separated are produced which compare well with experimental data. In addition, three dimensional steady separation regions and wake vortex patterns are determined.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2414
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    Aerodynamic drag and fuel spreading measurements in a simulated scramjet combustion module (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The drag of a simulated scramjet combustion module was measured at Mach 2, 2.5, and 3. The combustor was rectangular in cross section and incorporated six swept fuel injector struts. The effect of strut leading edge radius, position of maximum thickness, thickness ratio, sweep angle, and strut length on the drag was determined. Reduction in thickness ratio had the largest effect on drag reduction. Sweeping the struts upstream yielded the same drag as sweeping the struts downstream and potentially offers the advantages of increased mixing time for the fuel. Helium injection was used to simulate hydrogen fuel. The interstrut spacing required to achieve good distribution of fuel was was found to be about 10 jet diameters. The contribution of helium injection to drag reduction was small.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7674 , E-7849
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  • 85
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    Discrete wall jets in quiescent air (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An experimental investigation was made of turbulent jet flows resulting from small, round nozzles discharging parallel to a smooth, flat wall in quiescent air. Nozzle axes were located 3.0 nozzle diameters above the wall surface. The case of a single nozzle and the case of a spanwise array of equally spaced nozzles were investigated. Several forms of approximate velocity profile similarity were noted, and the flow from the array of nozzles was seen to approach the form of a two-dimensional wall jet.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2388
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  • 86
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    Reacting viscous-shock-layer solutions with multicomponent diffusion and mass injection (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Numerical solutions of the viscous-shock-layer equation where the chemistry is treated as being either frozen, equilibrium, or nonequilibrium are presented. Also the effects of the diffusion model, surface catalysis, and mass injection on surface transport and flow parameters are considered. The flow is treated as a mixture of five inert and thermally perfect species. The viscous-shock-layer equations are solved by using an implicit-difference scheme. All calculations are for hyperboloids with included angles of 20 and 45. The flight conditions are those for various altitudes and velocities in the earth's atmosphere. Data are presented to show the effects of the chemical models; diffusion models; surface catalysis; and mass injection of air on heat transfer; skin friction; shock standoff distance; wall pressure distribution; and tangential velocity, temperature, and species profiles. The results show that an equilibrium analysis can substantially overpredict the heat-transfer rates for flow conditions experienced by earth-orbital entry vehicles. Moreover, at such conditions surface catalysis significantly influences heat-transfer and flow-field properties. If a binary rather than a multicomponent diffusion model is assumed, negligible errors in most flow properties result. Quantitative results are presented that show the effect of mass injection on flow properties within and downstream of the injection region.
    Keywords: FLUID MECHANICS
    Type: NASA-TR-R-411 , L-8861
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    Evaluation of analytical procedures for prediction of turbulent boundary layers on a porous wall (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical study has been made to determine how well current boundary layer prediction techniques work when there is mass transfer normal to the wall. The data that were considered in this investigation were for two-dimensional, incompressible, turbulent boundary layers with suction and blowing. Some of the bleed data were taken in an adverse pressure gradient. An integral prediction method was used three different porous wall skin friction relations, in addition to a solid-surface relation for the suction cases. A numerical prediction method was also used. Comparisons were made between theoretical and experimental skin friction coefficients, displacement and momentum thicknesses, and velocity profiles. The integral method with one of the porous wall skin friction laws gave very good agreement with data for most of the cases considered. The use of the solid-surface skin friction law caused the integral to overpredict the effectiveness of the bleed. The numerical techniques also worked well for most of the cases.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-3063 , E-7635
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  • 88
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    Model wall and recovery temperature effects on experimental heat transfer data analysis (1974)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Basic analytical procedures are used to illustrate, both qualitatively and quantitatively, the relative impact upon heat transfer data analysis of certain factors which may affect the accuracy of experimental heat transfer data. Inaccurate knowledge of adiabatic wall conditions results in a corresponding inaccuracy in the measured heat transfer coefficient. The magnitude of the resulting error is extreme for data obtained at wall temperatures approaching the adiabatic condition. High model wall temperatures and wall temperature gradients affect the level and distribution of heat transfer to an experimental model. The significance of each of these factors is examined and its impact upon heat transfer data analysis is assessed.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-71967
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  • 89
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    Use of multiple discrete wall jets for delaying boundary layer separation (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effectiveness of a spanwise array of small discrete blowing nozzles in preventing separation of a turbulent boundary layer was investigated experimentally. The spacing, axial location, and momentum flux of the nozzles were varied in a systematic way, and overall performance was measured for each combination. Extensive mean velocity profiles were measured for one selected combination. Overall diffusion achieved before separation was correlated successfully with a momentum flux excess parameter, and in terms of this parameter discrete nozzles, when advantageously placed, were found to perform somewhat better than an optimally placed two-dimensional jet slot.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-2389
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  • 90
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    Relaxation of an unsteady turbulent boundary layer on a flat plate in an expansion tube (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analysis is presented for the relaxation of a turbulent boundary layer on a semi-infinite flat plate after passage of a shock wave and a trailing driver gas-driven gas interface. The problem has special application to expansion-tube flows. The flow-governing equations have been transformed into the Crocco variables, and a time-similar solution is presented in terms of the dimensionless distance-time variable alpha and the dimensionless velocity variable beta. An eddy-viscosity model, similar to that of time-steady boundary layers, is applied to the inner and outer regions of the boundary layer. A turbulent Prandtl number equal to the molecular Prandtl number is used to relate the turbulent heat flux to the eddy viscosity. The numerical results, obtained by using the Gauss-Seidel line-relaxation method, indicate that a fully turbulent boundary layer relaxes faster to the final steady-state values of heat transfer and skin friction than a laminar boundary layer. The results also give a fairly good estimate of the local skin friction and heat transfer for near steady-flow conditions.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7499 , L-9168
    Format: application/pdf
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  • 91
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    Computer program for calculating laminar, transitional, and turbulent boundary layers for a compressible axisymmetric flow (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A finite-difference program is described for calculating the viscous compressible boundary layer flow over either planar or axisymmetric surfaces. The flow may be initially laminar and progress through a transitional zone to fully turbulent flow, or it may remain laminar, depending on the imposed boundary conditions, laws of viscosity, and numerical solution of the momentum and energy equations. The flow may also be forced into a turbulent flow at a chosen spot by the data input. The input may contain the factors of arbitrary Reynolds number, free-stream Mach number, free-stream turbulence, wall heating or cooling, longitudinal wall curvature, wall suction or blowing, and wall roughness. The solution may start from an initial Falkner-Skan similarity profile, an approximate equilibrium turbulent profile, or an initial arbitrary input profile.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7521 , E-7819
    Format: application/pdf
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  • 92
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    Measurements in a large angle oblique jet impingement flow (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Velocity and surface pressure measurements, in the flow field of an obliquely impinging jet, and their interpretation as regards the governing mechanics and the aerodynamic noise generation characteristics of such a flow are reported. A computer controlled probe positioning mechanism allowed the measurement of the velocity magnitude and direction in the plane parallel to the plate. The mean velocity and Reynolds stress components were recorded. Measures of the terms in the momentum equation reveal the character of the pressure gradients in the neighborhood of the stagnation point. The effects of the stagnation streamline location on the vorticity field and the vortex sound considerations are discussed in relationship to the aerodynamic noise generation effects of this flow.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138467
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  • 93
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    The effect of exit conditions on the development of an axisymmetric turbulent free jet (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The mean flow in the near field of a submerged axisymmetric jet emitting from a plane wall is presented. An experimental configuration to provide a nearly uniform mean velocity profile with a core of homogeneous turbulence of variable intensity and scale was developed. Eight cases with intensity values of 0.004 less than or equal to U prime less than or equal to 0.035 and integral scales up to l sub x/R = 0.28 were investigated using conditional sampling techniques. It was found that the jet exhibits an increasing momentum flux in the near field. Contrary to expectation and the accepted assumption of ambient static pressure in a turbulent jet, results seem to be conclusive and borne out by comparison with published data. Both integral measures, mass and momentum flux ratios, are insensitive to exit turbulence variations, but, the detailed structure (including centerline velocity) variations with exit conditions are systematic and explainable.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138468
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  • 94
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    ASTP fluid transfer measurement experiment (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The ASTP fluid transfer measurement experiment flight system design concept was verified by the demonstration and test of a breadboard model. In addition to the breadboard effort, a conceptual design of the corresponding flight system was generated and a full scale mockup fabricated. A preliminary CEI specification for the flight system was also prepared.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-134275 , DOC-74SD4215
    Format: application/pdf
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  • 95
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    Venting characteristics of gaseous helium and nitrogen discharging into a free stream at Mach numbers from 0.60 to 1.57 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation was conducted in the Lewis Research Center 8- by 6-Foot Supersonic Wind Tunnel to compare the effects on discharge coefficient of venting gaseous helium and gaseous nitrogen into a free stream. The test was conducted from Mach 0.06 to 1.57 with the vent mounted in a flat plate. The plate was strut mounted to the tunnel ceiling and at a 0 angle of attack. The gases were discharged from a plenum chamber through a 2.54-centimeter (1.00-in.) diameter vent. The ratio of local static pressure to plenum pressure was varied from 0.51 to 0.975. The ratio of boundary layer thickness to vent diameter varied from a maximum of 1.34 at Mach 0.60 to a minimum of 0.55 at Mach 1.37.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-2995 , E-7698
    Format: application/pdf
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  • 96
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    A review of turbulence measurements in compressible flow (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A survey of turbulence measurements in compressible flows is presented. The majority of turbulence measurements at super- and hypersonic speeds were made for the zero pressure gradient, turbulent boundary layer. It was found that the nondimensional turbulent stress terms for the zero pressure gradient flow appear to agree closely with equivalent incompressible measurements in the outer part of the boundary layer. The stress terms were nondimensionalized by the wall value of shear stress and plotted versus the distance from the wall, nondimensionalized by the boundary-layer thickness. Indirect evaluation of the total shear stress distribution from mean velocity measurements for both super- and hypersonic flows (zero pressure gradient, two-dimensional flows) indicate a near universal distribution. These total shear stress curves also agree very closely with measured incompressible shear stress distributions. Recent laser anemometer measurements of the turbulent Reynolds shear stress (puv), reported by Johnson and Rose for a Mach number 2.9 flow, are in reasonable agreement with the expected total shear stress curve over the outer 60% of the boundary layer.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-62337
    Format: application/pdf
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  • 97
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    Experimental study of sharp and blunt nose streamwise corners at Mach 20 (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Extensive heat transfer and pressure distribution data and oil flow studies on sharp and blunt-nose streamwise corners at Mach 20 in helium are presented. The far corner boundary layers on the wedge surfaces forming the corners are laminar for most test conditions. Analysis of the data indicates that the corner flow field geometry can be described in terms of the inviscid shock pattern on the two dimensional surfaces forming the corner. Parameters used to correlate blunt shock growth can be used to correlate features of the flow field observed in oil flow photographs in addition to the measured pressure and heat transfer distributions on the models. The flow field structure is described from available experimental data. Regions of the flow in which the structure still is not known are discussed.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7398 , L-8830
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  • 98
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    Differential analysis for the turbulent boundary layer on a compressor blade element (including boundary-layer separation) (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A two-dimensional differential analysis is developed to approximate the turbulent boundary layer on a compressor blade element with strong adverse pressure gradients, including the separated region with reverse flow. The predicted turbulent boundary layer thicknesses and velocity profiles are in good agreement with experimental data for a cascade blade, even in the separated region.
    Keywords: FLUID MECHANICS
    Type: NASA-TN-D-7635 , E-7506
    Format: application/pdf
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  • 99
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    Comparison of theoretical and experimental boundary-layer development in a Mach 2.5 mixed-compression inlet (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical investigation was made of the boundary layer flow in an axisymmetric Mach 2.5 mixed compression inlet, and the results were compared with experimental measurements. The inlet tests were conducted in the Lewis 10- by 10-foot supersonic wind tunnel at a unit Reynolds number of 8.2 million/m. The inlet incorporated porous bleed regions for boundary layer control, and the effect of this bleed was taken into account in the analysis. The experimental boundary layer data were analyzed by using similarity laws from which the skin friction coefficient was obtained. The boundary layer analysis included predictions of laminar and turbulent boundary layer growth, transition, and the effects of the shock boundary layer interactions. In addition, the surface static pressures were compared with those obtained from an inviscid characteristics program. The results of investigation showed that the analytical techniques gave satisfactory predictions of the boundary layer flow except in regions that were badly distorted by the terminal shock.
    Keywords: FLUID MECHANICS
    Type: NASA-TM-X-3026 , E-7586
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  • 100
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    Research on free and impinging jets for the development of STOL aircraft (1974)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of the exit plane conditions on the initial region of an axisymmetric jet was systematically investigated. An essentially top-hat mean velocity profile and a homogeneous turbulence structure were maintained at the exit plane for eight distinct scale and intensity conditions. Mass and momentum flux values are independent of the exit turbulence structure for the range investigated; however, a significant (approximately 25%) increase in the latter implies a pronounced static pressure decrement inside the jet. Details of the velocity profile and turbulence structure are influenced by the exit plane conditions. The three radial-axial components of the Reynolds stress tensor have been conditionally sampled and are analyzed to show the initial condition effects.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-138031
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