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  • Other Sources  (872)
  • FLUID MECHANICS AND HEAT TRANSFER  (600)
  • NONMETALLIC MATERIALS
  • 1980-1984  (867)
  • 1950-1954  (5)
  • 1982  (522)
  • 1980  (345)
  • 1954  (5)
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  • Other Sources  (872)
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  • 1980-1984  (867)
  • 1950-1954  (5)
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  • 1
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    Shuttle tile environments and loads (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The Shuttle tile ascent environments are discussed and the procedures used to convert these environments into tile loads are outlined. Testing which was performed to quantify or verify the loads are discussed, along with the load combination rationale which was used. The discussion of the ascent environment is limited to the transonic/supersonic portion of the mission since mechanical design loads occur during this time, and to specific regions of the vehicle, in particular those regions in which undensified critical (black) tiles are located.
    Keywords: NONMETALLIC MATERIALS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 111-125
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  • 2
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    Structural characteristics of the shuttle orbiter ceramic thermal protection system (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The thermal protection system (TPS) of the Space Shuttle Orbiter is described as well as the results of dynamic reponse studies conducted in support of the efforts to certify the TPS for flight. The ceramic Thermal Protection System consists of ceramic tiles bonded to felt pads which are in turn bonded to the Orbiter substructure to protect the aluminum substructure from the heat of reentry.
    Keywords: NONMETALLIC MATERIALS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 101-110
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  • 3
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    Full-coverage film cooling (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Transpiration cooling is treated and then full coverage discrete hole injection for three injection orientations. Spacings with pitch to diameter ratios of 5 and 10 are discussed. The array is staggered, with the transverse pitch and the streamwise pitch the same. Results are presented in terms of the Stanton number using the heat transfer coefficient defined in terms of the difference between the wall temperature and the free stream temperature. Two values of Stanton number are provided for each situation: one with the injectant at wall temperature, and the other with the injectant at free stream temperature. These two values are equivalent to knowing the heat transfer coefficient and the adiabatic effectiveness. The heat transfer coefficient thus defined is used with the actual wall temperature to and the actual gas temperature to calculate the heat load. The principle of superposition thus invoked is valid exactly when the governing equations are linear.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 27 p
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  • 4
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    Fibrous ceramic insulation (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Some of the reusable heat shielding materials used to protect the Space Shuttles, their manufacturing processes, properties, and applications are discussed. Emphases is upon ceramic materials. Space Shuttle Orbiter tiles are discussed.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 261-274
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  • 5
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    Polymer research at NASA Langley Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.
    Keywords: NONMETALLIC MATERIALS
    Type: Advan. Mater. Technol.; p 29-48
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  • 6
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    Polymer materials research at NASA Ames Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: Polymers that provide significant improvements in both efficiency and safety for civilian transport aircraft and military combat aircraft were developed. High strength to weight structures such as carbon fiber composites with long term durability are requirements common to both classes of aircraft. Aircraft safety improvements in fire resistance and crashworthiness of primary and secondary structures are long term objectives for transport aircraft. Void filler ballistic foams, intumescent coatings, and radiation-resistant transparent plastics contribute to vulnerability reduction in combat military aircraft. Low and high velocity impact tolerance, fire resistance, thermal stability, and long term durability of polymers and components are emphasized.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 49-64
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  • 7
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    Synthesis of aminosilane and aromatic diamine intermediates for polymerization (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The preparation of monomers for use in a study to improve properties of epoxy polymers and silicone elastomers is described. Various approaches to the solution of the synthesis of aminosilane and diamine curing agents were examined. Ortho-, meta-, and para-substituted diamines where X is CH2, C(CH3)2, O, S, NH, or SO2 and n = 0, 1, 2, and 3 were investigated.
    Keywords: NONMETALLIC MATERIALS
    Type: The 1981 NASA(ASEE Summer Fac. Fellowship Program; 9 p
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  • 8
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    Development of high strength, high temperature ceramics (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 11 p
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  • 9
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    Heat loss and drag of spherical drop tube samples (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: the 1981 NASA(ASEE Summer Fac. Fellowship Program; 31 p
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  • 10
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    Development of toughened epoxy polymers for high performance composite and ablative applications (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A survey of current procedures for the assessment of state of cure in epoxy polymers and for the evaluation of polymer toughness as related to nature of the crosslinking agent was made to facilitate a cause-effect study of the chemical modification of epoxy polymers. Various conformations of sample morphology were examined to identify testing variables and to establish optimum conditions for the selected physical test methods. Dynamic viscoelasticity testing was examined in conjunction with chemical analyses to allow observation of the extent of the curing reaction with size of the crosslinking agent the primary variable. Specifically the aims of the project were twofold: (1) to consider the experimental variables associated with development of "extent of cure" analysis, and (2) to assess methodology of fracture energy determination and to prescribe a meaningful and reproducible procedure. The following is separated into two categories for ease of presentation.
    Keywords: NONMETALLIC MATERIALS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 11
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    Polymer matrix composites research at NASA Lewis Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2006-04-12
    Description: The in situ polymerization of monomer reactants (PMR) approach was demonstrated to be a powerful approach for solving many of the processing difficulties associated with the use of high temperature resistant polymers as matrix resins in high performance composites. The PMR-15 polyimide provides the best overall balance of processing characteristics and elevated temperature properties. The excellent properties and commercial availability of composite materials based on PMR-15 led to their acceptance as viable engineering materials. The PMR-15 composites are used to produce a variety of high quality structural components.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA. Langley Research Center Advan. Mater. Technol.; p 65-90
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  • 12
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    Transient thermocapillary flow in thin liquid layers (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 24 p
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  • 13
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    Surface-tension gradient induced flows at reduced gravity, introduction (1980)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 21 p
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  • 14
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    Corrosion protection coating (1982)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: NONMETALLIC MATERIALS
    Type: NASA Technol. Appl. Team; p 40
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  • 15
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    Ion beam deposition of amorphous carbon films with diamond like properties (1982)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Carbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 micron/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.
    Keywords: NONMETALLIC MATERIALS
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  • 16
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    A numerical study of the effects of heat diffusion through the base of the mixed layer (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In the present paper, a simple numerical model is used to study the warming of the mixed layer during the early summer. It is shown that the springtime temperature increase in the layer below the mixed layer (for example, in the cold pool on a continental shelf) has a maximum value which occurs for a limiting value of the surface heat flux. This is a result of the positive feedback at large Richardson numbers between stability and vertical diffusion of heat. The springtime temperature increase in the mixed layer increases nonlinearly with surface heat flux, because of the same positive feedback. The effects of interseasonal fluctuations of the surface heat flux on the spring and summer mixed layer and deeper temperature increases can be as great as the effect of interseasonal fluctuations of the average heat flux.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Geophysical Research; 85; Sept. 20
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  • 17
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    Thermal stability and aging of some new anaerobic adhesives for structural binding (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Polyurethane-modified high impact anaerobic adhesives have been chosen for a bonding application where impact cushion is critical. These adhesives meet all the requirements for high rate production and automatic assembly techniques. With aluminum adherends, one selected adhesive cured at room temperature with the recommended activator retained sixty percent of its original impact strength after twenty-six week aging at 100 C. The impact strength aging, the thermogravimetric analysis results, the outgassing data, and other observations made in this work indicate that the adhesives cured by simple heating give a more durable bond than that cured with an activator at room temperature.
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly; 11; July 198
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  • 18
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    New class of asymmetric shapes of rotating liquid drops (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Shapes and stability of surface-tension-endowed drops rotating rigidly at fixed angular momentum are calculated by finite-element analysis. A new family of asymmetric two-lobed drop shapes is discovered that branches from, and rejoins, the Pik-Pichak family of symmetric two-lobed shapes. The computations are verified for axisymmetric and symmetric two-lobed drop shape by comparison with previous approximations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review Letters; 45; July 21
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  • 19
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    Synthesis of perfluoroalkylether triazine elastomers (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A method of perfluoroalkylether triazine elastomer synthesis is described. To form an elastomer, the resultant polymer is heated in a closed oven at slightly reduced pressures for 1-day periods at 100, 130 and 150 C. A high-molecular-weight perfluoroalkylether triazine elastomer is produced that exhibits thermal and oxidative stability. This material is potentially useful in applications such as high-temperature seals, 'O' rings, and wire enamels.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Polymer Science; vol. 18
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  • 20
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    Release-rate calorimetry of multilayered materials for aircraft seats (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Multilayered samples of contemporary and improved fire-resistant aircraft seat materials were evaluated for their rates of heat release and smoke generation. Top layers with glass-fiber block cushion were evaluated to determine which materials, based on their minimum contributions to the total heat release of the multilayered assembly, may be added or deleted. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/cm2. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers
    Keywords: NONMETALLIC MATERIALS
    Type: SAMPE Quarterly; 11; Apr. 198
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  • 21
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    Normal and abnormal turbulent transport in a stratified medium (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The influences of memory effects, coupling between velocity and temperature fluctuations and tensorial transport properties on momentum and heat transfers in turbulent flow which do not follow the Boussinesq relation are examined. It is shown that the memory effect, represented by the Lagrangian of the velocity gradients, can account for the decoupling between the flux and the gradient, while the tensorial properties of the transport coefficients allow a normal Boussinesq-type transfer with memory and anomalous counter-gradient or gradient-less transport.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 22
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    Effect of temperature on surface noise (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An experimental work is discussed whose objective was to obtain data that show the effect of temperature and temperature fluctuations on surface noise. This was accomplished experimentally by immersing a small chord airfoil in the turbulent airstream of a hot jet. The theory and experiment reported by Olsen (1976) provided a guide for designing and validating the hot jet experiment and for interpreting the data. It is shown that increased temperature causes a small decrease in the sound levels; at the same time it causes a shift in the spectra that is smaller but similar to the shift observed with subsonic hot jet noise.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 18; Mar. 198
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  • 23
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    Morphological and frictional behavior of sputtered MoS2 films (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22387)
    Keywords: NONMETALLIC MATERIALS
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  • 24
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    Turbulent boundary layer heat transfer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Several environmental parameters presently acknowledged to affect heat transfer are discussed including: (1) the experimental apparatus used, (2) uniform and variable wall temperatures, (3) acceleration effects, (4) deceleration, (5) free stream turbulence, (6) surface roughness, (7) unsteady effects, and (8) secondary flows. Calculation procedures, and some physically based models that are successful in computing heat transfer rates are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 40 p
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  • 25
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    Curvature effects and turbulent boundary layers (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are examined from an experiment conducted to determine quantitatively the secondary factors which affect the response of a turbulent boundary layer to convex curvature and to examine the recovery process after curvature ended. The variation of Stanton number with streamwise distance and with enthalpy thickness Reynolds number for the baseline case is shown. The effect of delta sub .99/R on the velocity of the potential core would have if we extended to the wall with no viscous effects, of free stream acceleration, of an unheated starting length, and of boundary layer maturity are discussed. Mixing length and turbulent Prandtl number models are reviewed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 29 p
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  • 26
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    Analysis of the decay of temperature fluctuations in isotropic turbulence (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Lagrangian dispersion theory of Durbin (1980) is used to analyze experiments by Warhaft and Lumley (1978) and by Sreenivasan et al. (1980) on temperature fluctuations in grid-generated turbulence. Both theory and experiment show that the decay exponent m depends on the ratio of the initial length scales of velocity and temperature, although when this ratio is greater than 2.5 such dependence is negligible. The theory shows that m is not truly constant, but within the range covered by the experiments it is nearly so. The agreement between theory and experiment lends credence to the idea that the decay of fluctuations is controlled largely by turbulent relative dispersion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 25; Aug. 198
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  • 27
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    Axisymmetric inviscid swirling flows produced by bellmouth and centerbody (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The effect of large deformation in the flow between the bellmouth and centerbody is considered analytically for application to studies of vortex breakdown in a pipe. Basic equations are defined for axisymmetric inviscid swirling flows at the inflow and outflow sections. Axial and circumferential velocity component profiles are presented, and comparisons are made with trials involving vane angles of 42 deg and Re of 2300. Axial components of the prediction matched well in the inner half of the pipe radius and not well with the outer, while circumferential predictions were good only at the axis. A lack of viscosity was concluded to result in the inaccuracies near the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 20; Apr. 198
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  • 28
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    Gas diffusion in multibubble systems (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A model is proposed for the study of the growth and shrinkage of gas bubbles in systems containing many gas bubbles. The key feature of this model is the replacement of the bubbles by point sources of gas concentration. Calculations are performed in the simple case of an initial uniform array of bubbles of equal radii.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Chemical Engineering Science; 35; 1980
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  • 29
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    Vortex methods for flow simulation (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Recent progress in the development of vortex methods and their applications to the numerical simulation of incompressible fluid flows are reviewed. Emphasis is on recent results concerning the accuracy of these methods, improvements in computational efficiency, and the development of three-dimensional methods. Simulations of several example flows which display some of the strengths and weaknesses of vortex methods are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 37; Oct. 198
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  • 30
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    Dissolution of multicomponent bubbles (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The behavior of an isolated, stationary, multicomponent gas bubble in a glassmelt containing several dissolved gases is considered. The relevant mass-transport equations are formulated and calculations are performed for the case of two diffusing gases using a quasi-stationary model and a numerical solution of the exact mass-transfer equations. The results obtained from these two approaches are compared. The factors which govern the dissolution or growth of a bubble are thermodynamic and kinetic in origin. The tendency of a bubble to grow or shrink at long times is controlled by departure from overall equilibrium, whereas the short-time bubble dynamics may be dominated by kinetic effects. As a result of the existence of these dual influences, maxima and/or minima occur in the functional dependence of the bubble radius on time.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 63
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  • 31
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    Photosensitized oxidation of unsaturated polymers (1980)
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    Publication Date: 2011-08-17
    Description: A review of the photosensitized oxidation of singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds is presented. The cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene) are studied, and their microstructural changes which occur on reaction with (IO2) in solution were investigated by infrared, (H-1) and (C-13) NMR spectroscopy. The polymers yielded allylic hydroperoxides with shifted double bonds according to the 'ene' mechanism of simple olefins. It was shown that single oxygenation of unsaturated polymers is similar to their low molecular weight analogs, and that the differences are due to secondary processes affecting the (IO2)-reacted polymers.
    Keywords: NONMETALLIC MATERIALS
    Type: Pure and Applied Chemistry; 52; 1980
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  • 32
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    Performance of Chevron-notch short bar specimen in determining the fracture toughness of silicon nitride and aluminum oxide (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Ease of preparation and testing are advantages unique to the chevron-notch specimen used for the determination of the plane strain fracture toughness of extremely brittle materials. During testing, a crack develops at the notch tip and extends stably as the load is increased. For a given specimen and notch configuration, maximum load always occurs at the same relative crack length independent of the material. Fracture toughness is determined from the maximum load with no need for crack length measurement. Chevron notch acuity is relatively unimportant since a crack is produced during specimen loading. In this paper, the authors use their previously determined stress intensity factor relationship for the chevron-notch short bar specimen to examine the performance of that specimen in determining the plane strain fracture toughness of silicon nitride and aluminum oxide.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Testing and Evaluation; 8; May 1980
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  • 33
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    Fracture toughness determination of Al2O3 using four-point-bend specimens with straight-through and chevron notches (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 63
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  • 34
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    Study of incompressible turbulent channel flow by large eddy simulation (1982)
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    Publication Date: 2011-08-18
    Description: Incompressible turbulent channel flow is investigated by large eddy simulation using improved numerical methods and boundary conditions. In downstream and spanwise directions, cyclic boundary conditions are imposed for velocity and pressure, and two types of boundary conditions near the wall are used and compared. One type is based on the logarithmic law of the mean velocity near the wall and has a slip boundary condition where the molecular-viscous term is neglected. The other type is based on a no-slip boundary condition, where fine mesh spacing near the wall is used to take account of the molecular viscosity. Although the present study employs a coarse mesh (16 x 16 x 21), its results are in good agreement with those of Moin and Kim (1981).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 35
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    Developing flow in S-shaped ducts (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The velocity characteristics of laminar and turbulent developing flow in an S-duct formed from two 22.5-deg bends of rectangular cross-section have been studied experimentally using laser Doppler velocimetry. It is shown that pressure-driven secondary flows arise in the first bend of the duct and reach maxima of 0.22 and 0.15 of the bulk velocity in the laminar and turbulent flows, respectively. The velocities are greater in the laminar flow, mainly because of the thicker inlet boundary layers. On passing through the second half of the S-duct, a secondary flow is established over most of the section in the direction opposite to that in the first half. Near the outer wall of the second bend, however, the secondary flow generated in the first bend is sustained because of the local sign of radial vorticity. This effect contributes to a redistribution of the streamwise isotachs, by the end of the duct, comparable with that in unidirectional bends.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 36
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    Stability of erythrocyte suspensions layered on stationary and flowing liquids (1982)
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    Publication Date: 2011-08-18
    Description: The apparent stability of erythrocyte suspensions layered on stationary and flowing Ficoll solutions was studied considering the effects of particle concentration, type and size, and the different flow rates of the particle suspensions and chamber liquid. The data from the flowing system were empirically fitted and, when extrapolated to zero chamber liquid flow rate, gave values comparable to the data from the stationary system, thus confirming the validity of the data and our approach to obtain that data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Separation Science and Technology; 17; 6, 19; 1982
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  • 37
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    Performance of laser-glazed zirconia thermal barrier coatings in cyclic oxidation and corrosion burner rig tests (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22346)
    Keywords: NONMETALLIC MATERIALS
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  • 38
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    Some properties of r.f.-sputtered hafnium nitride coatings (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-21331)
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  • 39
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    Sputtered silicon nitride coatings for wear protection (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20314)
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  • 40
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    The combined effects of Fe and H2 on the nitridation of silicon (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In view of the support offered by previous work for the suggestion that Fe may affect alpha-Si3N4 formation and microstructural development, a two-part study was conducted to differentiate the effects of H2 and Fe in, first, the nitridation of pure and of Fe-containing powder in N2 and N2-4% H2, and then the nitridation of (1 1 1) Si single crystal wafers with and without Fe powder on the surface. The degree of nitridation is most strongly affected by H2 at 1200 C, but by Fe at 1375 C, where Fe-containing samples in either atmosphere were almost completely nitrided. While neither H2 nor Fe alone changed the ratio of alpha-Si3N4 to beta-Si3N4, the combination of H2 and Fe increased it at both temperatures.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Materials Science Letters; 1; Aug. 198
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  • 41
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    Experimental studies of the vapor phase nucleation of refractory compounds. I - The condensation of SiO (1982)
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    Publication Date: 2011-08-18
    Description: The critical partial pressure of SiO necessary to initiate avalanche nucleation in the SiO-H2 system is measured as a function of the ambient temperature in the range 750-1000 K. Results show that the condensate produced at low temperatures is Si2O3, while a mixture of Si2O3 and amorphous SiO2 is produced at high temperatures. A surface energy of approximately 500 ergs/sq cm for the particles is found by analyzing the critical partial pressure vs temperature using classical nucleation theory. It is concluded that classical nucleation theory is not applicable to this system, because several inconsistencies in the thermodynamic analysis are demonstrated, and it is suggested that a kinetic theory of nucleation may be the preferential way to describe the condensation process.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Chemical Physics; 77; Sept. 1
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  • 42
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    Cauchy integral method for two-dimensional solidification interface shapes (1982)
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    Publication Date: 2011-08-18
    Description: A method is developed to determine the shape of steady state solidification interfaces formed when liquid above its freezing point circulates over a cold surface. The solidification interface, which is at uniform temperature, will form in a shape such that the non-uniform energy convected to it is locally balanced by conduction into the solid. The interface shape is of interest relative to the crystal structure formed during solidification; regulating the crystal structure has application in casting naturally strengthened metallic composites. The results also pertain to phase-change energy storage devices, where the solidified configuration and overall heat transfer are needed. The analysis uses a conformal mapping technique to relate the desired interface coordinates to the components of the temperature gradient at the interface. These components are unknown because the interface shape is unknown. A Cauchy integral formulation provides a second relation involving the components, and a simultaneous solution yields the interface shape.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 25; July 198
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  • 43
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    Calculation of radiation from argon shock layers (1982)
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    Publication Date: 2011-08-18
    Description: The accuracy of calculations of the radiation emissions from argon plasmas produced by the shock layers over blunt bodies is assessed. The existing theoretical and experimental spectroscopic data on argon are collated. A set of such data is selected for use in the radiative transfer calculations. Calculations are performed for the stagnation regions of the shock layers over laboratory-sized models using these data, and the results are compared with the existing experimental results obtained in a shock-tube. Through this comparison and a parametric study it is shown that radiative heat fluxes at the stagnation point in an argon environment can be calculated within an uncertainty of about 15%. It is shown also that radiative heat fluxes of the order of 100 kW/sq cm can be produced in the existing laboratory facilities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 28; July 198
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  • 44
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    Compliance calibration of the short rod chevron-notch specimen for fracture toughness testing of brittle materials (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The short rod chevron-notch specimen has the advantages of (1) crack development at the chevron tip during the early stage of test loading, and (2) convenient calculation of plane-strain fracture toughness from the maximum test load and from a calibration factor which depends only on the specimen geometry and manner of loading. For generalized application, calibration of the specimen over a range of specimen proportions and chevron-notch configurations is necessary. Such was the objective of this investigation, wherein calibration of the short rod specimen was made by means of experimental compliance measurements converted into dimensionless stress intensity factor coefficients.
    Keywords: NONMETALLIC MATERIALS
    Type: International Journal of Fracture; 18; Feb. 198
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  • 45
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    Dynamics of solid dispersions in oil during the lubrication of point contacts. II - Molybdenum disulfide (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-20275)
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  • 46
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    Test methodology for evaluation of fireworthy aircraft seat cushions (1982)
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    Publication Date: 2011-08-18
    Description: Aircraft seat materials were evaluated in terms of their thermal performance. The materials were evaluated using (a) thermogravimetric analysis, (b) differential scanning calorimetry, (c) a modified NBS smoke chamber to determine the rate of mass loss and (d) the NASA T-3 apparatus to determine the thermal efficiency. In this paper, the modified NBS smoke chamber will be described in detail since it provided the most conclusive results. The NBS smoke chamber was modified to measure the weight loss of materials when exposed to a radiant heat source over the range of 2.5 to 7.5 W/cm sq. This chamber has been utilized to evaluate the thermal performance of various heat blocking layers utilized to protect the polyurethane cushioning foam used in aircraft seats. Various kinds of heat blocking layers were evaluated by monitoring the weight loss of miniature seat cushions when exposed to the radiant heat. The effectiveness of aluminized heat blocking systems was demonstrated when compared to conventional heat blocking layers such as neoprene. All heat blocking systems showed good fire protection capabilities when compared to the state-of-the-art, i.e., wool-nylon over polyurethane foam.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire and Flammability; 13; Jan. 198
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  • 47
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    Microstructure and property characterization of sintered Si3N4, SiC, and SiAlON (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Commercially-produced, pressureless sintered Si3N4, SiC, and SiAlON were characterized with respect to density, phases present, bend strength, and oxidation resistance. The room-temperature bend strengths of sintered Si3N4, SiC, and SiAlON are comparable. However, the room-temperature strengths are much lower (approximately 40 to 50%) than the room-temperature strength of hot-pressed Si3N4 (NC-132). The strength loss in Si3N4 and SiAlON materials at high temperature was attributed to a viscous grain-boundary phase, retained during cooling from the sintering temperature. The oxidation resistance of sintered alpha-SiC was the best of any materials tested.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 65
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  • 48
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    Behavior of bubbles in glassmelts. II - Dissolution of a stationary bubble containing a diffusing and a nondiffusing gas (1980)
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    Publication Date: 2011-08-18
    Description: The effect of a foreign nondiffusing gas on the rate of shrinkage of an oxygen bubble in a soda-lime-silica melt was studied. The rate of change of bubble radius with time was computed using the quasi-stationary approximation. The effects of melt undersaturation and initial fraction of foreign gas in the bubble are considered and compared with those calculated using previously derived expressions.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 63
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  • 49
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    A new brominated polymeric additive for flame retardant glass-filled polybutylene terephthalate (1982)
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    Publication Date: 2011-08-18
    Description: Attention is called to the undesirable effects (poor ultraviolet light stability and blooming) sometimes introduced by brominated flame retarders. A brominated polymeric additive (BPA) with little or none of these undesirable side effects is compared with decabromobiphenyl oxide (DBBPO). The additive bears the product name F-2300. It is found to be more easily dispersed than DBBPO. The F-2300 is as effective as the DBBPO in the oxygen index test. The improved efficiency of the F-2300 may be explained by its better dispersion in polybutylene terephthalate (PBT). Glass-filled PBT containing F-2300 is found to be more resistant to UV degradation than DBBPO-containing formulas. Formulations with F-2300 therefore have a longer useful outdoor life. F-2300 is a diglycidyl-type polymer containing 50 percent aromatically bound bromine. Its melting point is 112 C, and it is stable up to 372 C. It is pointed out that since its melts at a relatively low temperature, it can be introduced into the formulation as a large agglomerate and still be dispersed evenly throughout the polymer.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire Retardant Chemistry; 9; Aug. 198
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  • 50
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    XPS, AES and friction studies of single-crystal silicon carbide (1982)
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    Publication Date: 2011-08-18
    Description: The surface chemistry and friction behavior of a single crystal silicon carbide surface parallel to the 0001 plane in sliding contact with iron at various temperatures to 1500 C in a vacuum of 3 x 10 nPa are investigated using X-ray photoelectron and Auger electron spectroscopy. Results show that graphite and carbide-type carbon are seen primarily on the silicon carbide surface in addition to silicon at temperatures to 800 C by both types of spectroscopy. The coefficients of friction for iron sliding against a silicon carbide surface parallel to the 0001 plane surface are found to be high at temperatures up to 800 C, with the silicon and carbide-type carbon at maximum intensity in the X-ray photoelectron spectroscopy at 800 C. The concentration of the graphite increases rapidly on the surface as the temperature is increased above 800 C, while the concentrations of the carbide-type carbon and silicon decrease rapidly and this presence of graphite is accompanied by a significant decrease in friction. Preheating the surfaces to 1500 C also gives dramatically lower coefficients of friction when reheating in the sliding temperature range of from room temperature to 1200 C, with this reduction in friction due to the graphite layer on the silicon carbide surface.
    Keywords: NONMETALLIC MATERIALS
    Type: Applications of Surface Science (ISSN 0378-5963); 10; 1982
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  • 51
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    Resonant entrainment of a confined pulsed jet (1982)
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    Publication Date: 2011-08-18
    Description: This paper reports the discovery of a new resonant entrainment phenomenon associated with a confined, pulsed jet flow. It was found that a confined jet, when pulsed at an organ-pipe resonant frequency of the confinement tube, experiences greatly enhanced entrainment and mixing near the exit end of the confinement tube compared to a steady confined jet. The mixing and entrainment rates for the resonantly pulsed confined jet approach, and in some cases slightly exceed, those for an unconfined pulsed jet. Both visual and quantitative evidence of this phenomenon is presented. The new effect should be of considerable interest in ejector and combustor design, both of which benefit from any enhancement in mixing between a primary and a secondary flow
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 52
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    Use of thermocapillary migration in a controllable heat valve (1982)
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    Publication Date: 2011-08-18
    Description: In accordance with the Marangoni effect, immiscible droplets in a host fluid in which a temperature gradient exists move in the direction of increasing temperature. It is proposed that this thermocapillary migration could be used to construct a 'liquid wick' that would return the condensed vapor at the condenser end of a heat pipe back to the evaporator, thus completing the fluid circuit. The droplets would be formed by capillary pressure forcing the condensate through a perforated diaphragm whose temperature would control the droplet flux, and hence the heat flux between the two ends of the heat pipe, thus making it a controllable heat valve.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Applied Physics; 53; Dec. 198
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  • 53
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    Charging and discharging characteristics of dielectric materials exposed to low- and mid-energy electrons (1982)
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    Publication Date: 2011-08-18
    Description: Charging and discharging characteristics of dielectric samples exposed to 1-25 keV and 25-100 keV electrons in a laboratory environment are reported. The materials examined comprised OSR, Mylar, Kapton, perforated Kapton, and Alphaquartz, serving as models for materials employed on spacecraft in geosynchronous orbit. The tests were performed in a vacuum chamber with electron guns whose beams were rastered over the entire surface of the planar samples. The specimens were examined in low-impedance-grounded, high-impedance-grounded, and isolated configurations. The worst-case and average peak discharge currents were observed to be independent of the incident electron energy, the time-dependent changes in the worst case discharge peak current were independent of the energy, and predischarge surface potentials are negligibly dependent on incident monoenergetic electrons.
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  • 54
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    Determination of boundary shape of cooled porous region (1982)
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    Publication Date: 2011-08-18
    Description: The shape of a cooled porous wall section is found that will provide a uniform surface temperature, as dictated by material limitations, when the surface is subjected to spatially nonuniform heating. In the analysis, local temperatures and pressures in the porous material are expressed in terms of a potential function. From the imposed thermal conditions, this potential function is governed by the dual constraints of both its value and its normal derivative being specified along the heated surface. The unknown shape of this surface is obtained by meeting these dual conditions. The analytical method uses a generalized conformal mapping procedure that includes a curved boundary. The coolant flow can be compressible or incompressible, and its viscosity can depend on temperature.
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  • 55
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    Oxygen index tests of thermosetting resins (1980)
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    Publication Date: 2011-08-17
    Description: The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Fire and Flammability; 11; Jan. 198
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  • 56
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    Carbon fiber production at low temperatures from polyacrylonitrile (1980)
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    Publication Date: 2011-08-18
    Description: Recent safety considerations have sought to lower the electrical conductivity of carbon fibers. Carbon fibers produced from polyacrylonitrile at low carbonization temperatures (600-900 C) possess low electrical conductivity but do not possess adequate strength. Low-temperature processes are described which improve fiber strength but do not increase electrical conductivity substantially. The processes result in a carbon fiber with nearly twice the tensile strength compared to the old process. Process development and its effect on fiber properties are reported.
    Keywords: NONMETALLIC MATERIALS
    Type: Textile Research Journal; 50; Oct. 198
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  • 57
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    Developments in fibrous refractory composite insulation (1980)
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    Publication Date: 2011-08-18
    Description: The development of a new insulation material for heat-shielding advanced reusable entry vehicles is reported. The material, called fibrous refractory composite insulation, is a composite of two ceramic fibers with no additional additives to bond the fibers together; it also includes silicon carbide, an emmittance agent, to improve its optical properties at high temperature. One fiber is a drawn 11-micron-diameter aluminoborosilicate fiber, the other fiber is the silica fiber (microquartz) used in producing silica RSI (reusable surface insulation for the Space Shuttle), which is a blown fiber of 1-3 micron diameter and variable length. A composition containing 20%, with a thermal shock resistance of 1.8 that of all silica insulation, has been successfully produced in a pilot plant.
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  • 58
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    Comparative evaluation of insulating properties of plasma-sprayed ceramic coatings (1980)
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    Publication Date: 2011-08-18
    Description: A simple method for evaluating the thermal insulating capability of ceramic coatings was devised. It is based on monitoring the temperature of the uncoated back surface of a thin superalloy disk while its front surface, coated with the ceramic material, is exposed to the high-temperature environment of an electric muffle furnace. The results obtained indicate that zirconia containing 8 wt% Y2O3 is a better thermal insulator than barium zirconate or calcium orthosilicate.
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  • 59
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    Determination of the orientation symmetry axis of graphite specimens (1980)
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    Publication Date: 2011-08-18
    Description: A technique is described for determining the true orientation symmetry axis of graphite specimens from conventional X-ray diffraction data. The technique, although developed for graphite, is applicable to any material exhibiting crystalline orientation which is symmetric about some axis. The requisite equations are derived for applying the procedure to both Bacon transmission data and rotating specimen reflection data. Results are presented which show that the symmetry axis of eleven molded graphites tested differed significantly from their nominal pressing directions.
    Keywords: NONMETALLIC MATERIALS
    Type: Carbon; 18; 3-E,; 1980
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  • 60
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    Vortex methods for two- and three-dimensional flow simulations (1980)
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    Publication Date: 2011-08-18
    Description: The point vortex and vortex blob methods for two dimensional flows are presented. Several results are discussed concerning the numerical analysis of the latter scheme, e.g., the preservation of globally conserved quantities and the analysis of the spatial discretization error resulting from the convection of fixed blobs of vorticity. An application to the two dimensional mixing layer is briefly described. The contour dynamics method is also discussed. The simulation of three dimensional flows with vortex methods is discussed. A natural way to represent the vorticity is in the form of closed tubes of filaments of vorticity, although other schemes are examined. Applications to aircraft trailing vortices and to a turbulent spot in a laminar boundary layer are presented. Hybrid schemes that use an Eulerian mesh to solve the Poisson equation for the velocity field are discussed. The goal of these schemes is to avoid the high cost of the Biot-Savart integration if many vortex elements are used while enjoying most of the advantages of pure Lagrangian schemes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Computational Fluid Dyn., Vol. 2; 52 p
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  • 61
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    Exchange of stability for a column of fluid with variable Rayleigh number under free boundary conditions (1980)
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    Publication Date: 2011-08-18
    Description: The exchange of stabilities is demonstrated for a system with harmonic boundary conditions. The motion of fluid in the presence of temperatures gradients is described. It is shown that this principle holds under free, but not rigid or semirigid, boundary conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 62
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    Measurement of velocity fields in fluid dynamics experiments (1980)
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    Publication Date: 2011-08-18
    Description: A microcomputer-video system was used to measure both spatial and temporal variations of two dimensional fluid flow velocity fields. The system utilizes two methods: the first method is the traditional one in which tracers are introduced into the fluid and their position compared at two closely spaced times; and the second method involves scattering coherent light in the fluid and obtaining motion by analyzing the multiple exposed speckle pattern recorded on photographic film.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 6 p
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  • 63
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    Stability of the stratifield cylindrical annulus flow (1980)
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    Publication Date: 2011-08-18
    Description: The linear stability analysis for the stratified flow between two rotating circular cylinders is formulated. Two approaches for the stability analysis are presented. The first approach results in an algebraic eigenvalue problem, while the second results in an initial value problem for the perturbation function. The advantages and disadvantages of both approaches are discussed and a preferable numerical solution technique is outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 13 p
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  • 64
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    Axially symmetric motion of a rotating stratified fluid (1980)
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    Publication Date: 2011-08-18
    Description: The spherical modeling of geophysical fluid flow is examined. In particular the extension of some previous work done in spherical geometry to the specific case of interest in the Spacelab atmospheric circulation experiment is discussed. This involves changing the boundary conditions under which the basic equations are to be solved. For simplicity the linear, axially symmetric steady state solution is sought.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 65
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    Experimental investigation of a three dimensional turbulent boundary layer with a non disappearing pressure gradient (1980)
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    Publication Date: 2011-08-17
    Description: The results of measuring profiles of temporally determined velocities and Reynolds tension, wall shear stresses and pressure distribution in a three dimensional, turbulent boundary layer with pressure gradients in both tangential directions are reported. For determining the velocities X wire probes were used whose cooling was gauged according to magnitude and direction of the flow and was described with an effective cooling speed. In the evaluation consideration is given to the directional sensitivity of the hot wire. The ratio of the turbulence viscosities is calculated for both tangential directions and is found to be approximately N equals 1.2. Further, the profiles of the mixing path lengths for the flow direction are found to vary only slightly with increasing X-coordinates, while the boundary layer thickness increases substantially. The relationships of turbulent shear stress to turbulent, kinetic fluctuation energy is approximately constant over a large part of the boundary layer.
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  • 66
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    The shape and stability of rotating liquid drops (1980)
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    Publication Date: 2011-08-17
    Description: Equilibrium shapes and stability of rotating drops held together by surface tension are found by computer-aided analysis that uses expansions in finite-element basis functions. Shapes are calculated as extrema of appropriate energies. Stability and relative stability are determined from curvatures of the energy surface in the neighborhood of the extremum. Families of axisymmetric, two-, three-, and four-lobed drop shapes are traced systematically. Bifurcation and turning points are located and the principle of exchange of stabilities is tested. The axisymmetric shapes are stable at low rotation rates but lose stability at the bifurcation to two-lobed shapes. Two-lobed drops isolated with constant angular momentum are stable. The results bear on experiments designed to further those of Plateau (1863).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Examination of group-velocity criterion for breakdown of vortex flow in a divergent duct (1980)
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    Publication Date: 2011-08-17
    Description: A group-velocity criterion for vortex breakdown implied by wave trapping theory is applied to vortex flows in a slightly divergent duct that exhibits breakdown. The group velocities for both symmetric (n = 0) and nonsymmetric (n = plus or - 1) modes of wave propagation are calculated for the experimental data. It is found that the flow ahead of the breakdown region is always supercritical and stable to these modes of disturbances. However, the flow field behind the breakdown region may be either supercritical or subcritical to the modes n = 0 and n = 1, and always supercritical to mode n = -1. The flow field behind this breakdown region is unstable to the asymmetric mode disturbance (n = 1) for a finite range of wavenumbers. The calculated frequencies of the unstable disturbances are in good agreement with the frequencies obtained from the experimental measurements.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 23; May 1980
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  • 68
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    On the numerical solution of time-dependent viscous incompressible fluid flows involving solid boundaries (1980)
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    Publication Date: 2011-08-17
    Description: An inherent numerical problem associated with the fully explicit pseudospectral numerical simulation of the incompressible Navier-Stokes equation for viscous flows with no-slip walls is described. A semi-implicit scheme which circumvents this numerical difficulty is presented. In this algorithm the equation of continuity rather than the Poisson equation for pressure is solved directly. Pseudospectral formulation of the channel flow problem using Fourier series and Chebyshev polynomials expansions is given for this scheme. An example demonstrating the applicability of the method is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 35; May 1980
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  • 69
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    Simulation of flat-plate turbulent boundary layers in cryogenic tunnels (1980)
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    Publication Date: 2011-08-17
    Description: The magnitudes of real-gas effects on flat-plate turbulent boundary layer simulations in a cryogenic nitrogen wind tunnel are investigated in order to determine the validity of the method used by Inger (1979) to estimate real-gas effects. Boundary layer solutions for real gases, ideal gases with a specific heat ratio of 1.6 and ideal diatomic gases (specific heat ratio 1.4) were obtained for the worst case conditions of maximum stagnation pressure (9 atm), minimum stagnation temperature (120 K) and Mach number of 1.2. Calculated boundary layer parameters such as friction coefficient and displacement thickness are shown to agree closely for the real gas and the ideal diatomic gas (specific heat ratio 1.4), while the ideal gas solution used by Inger is shown to differ from the real-gas values considerably. Results indicate that real-gas effects on a flat-plate turbulent boundary layer simulation in a cryogenic nitrogen tunnel are insignificant, and suggest the unlikelihood of the large real-gas effects reported by Inger for turbulent boundary layer shock interactions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Aircraft; 17; Apr. 198
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  • 70
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    Laser processing (1982)
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    Publication Date: 2011-08-18
    Description: Progress in the Progress ceramic materials is reported. Experiments and models for sintering and microstructure evolution are described. Models and data for understanding the kinetics of grain boundary motion and of pore coarsening and new materials for fuel cells and batteries; are developed. New experimental techniques using lasers for forming fine, monosized powders and for forming stable and metastable structures from liquids, and solar materials research are also developed. Colloidal science and ceramics processing are explored; and research programs on the presintering science necessary for controlled green microstructures are outlined.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 198-209
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  • 71
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    Evaluation of waveguide coating materials (1982)
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    Publication Date: 2011-08-18
    Description: Waveguide coating materials were tested at 8470 MHz for insertion loss. Samples of these coatings on waveguide pieces without flanges were tested in an environmental chamber to simulate the effects of high power microwave heating. Test results indicated that three types of coating materials are acceptable with regard to insertion loss. However, simulated microwave heating caused debonding of Metcot 7 and BD-991 coatings, resulting in peelings in the waveguide. The higher cost Chemglaze R104 does not exhibit this problem.
    Keywords: NONMETALLIC MATERIALS
    Type: The Telecommun. and Data Acquisition Rept.; p 68-71
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  • 72
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    Numerical modeling and optimization of polymer melt processing operations (1982)
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    Publication Date: 2011-08-18
    Description: The application of finite element computer analyses to polymer flows of the type encountered in melt processing operations is described. A code capable of predicting values of fluid veleocity, pressure, shear stress, and temperature at any point within the flow field was developed. As such, is is of value in diagnosing such processing problems as regions of fluid stagnation at which thermal degradation may occur, or regions of excessive shear deformation which lead to thermomechanical damage. It is further able to generate predictions of the forces which must be applied to the melt to achieve the desired flow, and this information is of value in designing processing equipment of optimal efficiency and minimum energy consumption.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 117-119
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  • 73
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    Rapid quenching effects in glassy polymers (1982)
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    Publication Date: 2011-08-18
    Description: Using a specially constructed microbalance for hydrostatic weighing, density changes in PVC thin film due to rapid quenching through the glass transition temperature were observed. The more severe the quench, the greater the free volume content. Isobaric volume recovery of PVC was also studied by volume dilatometry. Both show aging of relaxing molecular rearrangements taking place as a linear function of logarithmic aging time at room temperature. Distribution of retardation times and Primak's distributed activation energy spectra were applied to the volume recovery data. The concomitant changes in mechanical properties of PVC after quenching were monitored by tensile creep stress-stran to failure rates. All reflect the presence of excess free volume content due to rapid quenching.
    Keywords: NONMETALLIC MATERIALS
    Type: The Mater. Process. Res. Base of the Mater. Process. Center; p 79-89
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  • 74
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    Spouts in a bed of silica powder associated with fluidization by outgassing of adsorbed water (1982)
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    Publication Date: 2011-08-18
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Multiphase Flow; 8; 4, 19; 1982
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  • 75
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    On current aspects of finite element computational fluid mechanics for turbulent flows (1982)
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    Publication Date: 2011-08-18
    Description: A set of nonlinear partial differential equations suitable for the description of a class of turbulent three-dimensional flow fields in select geometries is identified. On the basis of the concept of enforcing a penalty constraint to ensure accurate accounting of ordering effects, a finite element numerical solution algorithm is established for the equation set and the theoretical aspects of accuracy, convergence and stability are identified and quantized. Hypermatrix constructions are used to formulate the reduction of the computational aspects of the theory to practice. The robustness of the algorithm, and the computer program embodiment, have been verified for pertinent flow configurations.
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  • 76
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    An analytical approach to thermal modeling of Bridgman-type crystal growth. I - One-dimensional analysis (1982)
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    Publication Date: 2011-08-18
    Description: A relatively simple one-dimensional thermal model of the Bridgman growth process has been developed which is applicable to the growth of small diameter samples with conductivities similar to those of metallic alloys. The heat flow in a translating rod is analyzed in a way that is applicable to Biot numbers less than unity. The model accommodates an adiabatic zone, different heat transfer coefficients in the hot and cold zones, and changes in sample material properties associated with phase change. The analysis is applied to several simplified cases. The effect of the rod's motion is studied in a three-zone furnace for a rod sufficiently long that end effects can be neglected; end effects are then investigated for a motionless rod. Finally, the addition of a fourth zone, an independently controlled booster heater between the main heater and the adiabatic zone, is evaluated for its ability to increase the gradient in the sample at the melt interface and to control the position of the interface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Crystal Growth; 58; 1982
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  • 77
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    Development of low-thermal expansion mullite bodies (1982)
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    Publication Date: 2011-08-18
    Description: A series of ceramic compositions based on variations in the crystal-glass ratio of a mullite body were developed. The thermal expansion of these compositions varies from 3.7 to 5.0 x 10 to the -6th/deg C to 800 C. The materials are particularly useful for applications involving silicon, in that an identical thermal expansion is available. The high-temperature creep data for the lower-expansion compositions are inferior as a result of their higher glass contents. Raw material sources and fabrication procedures for specific compositions are given.
    Keywords: NONMETALLIC MATERIALS
    Type: American Ceramic Society; vol. 65
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  • 78
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    Curved ducts with strong secondary motion - Velocity measurements of developing laminar and turbulent flow (1982)
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    Publication Date: 2011-08-18
    Description: Two orthogonal components of velocity and associated Reynolds stresses are determined in a square-sectioned, 90 degree bend of 2.3 radius ratio by utilizing laser-Doppler velocimetry for Reynolds numbers of 790 and 40,000. Results show that boundary layers at the bend inlet of 0.25 and 0.15 of the hydraulic diameter create secondary velocity maxima of 0.6 and 0.4 of the bulk flow velocity, respectively. It is concluded that the boundary layer thickness is important to the flow development, mainly in the first half of the bend, especially when it is reduced to 0.15 of the hydraulic diameter. Smaller secondary velocities are found for turbulent flow in an identical duct with a radius ratio of 7.0 than in the strongly curved bend, although their effect is more important to the streamwise flow development because of the smaller pressure gradients. In addition, the detail and accuracy of the measurements make them suitable for evaluation of numerical techniques and turbulence models.
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  • 79
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    Numerical solutions for the spin-up of a stratified fluid (1982)
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    Publication Date: 2011-08-18
    Description: The model of Warn-Varnas et al. (1978) is used to numerically examine the spin-up flow of a thermally stratified fluid in a cylinder with an insulating side wall, and comparison of the results with the laser-Doppler measurements of Lee (1975) shows excellent agreement. It is shown that flow gradients are created in the interior of the fluid during the meridional circulation spin-up phase, and that the azimuthal flow decayed faster than has been predicted by Wallin (1969). It is established that viscous diffusion in the interior, arising from the interior-flow gradients, is the cause of the discrepancy with Wallin's theory.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 117; Apr. 198
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  • 80
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    Addition polyimide adhesives containing various end groups (1982)
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    Publication Date: 2011-08-18
    Description: Addition polyimode oligomers have been synthesized from 3,3 prime, 4,4 prime-benzophenone tetracarboxylic acid dianhydride and 3,3 prime-methylenedianiline using a variety of latent crosslinking groups as end-caps. The nominal 1300 molecular weight imide prepolymers were isolated and characterized for solubility in amide, chlorinated and ether solvents, melt-flow and cure properties, glass transition temperature, and thermal stability on heating in an air atmosphere. Adhesive strengths of the polyimides were obtained both at ambient and elevated temperatures before and after aging at 232 C. Properties of the novel addition polyimides were compared to a known nadic end-capped adhesive, LARC-13.
    Keywords: NONMETALLIC MATERIALS
    Type: Polymer Engineering and Science; 22; 1, Ja; Jan. 198
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  • 81
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    Topology of three-dimensional separated flows (1982)
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    Publication Date: 2011-08-18
    Description: A Legendre formulation for a pattern of streamlines adjacent to a surface considered as trajectories with properties consistent with those of a constant vector field is used to develop a mathematical framework for three-dimensional separated flows. Convergence of skin-friction lines onto a particular skin-friction line originating from a particular saddle point is defined as a necessary condition for flow separation. Steady, three-dimensional flow is considered, and singular points occurring in the skin-friction lines are shown to happen where the skin friction or the surface vorticity become zero, and become nodal or saddle points. The separation initiates and continues only globally, as a mixture of an infinite set of friction lines, or locally, with one line. The topography of streamlines in two-dimensional sections of three-dimensional flows is discussed, and examples are provided of a round-nosed body of revolution at varying angles of attack.
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  • 82
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    Heat transfer from combustion gases to a single row of closely spaced tubes in a swirl crossflow Stirling engine heater (1982)
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    Publication Date: 2011-08-18
    Description: This paper describes an experimental program to determine the heat-transfer characteristics of a combustor and heat-exchanger system in a hybrid solar receiver which utilizes a Stirling engine. The system consists of a swirl combustor with a crossflow heat exchanger composed of a single row of 48 closely spaced curved tubes. In the present study, heat-transfer characteristics of the combustor/heat-exchanger system without a Stirling engine have been studied over a range of operating conditions and output levels using water as the working fluid. Nondimensional heat-transfer coefficients based on total heat transfer have been obtained and are compared with available literature data. The results show significantly enhanced heat transfer for the present geometry and test conditions. Also, heat transfer along the length of the tubes is found to vary, the effect depending upon test condition.
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  • 83
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    Effect of X-ray flux on polytetrafluoroethylene in X-ray photoelectron spectroscopy (1982)
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    Publication Date: 2011-08-18
    Description: The effect of the X-ray flux in X-ray photoelectron spectroscopy (STAT) on the constitution of the polytetrafluoroethylene (PTFE) surface has been examined. The radiation dose rate for our specimen was about 10 to the 7th rad/s. The structure, magnitude and binding energy of the C(1s) and F(1s) features of the XPS spectrum and the mass spectrum of gaseous species evolved during irradiation are observed. The strong time dependence of these signals over a period of several hours indicated that the surface constitution of PTFE is greatly affected by this level of radiation dose. The results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.
    Keywords: NONMETALLIC MATERIALS
    Type: Journal of Vacuum Science and Technology; 20; Feb. 198
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  • 84
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    The dependence of the shape and stability of captive rotating drops on multiple parameters (1982)
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    Publication Date: 2011-08-18
    Description: Asymptotic and numerical techniques in bifurcation theory are applied to the Young-Laplace equation governing meniscus shape in order to analyze the dependence of the shape and stability of rigidly rotating drops held captive between corotating solid faces on multiple parameters. Asymptotic analysis of the evolution of drop shape from the cylindrical as a function of distance between the solid faces, drop volume, rotational Bond number and gravitational Bond number shows that some shape bifurcations from cylinders to wavy, axisymmetric menisci are ruptured by small changes in drop volume or gravity. Computer calculations of axisymmetric drop shapes based on a finite element representation of the interface and numerical algorithms for tracking shape families and singular points are then used to map drop stability for the four-dimensional parameter space. The results of the asymptotic and numerical analyses are shown to agree well within the limited range of parameters where the asymptotic analysis is valid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Philosophical Transactions, Series A (ISSN 0080-4614); 306; 1493,; Aug. 27
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  • 85
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    ADI on staggered mesh - A method for the calculation of compressible convection (1982)
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    Publication Date: 2011-08-18
    Description: An alternating direction implicit (ADI) method has been applied to a staggered grid for the computation of convection in a highly stratified fluid. Since artificial viscosity is not needed, subtle effects like the onset of convection can be studied. These computations compare well with the 2-D results by Graham (1975) and also agree with standard Boussinesq results when taken to that limit. Good efficiency has been achieved with a time step hundreds of times larger than the stability limit imposed by the explicit treatment of diffusion and the Courant number is not restricted to be below 1. The Navier-Stokes equation contains cross spatial derivatives which are treated explicitly in most ADI schemes. The destabilizing effect of such a practice on a 2-D model system with second-order spatial derivative terms only was analyzed and found to be not excessive.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 47; July 198
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  • 86
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    Creep of plasma-sprayed-ZrO2 thermal-barrier coatings (1982)
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    Publication Date: 2011-08-18
    Description: Specimens of plasma-sprayed-zirconia thermal-barrier coatings with three different porosities and different initial particle sizes were deformed in compression at initial loads of 6900, 13,800, and 24,100 kPa (1000, 2000, and 3500 psi) and temperatures of 1100, 1250, and 1400 C. The coatings were stabilized with lime, MgO, and two different concentrations of Y2O3. Creep began as soon as the load was applied and continued at a constantly decreasing rate until the load was removed. Temperature and stabilization had a pronounced effect on creep rate while the stress, particle size, and porosity had a lesser effect. Creep deformation was due to cracking and particle sliding.
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  • 87
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    Some inelastic effects of thermal cycling on ZrO2-Y2O3 materials (1982)
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    Publication Date: 2011-08-18
    Description: An analysis has been developed which relates the effects of inelastic behavior of Y2O3 stabilized ZrO2 (YSZ) materials. The results show these materials to be sensitive to small changes in temperature and are supported by measurements of inelastic behavior in disk and bar specimens at temperatures as low as 1010 C (1850 F). At higher thermomechanical loads, the test specimens can deform to strains greater than 1 percent and for bar specimens, with sufficient strength, to remain bonded to the metallic substrate.
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    Use of fiber-like materials to augment cycle life of thick, thermoprotective-seal coatings (1982)
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-32633)
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  • 89
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    Effects of arc current on the life in burner-rig thermal cycling of plasma-sprayed ZrO2-O3 (1982)
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-17453)
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  • 90
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    A ceramic nozzle for the NASA-Langley 2.4-m /8.0-ft/ high temperature structures tunnel (1982)
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    Publication Date: 2011-08-18
    Description: Two materials, a refractory castable ceramic and a SiO2-SiO2 composite, were fabricated as nozzle inserts for the Langley Research Center's 2.4-m (8.0-ft) high temperature structures tunnel. The high pressure and intense heat of the CH4-air products of the combustion-gas stream limits the materials that can be used in this tunnel. The castable-ceramic material showed good resistance to erosion and the thermal loads imposed on it by the gas stream but failed in tension when subjected to high hoop stresses. The SiO2-SiO2-composite nozzle insert withstood the thermomechanical loads but eroded unacceptably with increasing test temperature and pressure.
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  • 91
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    Some characteristics of polymers in composite materials and as electrical conductors (1982)
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    Publication Date: 2011-08-18
    Description: The characteristics of carbon fibers (CF) made from polyacrylonitrile (PAN) materials are discussed, together with research on conducting polymers. CF materials have better mechanical properties, chemical inertness, and higher stiffness than metallic materials but are subject to environmental instability, flammability, and delamination fatigue. Polymerization procedures for the monopolymer PAN are described, noting the use of SEM and X-ray diffraction techniques for studying the fiber structure. High modulus and strength of CF are caused by covalent sp(2) bonds in hexagonal carbon rings, which are stronger than the same links in diamonds. Details of the molecular chain structures and macroformations, stress-strain as a function of temperature, and thermosetting and glass transition temperatures of polymers are provided. Computational quantum chemistry techniques are being applied to studying electrical conductance in polymers, mainly to discover ways to stabilize the materials. Doped CH(x) has exhibited photovoltaic properties and other polymers have become superconductors at cryogenic temperatures.
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  • 92
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    A high-resolution numerical technique for inviscid gas-dynamic problems with weak solutions (1982)
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    Publication Date: 2011-08-18
    Description: The shock resolution of Harten's (1982) second-order explicit method for one-dimensional hyperbolic conservation laws is investigated for a two-dimensional gas-dynamic problem. The possible extension to a high resolution implicit method for both one- and two-dimensional problems is also investigated. Applications of Harten's method to the quasi-one-dimensional nozzle problem with two nozzle shapes (divergent and convergent-divergent) and the two-dimensional shock-reflection problem resulted in high shock resolution steady-state numerical solutions.
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  • 93
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    Numerical solution of viscous flow in unbounded fluid (1982)
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    Publication Date: 2011-08-18
    Description: Incompressible viscous flow fields induced by initial vorticity distributions with bounded support or exponential decay in the far field are investigated. A numerical scheme for the solution of the vorticity distribution and the velocity field is presented with special emphasis on the treatment of the boundary data. The efficiency of the scheme is demonstrated. The present method has been applied to the study of the merging and collision of vortex rings.
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  • 94
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    Simulation of large turbulent vortex structures with the parabolic Navier-Stokes equations (1982)
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    Publication Date: 2011-08-18
    Description: The theoretical basis for well posed marching of a Parabolic Navier-Stokes (PNS) computational technique for supersonic flow is discussed and examples given to verify the analysis. It is demonstrated that stable computations can be made even with very small steps in the marching direction. The method is applied to cones at large angle of attack in high Reynolds number, supersonic flow. Streamline trajectories generated from the numerical solutions demonstrate the development of vortex structures of the lee side of the cone. Previously announced in STAR as N83-22551
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  • 95
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    Relaxation solution of the full Euler equations (1982)
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    Publication Date: 2011-08-18
    Description: A numerical procedure for the relaxation solution of the full steady Euler equations is described. By embedding the Euler system in a second order surrogate system, central differencing may be used in subsonic regions while retaining matrix forms well suited to iterative solution procedures and convergence acceleration techniques. Hence, this method allows the development of stable, fully conservative differencing schemes for the solution of quite general inviscid flow problems. Results are presented for both subcritical and shocked supercritical internal flows. Comparisons are made with a standard time dependent solution algorithm. Previously announced in STAR as N82-24859
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    Pointwise and scanning laser anemometer measurements in steady and unsteady separated turbulent boundary layers (1982)
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    Publication Date: 2011-08-18
    Description: The physical features of steady and unsteady freestream separating turbulent boundary layers that have been determined by pointwise laser anemometer measurements are outlined. It is seen that the large-scale structures control the outer region's backflow behavior. Near the wall, the mean backflow velocity profile for both the steady and unsteady cases is found to scale on the maximum negative mean velocity and its distance from the wall. A description is given of a scanning laser anemometer that produces nearly instantaneous velocity profiles for examing the temporal features of these large-scale structures. Also described is a 'zero-wake' seeder that supplies particles to the outer shear layer and freestream flow with a minimal disturbance.
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    A new numerical method for the simulation of three-dimensional flow in a pipe (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new numerical technique for simulating three dimensional, unsteady, incompressible pipe flows is presented and its utility and accuracy is shown. Each vector function in the expansion of the velocity field is divergence free and satisfies the boundary conditions for viscous flow. Some of the benefits of the expansion technique are that pressure is eliminated from the dynamics, only two unknowns per mesh point are required, implicit treatment of the viscous terms is provided at no extra computational cost, and no fractional time steps are required. The method uses spectral expansions: Fourier series in the azimuthal and streamwise directions, and Jacobi polynominals in the radial direction. Previously announced in STAR as N82-31644
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 98
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    Numerical simulation of wall-bounded turbulent shear flows (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Developments in three dimensional, time dependent numerical simulation of turbulent flows bounded by a wall are reviewed. Both direct and large eddy simulation techniques are considered within the same computational framework. The computational spatial grid requirements as dictated by the known structure of turbulent boundary layers are presented. The numerical methods currently in use are reviewed and some of the features of these algorithms, including spatial differencing and accuracy, time advancement, and data management are discussed. A selection of the results of the recent calculations of turbulent channel flow, including the effects of system rotation and transpiration on the flow are included. Previously announced in STAR as N82-28577
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 99
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    Large eddy simulation of turbulent channel flow: ILLIAC 5 calculation (1980)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The capabilities of large eddy simulation in the prediction and analyses of wall-bounded turbulent shear flows are demonstrated. The dynamical equations for large scale field motions are derived. The computational grid network is described and its relation to the observed physical length scales in the flow are discussed. Some aspects of the mechanics and structure of the flow are examined both in the vicinity of the wall and in regions away from the wall. An attempt is made to correlate numerical results with laboratory observations. Other significant observations and conclusions are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Turbulent Boundary Layers; 18 p
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  • 100
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    Developments in the computation of turbulent boundary layers (1980)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Two methods of turbulence computation are discussed in terms of their basic simularities. It is shown that the two methods are interrelated and that each can gain from advances in the other. The degree of success of a pair of increasingly complex Reynolds stress models to broaden their range of applicability is examined through comparison with experimental data for a variety of flow conditions. An example of a large eddy simulation is presented, compared with experimental results, and used to evaluate the models for pressure rate of strain correlation and dissipation in the Reynolds averaged equations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Turbulent Boundary Layers; 23 p
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