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  • 42.75
  • DDC 510/.01
  • FLUID MECHANICS AND HEAT TRANSFER
  • 1975-1979  (1,113)
  • 1950-1954  (35)
  • 1
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    A numerical comparison with an exact solution for the transient response of a cylinder immersed in a fluid (1979)
    In:  CASI
    Details
    Publication Date: 2006-07-02
    Description: The transient response of an elastic cylindrical shell immersed in an acoustic media that is engulfed by a plane wave is determined numerically. The method applies to the USA-STAGS code which utilizes the finite element method for the structural analysis and the doubly asymptotic approximation for the fluid-structure interaction. The calculations are compared to an exact analysis for two separate loading cases: a plane step wave and an exponentially decaying plane wave.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 23-28
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  • 2
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    Numerical solution of compressible viscous flows (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The presented review is concerned with the problem of calculating compressible viscous flows. Basic numerical considerations and problems associated with calculating viscous flows are examined and current numerical approaches toward the solution of the Navier-Stokes equations are discussed. It is pointed out that the numerical solution of the full time-dependent equations for turbulent flow is not practical with present computers. Therefore, turbulence effects must be accounted for by modeling. Developments related to turbulence modeling are described. In connection with a discussion of numerical methods for solving viscous flow equations, attention is given to numerical domains of dependence of typical explicit and implicit methods, the diffusion problem, the convection-diffusion problem, and the split-hybrid method.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 3
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    The effect of external boundary conditions on condensation heat transfer in rotating heat pipes (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Experimental evidence shows the importance of external boundary conditions on the overall performance of a rotating heat pipe condenser. Data are presented for the boundary conditions of constant heat flux and constant wall temperature for rotating heat pipes containing either pure vapor or a mixture of vapor and noncondensable gas as working fluid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 22; Aug. 197
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  • 4
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    Turbulence generated by the interaction of entropy fluctuations with non-uniform mean flows (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The turbulence generated by random entropy fluctuations in an accelerating stream is analyzed. The results are obtained by using rapid distortion theory together with a high frequency solution of a previously developed wave equation that governs the small-amplitude unsteady vortical and entropic motion on steady potential flows (Goldstein, 1978). Simple results are obtained for the case of symmetric contraction, expansion or combination of the two. It is shown that the energy of the entropy-generated turbulence increases more rapidly with the contraction ratio of a subsonic flow than that of any imposed upstream turbulence. This result indicates that the entropy-generated turbulence may be more significant than the hydrodynamically generated turbulence in the turbine stages of aircraft engines.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 93; July 26
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  • 5
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    Transient ablation of Teflon in intense radiative and convective environments (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: On the basis of this investigation of the high-temperature behavior of polytetrafluoroethylene (PTFE), the transient one-dimensional ablation of PTFE has been developed by taking into account the optical transmittance of both the amorphous zone and the crystalline zone of PTFE layer. Results show that although the exposed surface receded at an apparently steady state, both the internal temperature and the thickness of the gel layer increase continuously due to the internal absorption of radiation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 17; June 197
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  • 6
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    Scattering and distortion of the unsteady motion on transversely sheared mean flows (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: It is shown that the pressure and velocity fluctuations of the unsteady motion on a transversely sheared mean flow can be expressed entirely in terms of the derivatives of two potential functions. One of these is a convected quantity that can be specified as a boundary condition and is related to a transverse component of the upstream velocity field. The other can be determined by solving an inhomogeneous wave equation whose source term is also a convected quantity that can be specified as a boundary condition in any given problem. The general theory is used to study the interaction of an unsteady flow with a semi-infinite plate embedded in a shear layer. The acoustic field produced by this interaction is calculated in the limits of low and high frequency. The results are compared with experimental one-third octave sound pressure level radiation patterns. The agreement is found to be excellent, especially in the low frequency range, where the mean-flow and convective effects are shown to have a strong influence on the directivity of the sound.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 91; Apr. 27
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  • 7
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    Laminar boundary-layer flow of non-Newtonian fluid (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A solution for the two-dimensional and axisymmetric laminar boundary-layer momentum equation of power-law non-Newtonian fluid is presented. The analysis makes use of the Merk-Chao series solution method originally devised for the flow of Newtonian fluid. The universal functions for the leading term in the series are tabulated for n from 0.2 to 2. Equations governing the universal functions associated with the second and the third terms are provided. The solution together with either Lighthill's formula or Chao's formula constitutes a simple yet general procedure for the calculation of wall shear and surface heat transfer rate. The theory was applied to flows over a circular cylinder and a sphere and the results compared with published data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 22; Oct. 197
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  • 8
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    Evolution of a rotating flow in the vicinity of a surface (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Evolution of a rotating flow in a body of fluid bounded by a stationary flat surface is discussed. The calculated results show that the radial pressure gradient is substantially reduced in the region close to the surface, so that letting that gradient be independent of distance from the surface would be expected to give only rough or qualitative estimates. However, the reduced rotation near the stationary surface is still large enough to cause an inflow near the surface and to set up a recirculation pattern. The concentration of vorticity by the radial inflow is not great enough to increase the tangential velocities near the center of rotation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 9
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    Solitary waves in stratified shear flows (1979)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An analysis is described of long, finite-amplitude internal waves in a stratified shear flow. Both regular and singular modes are considered with a nonlinear critical layer employed in the latter case. A three-layer model is used to develop the theory and closed-form expressions are obtained relating the phase speed to the Richardson number, the latter quantity being taken as O(1). The amplitude evolution equation is found to be either the Korteweg-de Vries equation or the Benjamin-Davis-Ono equation depending upon the distance of the more remote boundary from the edge of the shear layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Geophysical and Astrophysical Fluid Dynamics; 13; 1-3,; 1979
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  • 10
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    The shape of a pendent liquid drop (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Formal solutions of the static equilibrium equations for the form of the outer surface of a pendent liquid drop are studied. An approach is adopted in which only the one-parameter family determined by vertex height (u sub 0) need be described. Attention is restricted to rotationally symmetric configurations, and all symmetric solutions are characterized for the case where the Lagrange parameter lambda is equal to zero. It is shown that for any u sub 0 the function u(r; u sub 0) can be extended as a parametric solution of a system of equations for all arc lengths, yielding a curve without limit sets or double points, and that the resulting capillary rotation surface spreads out indefinitely away from the axis r = 0. The asymptotic form of the surface in the case of large absolute values of u sub 0 is characterized quantitatively, along with the global structure of all such surfaces.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 11
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    Transient thermal response of ablating bodies (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A numerical study of transient thermal response of a blunt-nosed axisymmetric body made of Teflon is presented using a two-layer thermal model. It is shown that phase change and transverse heat conduction have a considerable effect on the internal temperature field. Comparison of the numerical results with experimental data shows that the single-layer thermal model does not predict the real feature of the thermal field, whereas the results of the two-layer thermal model agree reasonably well with the experiment.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 17; Feb. 197
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  • 12
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    Comparison of a correlation term-discard closure for decaying homogeneous turbulence with experiment (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Turbulence decay is calculated by using experimental initial conditions and discarding quadruple-correlation terms in the correlation equations. Agreement with experiment is good only for moderately small times, but there are no perceptible negative spectral energies even at large times.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 22; Jan. 197
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  • 13
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    A computational fluid dynamic technique valid at the centerline for non-axisymmetric problems in cylindrical coordinates (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A technique is described for the numerical solution of non-axisymmetric flow problems posed in cylindrical coordinates when the z-axis is included in the flowfield. The highlight of the technique is the manner in which the singularities at the centerline are handled. Specifically, the governing flowfield equations at r = 0 are put in a special form by applying L'Hospital's Rule. The required radial derivatives are evaluated using a one-sided, second-order accurate, first-difference. This leads to a smooth, convergent calculation of the flowfield at the centerline. This appears to be the first generally applicable numerical method for avoiding coordinate system singularities in the context of a finite-difference scheme, and could have application to many nonaxisymmetric flows. The technique is illustrated by specific results for the time-dependent flowfield inside an internal combustion engine.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 30; Mar. 197
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  • 14
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    Surface tension driven convection (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: In a normal gravitational environment, the free surface of a liquid in a container plays a passive role in the transport processes. However, at microgravity, the free surface can become the dominant factor. A simple but meaningful spaceflight experiment is proposed to investigate the nature and extent of flows induced by surface-tension gradients along the free surface. The influences of container geometry, wetability, contamination, and imposed heating modes will be investigated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 43-51
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  • 15
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    Investigations on transparent liquid-miscibility gap systems (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Sedimentation and phase separation is a well known occurrence in monotectic or miscibility gap alloys. Previous investigations indicate that it may be possible to prepare such alloys in a low-gravity space environment but recent experiments indicate that there may be nongravity dependent phase separation processes which can hinder the formation of such alloys. Such phase separation processes are studied using transparent liquid systems and holography. By reconstructing holograms into a commercial-particle-analysis system, real time computer analysis can be performed on emulsions with diameters in the range of 5 micrometers or greater. Thus dynamic effects associated with particle migration and coalescence can be studied. Characterization studies on two selected immiscible systems including an accurate determination of phase diagrams, surface and interfacial tension measurements, surface excess and wetting behavior near critical solution temperatures completed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 21-35
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  • 16
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    Phase separation in transparent liquid-liquid miscibility gap systems (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A program to be carried out on transparent liquid-phase miscibility gap materials was developed for the purpose of acquiring additional insight into the separation process occurring in these systems. The transparency feature allows the reaction to be viewed directly through light scattering and holographic methods.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 3-17
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  • 17
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    Measurement of surface velocity fields (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A new technique for measuring surface velocity fields is briefly described. It determines the surface velocity vector as a function of location and time by the analysis of thermal fluctuations of the surface profile in a small domain around the point of interest. The apparatus now being constructed will be used in a series of experiments involving flow fields established by temperature gradients imposed along a surface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 36-42
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  • 18
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    The migration of fluid droplets and their interactions in a thermal gradient (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: When materials are processed in free fall, buoyant forces will be substantially reduced. Thus, the buoyant migration of droplets and bubbles which normally occurs on earth is expected to be overshadowed by migration due to other mechanisms in space processing. In particular, capillary forces on droplets due to the variation of interfacial tension around their periphery will play a significant role in governing their motion in space. While such interfacial tension gradients can be caused by thermal, compositional, and/or electrical gradients in the continuous phase, thermal gradients are convenient to use in controlled experimentation. On earth, due to interference from buoyant effects, it is difficult to study thermocapillary migration in sufficient detail. Also, the effects of a thermal gradient on the interactions among droplets are hard to study on Earth. Thus, an orbital facility for conducting experiments on the migration and interactions of fluid droplets in a continuous phase due to the action of a thermal gradient appears attractive.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 53-57
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  • 19
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    Measurement of diffusion coefficients from solution rates of bubbles (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The rate of solution of a stationary bubble is limited by the diffusion of dissolved gas molecules away from the bubble surface. Diffusion coefficients computed from measured rates of solution give mean values higher than accepted literature values, with standard errors as high as 10% for a single observation. Better accuracy is achieved with sparingly soluble gases, small bubbles, and highly viscous liquids. Accuracy correlates with the Grashof number, indicating that free convection is the major source of error. Accuracy should, therefore, be greatly increased in a gravity-free environment. The fact that the bubble will need no support is an additional important advantage of Spacelab for this measurement.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. UAH(NASA Workshop on Fluids Expt. System; p 18-20
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  • 20
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    Modular heat pipe radiator system study (1979)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-167829 , NAS 1.26:167829
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  • 21
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    Velocity field near the jet orifice of a round jet in a crossflow (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Experimentally determined velocities at selected locations near the jet orifice are presented and analyzed for a round jet in crossflow. Jet-to-crossflow velocity ratios of four and eight were studied experimentally for a round subsonic jet of air exhausting perpendicularly through a flat plate into a subsonic crosswind of the same temperature. Velocity measurements were made in cross sections to the jet plume located from one to four jet diameters from the orifice. Jet centerline and vortex properties are presented and utilized to extend the results of a previous study into the region close to the jet orifice.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-152293
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  • 22
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    Mobile tile glazing high density radiant heating system Model 1023/8. Preliminary manual and instruction manual (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-163705
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  • 23
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    Bellows flow-induced vibrations (1979)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Results of theoretical and experimental investigations of bellows typical of those found in space shuttle external tanks are presented. Correlation parameters are identified which generalize the alternating stress calculations cited in an earlier study. Alternating stress amplitudes and mean stress levels form the basis of a fatigue analysis incorporating seven ordinate charts for 347 stainless steel, alloy 21 6-9, and Inco 718. A crack propagation model is included with a program for computing bellows fatigue life. Two phase flow and material hardness properties are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-161308
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  • 24
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    Free convection about a rectangular prismatic crystal growing from a solution (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Sodium chlorate crystals growing from unstirred aqueous solutions were observed by Schlieren techniques. Growth rate data were best correlated by a Sherwood number with finite interface kinetics and a characteristic length equal to the crystal height plus the inverse reciprocal sum of the horizontal dimensions. The growth rate was slightly higher when the plume was laminar than when it was irregular. The horizontal growth rate was greater than the vertical growth rate, with the ratio tending to decrease with increasing plume instability. The threshold Grashof number for plume instability was greatly decreased with decreasing height for crystals with the same horizontal dimensions. The velocity of the eddies approached a constant value with increasing distance above the crystal surface, the terminal value being roughly proportional to the ratio of the square root of the Rayleigh number to the crystal characteristic length.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 22; Dec. 197
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  • 25
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    A new approach to the correlation of boundary layer mass transfer rates with thermal diffusion and/or variable properties (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A rational approach to the correlation of boundary layer mass transport rates, applicable to many commonly encountered laminar flow conditions with thermal diffusion and/or variable properties, is outlined. The correlation scheme builds upon already available constant property blowing/suction solutions by introducing appropriate correction factors to account for the additional ('pseudo' blowing and source) effects identified with variable properties and thermal diffusion. Applications of the scheme to the particular laminar boundary layer mass transfer problems considered herein (alkali and transition metal compound vapor transport) indicates satisfactory accuracy up to effective blowing factors equivalent to about one third of the 'blow off' value. As a useful by-product of the variable property correlation, we extend the heat-mass transfer analogy, for a wide range of Lewis numbers, to include variable property effects.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 22; Sept
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  • 26
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    Spectral characteristics of vortex breakdown flowfields (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Laser-Doppler anemometer measurements upstream and in the wakes of vortex breakdowns of bubble and spiral types are described. Spectral analysis of the data indicates prominent oscillations in the wakes at less than 10 Hz. These oscillations correspond closely to theoretical predictions of the linearly most unstable normal modes of the time-averaged mean flow profiles. The oscillations are more energetic, and vortex core expansions are greater for flows with a bubble form of vortex breakdown, which is therefore regarded as the stronger form of breakdown.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 22; Nov. 197
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  • 27
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    Experimental investigation of flow and heating in a resonance tube (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Experiments have been performed to determine the basic mechanism of heating in resonance tubes of square section with constant area excited by underexpanded jet flows. The jet flow between the nozzle exit and the tube inlet plays a key role in the performance of a resonance tube. A detailed and systematic investigation of the unsteady complex shock structure in this part of the flow region has led to a better understanding of the fundamental mechanisms associated with the gas heating in such tubes. A study of the effects of tube location in relation to free-jet shock location (without the presence of the resonance tube) has shed further light on the underlying mechanism of sustained oscillations of the flow in a resonance tube.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 94; Oct. 29
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  • 28
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    An experimental study of multiple jet mixing (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Measurements of an incompressible jet issuing from an array of rectangular lobes, equally spaced with their small dimensions in a line, both as a free jet, and as a confined jet, are carried out in three parts: (1) on a single rectangular free jet, (2) on the same jet in a multiple free jet configuration, and (3) on the same jet in a multiple jet configuration with confining surfaces (two parallel plates are symmetrically placed perpendicular to the long dimension of each lobe covering the entire flow field under consideration). In the case of a single rectangular free jet, the flow field of the jet is characterized by the presence of three distinct regions in the axial mean velocity decay and are referred to as: potential core region, two dimensional type region, and axisymmetric type region. In the case of a multiple free jet, the flow field for downstream distance X greater than 60D (D = width of a lobe) resembles that of a jet exiting from a two dimensional nozzle with its short dimension being the long dimension of the lobe.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-166184 , SU-JIAA-TR-23
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  • 29
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    Homogeneous vortex model for liquid slosh in spinning spherical tanks (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The problem of forced fluid sloshing in a partially filled spinning spherical tank is solved numerically using the finite element method. The governing equations include Coriolis acceleration, empirical fluid damping and spatially homogeneous vorticity first introduced by Pfeiffer. An exponential instability similar to flutter is detected in the present simulation for fill ratios below 50 percent. This instability appears in the model as a result of the homogeneous vortex assumption since the free slosh equations are neutrally stable in the Liapunov sense.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162725 , JPL-PUB-79-99
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  • 30
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    Effect of streamwise vortices on Tollmien-Schlichting waves (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The method of multiple scales is used to determine a first order uniform expansion for the effect of counter rotating steady streamwise vortices in growing boundary layers on Tollmien-Schlichting waves. The results show that such vortices have a strong tendency to amplify three dimensional Tollmien-Schlichting waves having a spanwise wavelength that is twice the wavelength of the vortices. An analytical expression is derived for the growth rates of these waves. These growth rates increase linearly with increasing amplitudes of the vortices.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162654 , VPI-E-79-12
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  • 31
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    Relaminarization of fluid flows (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The mechanisms of the relaminarization of turbulent flows are investigated with a view to establishing any general principles that might govern them. Three basic archetypes of reverting flows are considered: the dissipative type, the absorptive type, and the Richardson type exemplified by a turbulent boundary layer subjected to severe acceleration. A number of other different reverting flows are then considered in the light of the analysis of these archetypes, including radial Poiseuille flow, convex boundary layers, flows reverting by rotation, injection, and suction, as well as heated horizontal and vertical gas flows. Magnetohydrodynamic duct flows are also examined. Applications of flow reversion for turbulence control are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 32
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    Complete supersonic flowfields over blunt bodies in a generalized orthogonal coordinate system (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A general orthogonal coordinate system is used to describe various axisymmetric and two-dimensional shapes. Close approximations to planetary probe configurations are possible. The full Navier-Stokes equations are discretized in this coordinate system in a manner based on Allen and Cheng's numerical procedure. The blow shock is treated as a discontinuity which floats between grid points. Completely coupled flows over the forebody, base, and near wake were calculated over a cylinder, sphere, and an approximation to the Viking Aeroshell. Some problem areas in determining the base flow for increasing Reynolds number are discussed. In particular, it is found that the mean free path of the fluid near the wall immediately below the corner of the Viking Aeroshell, which experiences a severe expansion, can become greater than the local mesh size required to resolve the boundary layer in the forebody.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81784 , LOG-J11338
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    Recent improvements to the spinning body version of the EDDYBL computer program (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A conventional mixing length model specialized for thick boundary layers and a general model for pressure-strain correlation terms were added to the spinning version of EDDYBL. The models are discussed and modifications to the code input and output are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-152347 , DCW-R-24-01
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    The transfer of carbon fibers through a commercial aircraft water separator and air cleaner (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The fraction of carbon fibers passing through a water separator and an air filter was determined in order to estimate the proportion of fibers outside a closed aircraft that are transmitted to the electronics through the air conditioning system. When both devices were used together and only fibers 3 mm or larger were considered, a transfer function of .001 was obtained.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-159183
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    Potential heat exchange fluids for use in sulfuric acid vaporizers (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A series of perhalocarbons are proposed as candidate heat exchange fluids for service in thermochemical cycles for hydrogen production that involve direct contact of the fluid with sulfuric acid and vaporization of the acid. The required chemical and physical criteria of the liquids are described and the results of some preliminary high temperature test data are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162548 , JPL-PUB-79-81
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    GIM code user's manual for the STAR-100 computer (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The General Interpolants Method (GIM), a three dimensional, time dependent, hybrid procedure for generating numerical analogs of the conversion laws, is described. The Navier-Stokes equations written for an Eulerian system are considered. The conversion of the GIM code to the STAR-100 computer, and the implementation of 'GIM-ON-STAR' is discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3157 , LMSC-HREC-0568850
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    A fundamental study of liquid spray evaporation at a heated surface (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The influence of feedwater temperature and the influence of pulsing nozzle flow on the heat transfer characteristics in the spray evaporative cooling process were investigated. A commercial water circulation heater was installed in the feedwater line between the supply reservoir and the nozzle. A pass through the heater provided water at temperatures up to 50 C at the nozzle; higher temperatures were obtained by multiple heater passes. A thermocouple installed in the water line just upstream of the nozzle provided a measure of the feedwater temperature. Initial tests were run with belljar exhaust orifice number two which provided a pressure in a range about 7mm Hg abs. The feedwater temperature was heated to a temperature of 45 C. Results indicate that for a given system operating pressure, there is an upper limit on the feedwater temperature above which the spray will flash to vapor before hitting the surface to be cooled.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-160409
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    Evaporative cooling on a grooved surface (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The transition point where water begins to accumulate on the surface during spray evaporative cooling was investigated experimentally to determine the temperatures and corresponding heat flux at which this transition occurs. Several pressure ranges were considered including one below the triple point of water. Additionally, the results using a grooved surface were compared to those using a smooth surface. It was determined that a grooved surface has no effect on the heat transfer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-160410
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    Aerothermal performance of radiatively and actively cooled panel at Mach 6.6 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A flight-weight radiative and actively cooled honeycomb sandwich panel (RACP) was subjected to multiple cycles of both radiant and aerothermal heating. The 0.61 m by 1.22 m test specimen incorporated essential features of a full scale 0.61 m by 6.10 m RACP designed to withstand a heat flux of 136 kW/sq m. The panel consisted of heat shields, a thin layer of high temperature insulation, and an aluminum honeycomb sandwich panel with coolant tubes next to the sandwich skin. A 60/40 mass solution of ethylene glycol/water was used to cool the panel which successfully withstood a total of 3.5 hr of radiant heating and 137 sec exposure to an M = 6.6 test stream. Heat shield temperatures reached 1080 K (1945 deg R), and cooled-panel temperatures reached 382 K (687 deg R) midway between coolant tubes. Simulation of the full scale panel indicated that the full scale RACP would perform as expected. The tests revealed no evidence of coolant leakage or hot gas ingress which would seriously degrade the RACP performance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1595 , L-13355
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    A simplified model for the viscous crossflow in a slotted test section (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A simplified physical model was constructed which simulates the viscous crossflow in a fluid layer near the slots at a fixed streamwise location in a slotted wind tunnel. For low to moderate Reynolds numbers, numerical solutions of the two dimensional, incompressible Navier-Stokes equations in stream function and vorticity, which govern the model flow, were obtained. Fairly general slot geometry was incorporated by means of the Thompson-Thames-Mastin transformation. An approximate factorization scheme with cyclic acceleration parameters was employed to solve a finite difference analog of the stream function equation. The vorticity equation was numerically solved with a modified version of the classical alternating direction implicit scheme. Although no quantitative assessment of solution accuracy can be made, numerical results for variations in incremental wall pressure around the slat are at least qualitatively similar to some experimental results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3206
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  • 41
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    Application of data acquisition systems for on-line definition and control of wind tunnel shape (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Improvements in wind tunnel design to reduce test and flight discrepancies are analyzed. Flexible wall streamlining, criteria for tunnel streamlining, and error assessment are discussed. It is concluded that the concept of self-streamlining wind tunnels is suited for on-line computer control.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Data Acquisition Systems and Data Analysis in Fluid Dyn.; 46 p
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    A method of estimating self-diffusion coefficients in liquids (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIChE Journal; 25; Jan. 197
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  • 43
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    A statistical model of turbulence in two-dimensional mixing layers (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A statistical model of turbulence in fully developed two-dimensional incompressible turbulent mixing layers is proposed. The development of this model is largely motivated by the recent experimental observations of Brown and Roshko (1974). The model is based on the proposition that the turbulence of a fully developed two-dimensional incompressible mixing layer is in a state of quasi-equilibrium. The model is used to predict the second-order turbulence statistics of the flow including single-point turbulent Reynolds stress distribution, intensity of turbulent velocity components, rms turbulent pressure fluctuations, power spectra and two-point space-time correlation functions. It is shown that numerical results compare favorably with available experimental measurements.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 92; May 28
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    Scattering of emitted radiation from inhomogeneous and nonisothermal layers (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A parametric study is performed for the exiting monochromatic intensities scattered from finite plane-parallel inhomogeneous layers that are driven solely by a distribution of thermal sources. Intensities are obtained by invariantly imbedding the standard and thermal scattering functions. The single-scattering albedo and the Henyey-Greenstein phase-function parameter are varied independently, and both linear and exponential profiles are considered. Linear temperature profiles are used, including temperature inversions. The resulting intensities, as a function of the direction cosine of propagation, are discussed from a remote-sensing point of view. For an isothermal and homogeneous medium, the gross characteristics of the exiting intensity, represented by its overall slope, mean value (magnitude), and an interior maximum value, can be related to the total optical depth, single-scattering albedo, and phase function, respectively. For a homogeneous medium, linearly decreasing (in the line of sight) temperature profiles tend to obscure the phase-function information and decrease the apparent optical depth. On the other hand, linearly increasing temperature profiles tend to retain phase-function information and increase the apparent optical depth. Temperature inversion profiles give intensities very similar to those for purely linear profiles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 21; Mar. 197
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    Numerical results for the thermal scattering functions (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A recent formulation in radiative transfer defined the thermal scattering functions that characterize radiative transfer from a general plane-parallel finite medium driven solely by an internal distribution of thermal sources. Exiting diffuse intensities are expressed as space convolutions of the thermal scattering functions with any thermal source distribution. A parametric study is presented to obtain the basic structure of these scattering functions. The independent variables of these azimuthally independent functions are the direction cosine and source location, while the parameters are the single-scattering albedo, total optical depth, and the asymmetry factor in the Henyey-Greenstein phase function. The basic functional trends are discussed by using various parametric plots, and selected results are given to allow numerical checks. The computational method is invariant imbedding.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 21; Mar. 197
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    Evaluation of subgrid-scale models using an accurately simulated turbulent flow (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A calculation of periodic homogeneous isotropic turbulence is used to simulate the experimental decay of grid turbulence. The calculation is found to match the experiment in a number of important aspects and the computed flow field is then treated as a realization of a physical turbulent flow. From this flow, a calculation is conducted of the large eddy field and the various averages of the subgrid-scale turbulence that occur in the large eddy simulation equations. These quantities are compared with the predictions of the models that are usually applied in large eddy simulation. The results show that the terms which involve the large-scale field are accurately modeled but the subgrid-scale Reynolds stresses are only moderately well modeled. It is also possible to use the method to predict the constants of the models without reference to experiment. Attempts to find improved models have not met with success.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 91; Mar. 9
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    A relationship between maximum packing of particles and particle size (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Experimental data indicate that the volume fraction of particles in a packed bed (i.e. maximum packing) depends on particle size. One explanation for this is based on the idea that particle adhesion is the primary factor. In this paper, however, it is shown that entrainment and immobilization of liquid by the particles can also account for the facts.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Powder Technology; 22; 1979
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    Turbulent shear stresses in compressible boundary layers (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Hot-wire anemometer measurements of turbulent shear stresses in a Mach 3 compressible boundary layer were performed in order to investigate the effects of heat transfer on turbulence. Measurements were obtained by an x-probe in a flat plate, zero pressure gradient, two dimensional boundary layer in a wind tunnel with wall to freestream temperature ratios of 0.94 and 0.71. The measured shear stress distributions are found to be in good agreement with previous results, supporting the contention that the shear stress distribution is essentially independent of Mach number and heat transfer for Mach numbers from incompressible to hypersonic and wall to freestream temperature ratios of 0.4 to 1.0. It is also found that corrections for frequency response limitations of the electronic equipment are necessary to determine the correct shear stress distribution, particularly at the walls.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 17; July 197
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    Numerical modeling of two-dimensional confined flows (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A numerical model of two-dimensional confined flows is presented. The flow in the duct is partitioned into finite streams. The difference equations are then obtained by applying conservation principles directly to the individual streams. A listing of a computer code based on this approach in FORTRAN 4 language is presented. The code computes two dimensional compressible turbulent flows in ducts when the duct area along the flow is specified and the pressure gradient is unknown.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162115 , ME-MG79-1
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    Two-phase choked flow of cryogenic fluids in converging-diverging nozzles (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Data are presented for the two phase choked flow of three cryogenic fluids - nitrogen, methane, and hydrogen - in four converging-diverging nozzles. The data cover a range of inlet stagnation conditions, all single phase, from well below to well above the thermodynamic critical conditions. In almost all cases the nozzle throat conditions were two phase. The results indicate that the choked flow rates were not very sensitive to nozzle geometry. However, the axial pressure profiles, especially the throat pressure and the point of vaporization, were very sensitive to both nozzle geometry and operating conditions. A modified Henry-Fauske model correlated all the choked flow rate data to within + or - 10 percent. Neither the equilibrium model nor the Henry-Fauske model predicted throat pressures well over the whole range of data. Above the thermodynamic critical temperature the homogeneous equilibrium model was preferred for both flow rate and pressure ratio. The data of the three fluids could be normalized by the principle of corresponding states.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1484 , E-9659
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    Review and status of liquid-cooling technology for gas turbines (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A review was conducted of liquid-cooled turbine technology. Selected liquid-cooled systems and methods are presented along with an assessment of the current technology status and requirements. A comprehensive bibliography is presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-RP-1038 , E-9517 , AVRADCOM-TR-78-21
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    Full-coverage film cooling: 3-dimensional measurements of turbulence structure and prediction of recovery region hydrodynamics (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Hydrodynamic measurements were made with a triaxial hot-wire in the full-coverage region and the recovery region following an array of injection holes inclined downstream, at 30 degrees to the surface. The data were taken under isothermal conditions at ambient temperature and pressure for two blowing ratios: M = 0.9 and M = 0.4. Profiles of the three main velocity components and the six Reynolds stresses were obtained at several spanwise positions at each of the five locations down the test plate. A one-equation model of turbulence (using turbulent kinetic energy with an algebraic mixing length) was used in a two-dimensional computer program to predict the mean velocity and turbulent kinetic energy profiles in the recovery region. A new real-time hotwire scheme was developed to make measurements in the three-dimensional turbulent boundary layer over the full-coverage surface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3104 , SU-HMT-27
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    Titanium-alloy, metallic-fluid heat pipes for space service (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Reactivities of titanium limit its long-term terrestrial use for unprotected heat-pipe envelopes to about 870 K (1100 F). But this external thermochemical limitation disappears when considerations shift to space applications. In such hard-vacuum utilization much higher operating temperatures are possible. Primary restrictions in space environment result from vaporization, thermal creep, and internal compatibilities. Unfortunately, a respected head-pipe reference indicates that titanium is compatible only with cesium from the alkali-metal working-fluid family. This problem and others are subjects of the present paper which advocates titanium-alloy, metallic-fluid heat pipes for long-lived, weight-effective space service between 500 and 1300 K (440 and 1880 F).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-79132 , E-9974
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    Experiments on the large-scale structure of turbulence in the near-jet region (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The near region of an axisymmetric, turbulent jet was investigated. Turbulence quantities, as well as mean velocities, were measured between 3 and 23 diam away from the nozzle. The mean velocity profiles were similar over most of this distance, whereas the turbulence quantities were far from equilibrium conditions. Across the jet, the rate of large-scale turbulence varied considerably; however, a Strouhal number based on local velocity, the diameter of the jet, and the frequency of the large-scale turbulent oscillation remained relatively constant. The formation of the initial instability waves and the pairing of the vortices were examined. Turbulent fluctuations were observed only downstream of the pairing process.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78567 , A-7756
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    Exploratory investigation of the effect of porous surfaces on hypersonic turbulent boundary layers (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Four different test surfaces were studied to determine the effect of porous walls on the characteristics of a hypersonic turbulent flat-plate boundary layer. The investigation was an attempt to decrease the surface shear of the boundary layer by transmitting fluctuating pressure energy through the wall and absorbing it in a cavity beneath the wall. Pitot surveys were made at two locations, schlieren photographs of the boundary layer were taken, and hot-wire measurements in the flow above the boundary layer were made to determine whether the surfaces affected the turbulent boundary layer. Neither an increase nor a decrease in surface shear or boundary-layer growth was detected. Tabulations of the pitot data are included.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78791 , L-12271
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    Prediction of compliant wall drag reduction, part 2 (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A numerical model of turbulent boundary layer flows over compliant walls was investigated. The model is based on Burton's observation that outer flow structures in turbulent boundary layers produce large scale pressure fluctuations near the wall. The results of calculations indicate that certain small wavelength wall motions can have a significant effect upon the stability of turbulent boundary layers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3071
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    Fermi liquid viscosity in a finite geometry (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Forced flow of a Fermi liquid is studied for a cell geometry consisting of two planes with a separation on the order of mean free path. An approximate transport equation is used to derive an integral equation for the velocity profile, which is solved numerically. Results for the total flux through the cell, which determines the dissipation, are given as a function of the Knudsen number N (ratio of cell thickness to mean free path). Effects of specular reflection at the boundaries are considered. It is found that the dissipation has a minimum at N approximately equal to 1/2, and behaves linearly for N greater than or equal to 3. Implications for present experimentation are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-157835
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    Advanced Thermal control Flight Experiment (ATFE) (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A comprehensive description of the design and performance of the Advanced Thermal Control Flight Experiment (ATFE) is presented. The ATFE studied in a space environment for five years the steady state, transient ground and flight performance of (1) a thermal diode heat pipe, (2) a phase change material, and (3) a feedback controlled variable conductance heat pipe. It was found that all were flight worthy and highly reliable.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-152305 , BK028-1001
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    A group-velocity criterion for breakdown of vortex flow: An application to measured inlet profiles (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Vortex flows exhibiting breakdown in a slightly divergent duct were measured. The slowly varying vortex flow field downstream of the entrance and upstream of the breakdown region is obtained numerically by using the inviscid quasi-cylindrical approximation. In these calculations, the Faler and Lebovich's experimental data were used as the starting conditions at the entrance of the duct. The group velocity of wave propagation for the axisymmetric mode (n = 0) and the asymmetric modes (n = + or - 1 and n = + or - 2) are calculated for the entrance conditions. For the theoretically predicted slowly varying flow field downstream of the entrance, the wave characteristics of the n = 0 and n = + or - 1 modes are presented. It was concluded that the flows which subsequently undergo vortex breakdown are all predicted to be supercritical and stable to infinitesimal inviscid disturbances, including the axially symmetric as well as the nonsymmetric perturbations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78542 , A-7668
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    An examination of a group-velocity criterion for the breakdown of an idealized vortex flow (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The phenomenon of vortex breakdown is believed to be associated with a finite amplitude wave that has become trapped at the critical or breakdown location. The conditions at which the propagating waves become trapped at a certain axial location were examined by use of a group-velocity criterion implied by Landahl's general theory of wave trapping. An ideal vortex having constant vorticity and uniform axial velocity at the inlet of a slowly diverging duct was studied. The linear wave propagation analysis is applied to the base flow at several axial stations for several values of the ratio of swirl velocity to axial velocity at the inlet of the divergent duct, assuming a locally parallel flow. The dipsersion relations and hence the group velocities of both the symmetric (n = 0) and asymmetric modes (n = + or - 1) were investigated. The existence of a critical state in the flow (at which the group velocity vanishes), and its relationship to the stagnation point on the axis of the duct and to the occurrence of an irregular singularity in the equations governing wave propagation in the flow field are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78541 , A-7666
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    Experiments on the stability and transition of two-dimensional and three-dimensional boundary layers with suction (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The preliminary experimental development work directed towards the understanding of transition in boundary layers with suction is presented. The basic stability experiment was established and the facility was certified.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-157256
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    A study of response time of pitot pressure probes designed for rapid response and protection of transducer (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An eight orifice probe, designed to protect the transducer without the use of a baffle, was compared to a standard orifice-baffle probe in the small shock tube and in the expansion tube under normal run conditions. In both facilities, the response time of eight orifice probe was considerable better than the standard probe design.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-80091
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    Incorporation of coupled nonequilibrium chemistry into a two-dimensional nozzle code (SEAGULL) (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A two-dimensional multiple shock nozzle code (SEAGULL) was extended to include the effects of finite rate chemistry. The basic code that treats multiple shocks and contact surfaces was fully coupled with a generalized finite rate chemistry and vibrational energy exchange package. The modified code retains all of the original SEAGULL features plus the capability to treat chemical and vibrational nonequilibrium reactions. Any chemical and/or vibrational energy exchange mechanism can be handled as long as thermodynamic data and rate constants are available for all participating species.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3121
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    Some observations of flow structure in multiple jet mixing (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Results of hot wire measurements in an incompressible jet issuing from an array of rectangular lobes, equally spaced with their small dimensions in a line, both as a free jet, and as a confined jet, are presented. In the case of a multiple free jet, the flow field for downstream distance x greater than 60D (D = width of a lobe) resembles that of a jet exiting from a two-dimensional nozzle with its short dimension being the long dimension of the lobe. The field of turbulence is found to be nearly isotropic in the plane containing the small dimension of the lobes for x greater than 60D. In the case of a confined multiple jet, the flow field is observed to be nearly homogeneous and isotropic for x greater than 60D.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-166179 , SU-JIAA-TR-19 , Symp. on Turbulent Shear Flows; Jul 02, 1979 - Jul 04, 1979; London
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    Calculated global conditions for the unsteady Euler's flow equations (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: This paper considers the numerical solution of a fluid dynamical system with time-dependent oscillating boundaries. The problem detailed, a compressible and inviscid flow in a one-dimensional pipe with vibrating ends, is examined to develop techniques needed to solve the more complex unsteady flows in turbomachine cascades. The problem is shown to be mathematically ill-posed but by complementing the governing equations with energy conservation, a unique solution is obtained. An artificial damping term is introduced into the governing equations to improve the performance of the time-marching integration.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in computer methods for partial differential equations - III; Jun 20, 1979 - Jun 22, 1979; Bethlehem, PA
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    Application of the method of integral relations to unsteady fluid flow problems with shocks (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A mixed method using both the method of integral relations and the finite difference technique is developed for the solution of unsteady flow problems. The integral relations method is based upon a chosen interpolating function dependent only on the time domain. The resulting local semidiscrete finite element equations obtained are assembled into a global form. The spatial derivatives at the nodes are replaced by finite difference operators and the discretized nonlinear algebraic system is solved by an iterative scheme. Solutions are obtained for the one-dimensional gasdynamics equation, the one-dimensional wave equation and Burger's model of turbulence. Agreement with other numerical and analytical solutions is excellent for the gasdynamics problem and satisfactory for the Burger equation in cases of small viscous effects.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in computer methods for partial differential equations - III; Jun 20, 1979 - Jun 22, 1979; Bethlehem, PA
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    Explicit large time-step schemes for the shallow water equations (1979)
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    Publication Date: 2019-07-13
    Description: Modifications to explicit finite difference schemes for solving the shallow water equations for meteorological applications by increasing the time step for the fast gravity waves are analyzed. Terms associated with the gravity waves in the shallow water equations are treated on a coarser grid than those associated with the slow Rossby waves, which contain much more of the available energy and must be treated with higher accuracy, enabling a several-fold increase in time step without degrading the accuracy of the solution. The method is presented in Cartesian and spherical coordinates for a rotating earth, using generalized leapfrog, frozen coefficient, and Fourier filtering finite difference schemes. Computational results verify the numerical stability of the approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in computer methods for partial differential equations - III; Jun 20, 1979 - Jun 22, 1979; Bethlehem, PA
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  • 68
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    The solution of the three-dimensional viscous-compressible Navier-Stokes equations on a vector computer (1979)
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    Publication Date: 2019-07-13
    Description: The development of a vectorized computer code for the solution of the three-dimensional viscous-compressible Navier-Stokes equations is described. The code is applied on the CDC STAR-100 vector computer which is capable of achieving high result rates when a high degree of parallelism is present in the computations. The computational technique is an explicit time-split MacCormack predictor-corrector algorithm. Since a large volume of data is processed and virtual memory utilized, a data management scheme based on interleaving is used. The program has been applied to obtain the solution of the laminar supersonic flow about a family of three-dimensional corners. The equations of motion are expressed in a generalized form relative to a uniform rectangular computational domain. The metric coefficient and boundary conditions must be supplied for the corresponding physical domain. For calculations with 30,000 grid points, a computational rate of 0.00015 seconds per grid point per time step is observed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advances in computer methods for partial differential equations - III; Jun 20, 1979 - Jun 22, 1979; Bethlehem, PA
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  • 69
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    Heat pipe cooling of power processing magnetics (1979)
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    Publication Date: 2019-07-13
    Description: The constant demand for increased power and reduced mass has raised the internal temperature of conventionally cooled power magnetics toward the upper limit of acceptability. The conflicting demands of electrical isolation, mechanical integrity, and thermal conductivity preclude significant further advancements using conventional approaches. However, the size and mass of multikilowatt power processing systems may be further reduced by the incorporation of heat pipe cooling directly into the power magnetics. Additionally, by maintaining lower more constant temperatures, the life and reliability of the magnetic devices will be improved. A heat pipe cooled transformer and input filter have been developed for the 2.4 kW beam supply of a 30-cm ion thruster system. This development yielded a mass reduction of 40% (1.76 kg) and lower mean winding temperature (20 C lower). While these improvements are significant, preliminary designs predict even greater benefits to be realized at higher power. This paper presents the design details along with the results of thermal vacuum operation and the component performance in a 3 kW breadboard power processor.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-2082 , International Electric Propulsion Conference; Oct 30, 1979 - Nov 01, 1979; Princeton, NJ
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  • 70
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    Marangoni bubble motion in zero gravity (1979)
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    Publication Date: 2019-07-13
    Description: It is shown experimentally that the Marangoni phenomenon is a primary mechanism for the movement of a gas bubble in a nonisothermal liquid in a low-gravity environment. In such two-phase flow systems, local variations in bubble surface tension are caused by a temperature gradient in the liquid. Shearing stresses thus generated at the bubble surface lead to convection in both media, as a result of which the bubble begins to move. A mathematical model consisting of the Navier-Stokes equations and the thermal energy equations, along with the appropriate boundary conditions for both media, is proposed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Annual Meeting; Nov 25, 1979 - Nov 29, 1979; San Francisco, CA
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  • 71
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    Heat transfer through turbulent boundary layers - The effects of introduction of and recovery from convex curvature (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Measurements have been made of the heat transfer through a turbulent boundary layer on a convexly curved isothermal wall and on a flat plate following the curved section. Data were taken for one free-stream velocity and two different ratios of boundary layer thickness to radius of curvature delta/R = 0.051 and delta/R = 0.077. Only small differences were observed in the distribution of heat transfer rates for the two boundary layer thicknesses tested, although differences were noted in the temperature distributions within the boundary layer
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 79-WA/GT-10 , Winter Annual Meeting; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 72
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    Coolant tube curvature effects on film cooling as detected by infrared imagery (1979)
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    Publication Date: 2019-07-13
    Description: Reported herein are comparative thermal film cooling footprints observed by infrared imagery from straight, curved and looped coolant tube geometries. It was hypothesized that the difference in secondary flow and turbulence structure of flow through these three tubes should influence the mixing properties between the coolant and mainstream. The coolant was injected across an adiabatic plate through a hole angled at 30 deg to the surface in line with the free stream flow. The data cover a range of blowing rates from 0.37 to 1.25 (mass flow per unit area of coolant divided by free stream). Average temperature difference between coolant and tunnel air was 25 C. Data comparisons confirmed that coolant tube curvature significantly influences film cooling effectiveness.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 79-WA/GT-7 , Winter Annual Meeting; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 73
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    Evaluation of the time dependent surface shear stress in turbulent flows (1979)
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    Publication Date: 2019-07-13
    Description: The time dependent surface shear stress has been evaluated using surface heat transfer measurements. For fully developed turbulent pipe and open channel water flows, and incompressible and compressible turbulent boundary layer air flows the measurements indicate the absolute magnitude of the surface shear stress fluctuations will be greater than two times the mean values. The root-mean-square shear stress fluctuations were of the order of 0.2 to 0.4 times the mean surface shear values. Due to these large surface shear stress fluctuations and the nonlinear relation between heat transfer and shear stress, a special technique has been developed to evaluate the measurements. It was found that the non-linear averaging errors for a hot film-surface shear stress gauge in a fully developed pipe flow was of the order of 10 percent at low velocities. A hot wire-surface shear stress gauge was employed for measurements of turbulent boundary layers in air.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 79-WA/FE-17 , Winter Annual Meeting; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 74
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    On the question of instabilities upstream of cylindrical bodies (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: In an attempt to understand the unsteady vortical phenomena in perturbed stagnation regions of cylindrical bodies, a critical review of the theoretical and experimental evidence was made. Current theory is revealed to be incomplete, incorrect, or inapplicable to the phenomena observed experimentally. The formalistic approach via the principle of exchange of instabilities should most likely be replaced by a forced-disturbance approach. Also, many false conclusions were reached by ignoring that treatment of the base and perturbed flows in Hiemenz coordinate eta is asymptotic in nature. Almost surely the techniques of matched asymptotic expansions are expected to be used to capture correctly the diffusive and vorticity amplifying processes of the disturbances regarding the mean-flow boundary layer and outer potential field as eta and y/diameter approach infinity. The serious uncertainties in the experiments are discussed in detail.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3231 , R79-3
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  • 75
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    Unsteady flow and dynamic response analyses for helicopter rotor blades (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Research is presented on helicopter rotor blade vibration and on two and three dimensional analyses of unsteady incompressible viscous flow past oscillating helicopter rotor blades. A summary is presented of the two international research collaborations which resulted from the NASA project: the collaboration under the auspices of NATO between the University of Wisconsin-Milwaukee, University of Brussels, Belgium and the Aerodynamics Research Establishment in Goettingen, West Germany, and the collaboration under the auspices of the National Science Foundation between UWM and the University of Hamburg and the Ship Research Establishment in Hamburg, West Germany. A summary is given of the benefits from the NASA project to UWM, the College of Engineering and Applied Science, and the participants on the project.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-159190
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  • 76
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    Measurements of flow phenomena induced by suction through perforated and partially plugged surfaces (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Efforts were directed towards completing construction of the windtunnel test section, assembling instrumentation, programming the data acquisition and reduction system, adjusting the streamwise pressure gradient of the test section, calibrating the hot-wire anemometer probe, and constructing and testing a smoke generator. The test section was installed in the wind tunnel and is completely operational. The streamwise pressure gradient was adjusted to be nominally zero at a free-stream velocity of 3.05 m/s (10 ft/s). This was accomplished by adjusting the upper wall of the test section to be slightly divergent. The change in static pressure between any two streamwise locations in the test section was less than one percent of the free-stream dynamic pressure. A suitable means was found for accurately calibrating the hot-wire probe which is used to measure boundary-layer velocity profiles and fluctuating velocities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-158001
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    Condensation on a noncollapsing vapor bubble in a subcooled liquid (1979)
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    Publication Date: 2019-07-13
    Description: An experimental procedure is presented by which an estimate can be made of the condensation coefficient on a noncollapsing stationary vapor bubble in subcooled liquid nitrogen. The present experimental study utilizes film boiling from a thin wire to generate vapor bubbles which remain fixed to the wire at their base. A balance was established between the evaporation in the thin annular region along the wire and the condensation in the vapor bubbles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: National Heat Transfer Conference; Aug 05, 1979 - Aug 08, 1979; San Diego, CA
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  • 78
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    A prediction method for velocity and temperature profiles in a two-dimensional nominally steady turbulent boundary layer (1979)
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    Publication Date: 2019-07-13
    Description: This paper describes a recently developed boundary-layer prediction method for a variable property compressible flow, in which heat transfer takes place primarily by forced convection and for which the mainstream Mach number is small. The leading order terms, in asymptotic expansions for large Reynolds numbers, are obtained for the mean velocity and temperature distribution in both the inner and outer layer of the turbulent boundary layer. Closure in the inner layer is achieved using an analytical model for the mean profiles which is based on the observed coherent structure of the time-dependent inner layer flow. For the outer layer, simple eddy viscosity and conductivity models are developed without recourse to the Reynolds analogy. In the prediction method a numerical solution of the outer layer equations is matched to the analytical inner layer profiles as the computation procedes downstream. Calculations are presented for a range of adverse and favorable pressure gradient flows and the predicted results compare well with existing data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulent boundary layers: Forced, incompressible, non-reacting; Joint Applied Mechanics, Fluids Engineering and Bioengineering Conference; Jun 18, 1979 - Jun 20, 1979; Niagara Falls, NY
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    Preferential spectral transport by irrotational straining (1979)
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    Publication Date: 2019-07-13
    Description: The addition of an extra term to the conventional approximate transport equation for the turbulence energy dissipation rate is recommended. The term may be viewed as emphasizing the role of irrotational deformations in promoting energy transfer across the spectrum or, equivalently, as augmenting the influence of normal strains. Calculations including the new term are reported for the plane and round jet and for several turbulent boundary layers. In the cases considered the addition of the new term significantly improves agreement with experimental data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulent boundary layers: Forced, incompressible, non-reacting; Joint Applied Mechanics, Fluids Engineering and Bioengineering Conference; Jun 18, 1979 - Jun 20, 1979; Niagara Falls, NY
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  • 80
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    Flow friction of the turbulent coolant flow in cryogenic porous cables (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Considered are cryogenic power transmission cables with porous cores. Calculations of the turbulent coolant flow with injection or suction through the porous wall are presented within the framework of a two-layer model. Universal velocity profiles were obtained for the viscous sublayer and flow core. Integrating the velocity profile, the law of flow friction in the pipe with injection has been derived for the case when there is a tangential injection velocity component. The effect of tangential velocity on the relative law of flow friction is analyzed. The applicability of the Prandtl model to the problem under study is discussed. It is shown that the error due to the acceptance of the model increases with the injection parameter and at lower Reynolds numbers; under these circumstances, the influence of convective terms in the turbulent energy equation on the mechanism of turbulent transport should be taken into account.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-79052 , DOE/NASA/0207-79/1 , Intern. Congr. on Refrigeration; Sep 23, 1979 - Sep 29, 1979; Venice; Italy
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  • 81
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    On the viscous-inviscid flow interaction in the vicinity of a laminar separation bubble (1979)
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    Publication Date: 2019-07-13
    Description: An incompressible, two-dimensional, thin separation bubble is treated as an obstacle to the potential flow that perturbs and adjusts the original inviscid flow. The knowledge of the perturbed velocity allows a complete flow description in vicinity of the bubble. Suitable differential equations and boundary conditions are developed for three distinct regions, namely, a potential region, a parabolic viscous layer, and a viscous, slow recirculating region. With modified boundary conditions the boundary layer equations are regularly integrated through the separation region. Conclusions are also made on the wall stress and the position of zero velocity and zero vorticity lines.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1478 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 82
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    Large eddy simulation - A predictive approach to turbulent flow computation (1979)
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    Publication Date: 2019-07-13
    Description: The filtering approach (Leonard, 1974) to large eddy simulation is described. Large eddy simulation is then surveyed with reference to subgrid scale models, numerical methods, channel flow, and free shear flows. It is concluded that the premise of LES (i.e., that the small eddies are much easier to model than the large ones) seems to be borne out by computational experience to date. The greatest obstacle in LES at present is the lack of computer power which effectively denies the ability to simulate all the significant eddies in flows of interest.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1471 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 83
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    Analysis and computation of viscous subsonic primary and secondary flows (1979)
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    Publication Date: 2019-07-13
    Description: A new approximate flow analysis, designed to enable numerical solution as an initial value problem, is developed for a wide class of viscous subsonic flows at high Reynolds number and in straight or smoothly curved three-dimensional flow geometries. The analysis is coordinate-independent and corrects an a priori known inviscid primary flow for viscous and thermal effects, secondary flows, total pressure distortion, internal flow blockage and pressure drop. Computed results include laminar solutions for three-dimensional boundary layer flow, fully viscous flow in circular arc ducts, and also flow in a curved duct shaped like a turbine blade passage.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1453 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 84
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    Boundary conditions for implicit solutions to the compressible Navier-Stokes equations in finite computational domains (1979)
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    Publication Date: 2019-07-13
    Description: The admissible boundary conditions for the unsteady Navier-Stokes equations are insufficient to determine completely the flow variables at grid points on the boundaries of a finite computational domain. A general method is presented in which the boundary conditions are supplemented by conservatively differenced forms of the flow equations. For implicit algorithms, the method provides a fully implicit coupling between boundary and interior points. Implicit boundary-point computation schemes are given for most types of flow boundary encountered in internal and external flow problems. Convergence to steady state is generally faster than with locally explicit boundary-point schemes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1447 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 85
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    Application of a velocity-split Navier-Stokes solution technique to external flow problems (1979)
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    Publication Date: 2019-07-13
    Description: A method for solving the Navier-Stokes equations based on splitting the velocity vector into its rotational and irrotational parts has recently been applied successfully to internal flow computations. In this paper, the applicability of the method to external flows is examined by studying two model problems; laminar incompressible flow over semiinfinite and finite flat plates. For these problems the procedure accurately reproduces the known solutions and is computationally very efficient even at high Reynolds numbers. Computational aspects of the method are discussed along with the possibility of using the procedure to retrofit a viscous capability into existing transonic potential flow codes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1449 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 86
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    Low-Reynolds-number turbulent boundary layers (1979)
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    Publication Date: 2019-07-13
    Description: A test facility operating at substantially reduced pressures is described and shown to be suitable when used with an open-circuit turbulent boundary layer wind tunnel. The facility is capable of producing flows with momentum Reynolds number in the range 200-10,000 by varying the ambient pressure. At low-Reynolds-number flows the pressure is low enough to allow the tunnel to operate with large values of freestream speed. The tunnel's reliability is verified by examining flows where momentum Reynolds number is greater than 1200. The results skin friction coefficients, wake parameters, and basic velocity profiles - consistently agreed with well-established data. For momentum Reynolds number from 600 through 1200 the resulting data indicate that the 'universal velocity profile' is accurate and correctly describes the mean flow properties. For Reynolds number from 425 through 600, the viscous sublayer in this range can no longer maintain its characteristic size.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulent boundary layers: Forced, incompressible, non-reacting; Joint Applied Mechanics, Fluids Engineering and Bioengineering Conference; Jun 18, 1979 - Jun 20, 1979; Niagara Falls, NY
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  • 87
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    Finite element methodology for transient conduction/forced-convection thermal analysis (1979)
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    Publication Date: 2019-07-13
    Description: Finite element methodology for steady state thermal analysis of convectively cooled structures has been extended for transient analysis. The finite elements are based on representing the fluid passages by fluid bulk-temperature nodes and fluid-solid interface nodes. The formulation of the finite element equations for a typical flow passage is based on the weighted residual method with upwind weighting functions. Computer implementation of the convective finite element methodology using explicit and implicit time integration algorithms is described. Accuracy and efficiency of the methodology is evaluated by comparisons with analytical solutions and finite-difference lumped-parameter analyses. The comparative analyses demonstrate that finite element conduction/conduction methodology may be used to predict transient temperatures with an accuracy equal or superior to the lumped-parameter finite-difference method.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1100 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Jun 04, 1979 - Jun 06, 1979; Orlando, FL
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  • 88
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    A two phase Mach number description of the equilibrium flow of nitrogen in ducts (1979)
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    Publication Date: 2019-07-13
    Description: Some additional thermodynamic properties of the usual two-phase form which is linear in the moisture fraction are derived which are useful in the analysis of many kinds of duct flow. The method used is based on knowledge of the vapor pressure and Gibbs function as functions of temperature. With these, additional two-phase functions linear in moisture fraction are generated, which ultimately reveal that the squared ratio of mixture specific volume to mixture sound speed depends on liquid mass fraction and temperature in the same manner as do many weighted mean two-phase properties. This leads to a simple method of calculating two-phase Mach numbers for various duct flows. The matching of one- and two-phase flows at a saturated vapor point with discontinuous Mach number is also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1051 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Jun 04, 1979 - Jun 06, 1979; Orlando, FL
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  • 89
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    LDEF transverse flat plate heat pipe experiment /S1005/ (1979)
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    Publication Date: 2019-07-13
    Description: The paper describes the Transverse Flat Plate Heat Pipe Experiment. A transverse flat plate heat pipe is a thermal control device that serves the dual function of temperature control and mounting base for electronic equipment. In its ultimate application, the pipe would be a lightweight structure member that could be configured in a platform or enclosure and provide temperature control for large space structures, flight experiments, equipment, etc. The objective of the LDEF flight experiment is to evaluate the zero-g performance of a number of transverse flat plate heat pipe modules. Performance will include: (1) the pipes transport capability, (2) temperature drop, and (3) ability to maintain temperature over varying duty cycles and environments. Performance degradation, if any, will be monitored over the length of the LDEF mission. This information is necessary if heat pipes are to be considered for system designs where they offer benefits not available with other thermal control techniques, such as minimum weight penalty, long-life heat pipe/structural members.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1077 , American Institute of Aeronautics and Astronautics, Thermophysics Conference; Jun 04, 1979 - Jun 06, 1979; Orlando, FL
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  • 90
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    A study of viscous cross-flow effects on circular cylinders at high Reynolds numbers (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Results of experimental studies on viscous cross-flow over circular cylinders for Reynolds numbers from 0.15 x 10 to the 6th to 10.9 x 10 to the 6th at Mach numbers of less than 0.3 are presented and compared with previous work where possible. Results presented include the variation of static cross-flow drag coefficients with both Reynolds number and ratio of surface roughness to model diameter, the variation of Strouhal number with Reynolds number and the dynamic variation of surface static pressure coefficients with both angular position around the cylinder and Reynolds number. The effects of end-plates on flow around two-dimensional bluff-bodies and of tunnel blockage on drag measurements are also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1477 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 91
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    Multi-level adaptive computations in fluid dynamics (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The multi-level adaptive technique (MLAT) is a general strategy of solving continuous problems by cycling between coarser and finer levels of discretization. It provides very fast solvers together with adaptive, nearly optimal discretization schemes to general boundary-value problems in general domains. Here the state of the art is surveyed, emphasizing steady-state fluid dynamics applications, from slow viscous flows to transonic ones. Various new techniques are briefly discussed, including distributive relaxation schemes, the treatment of evolution problems, the combined use of upstream and central differencing, local truncation extrapolations, and other 'super-solver' techniques.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1455 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 92
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    An implicit factored scheme for the compressible Navier-Stokes equations. II - The numerical ODE connection (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An attempt is made to establish a connection between linear multistep methods for applications to ordinary differential equations and their extension (by approximate factorization) to alternating direction implicit methods for partial differential equations. An earlier implicit factored scheme for the compressible Navier-Stokes equations is generalized by innovations that (1) increase the class of temporal difference schemes to include all linear multistep methods, (2) optimize the class of unconditionally stable factored schemes by a new choice of unknown variable, and (3) improve the computational efficiency by the introduction of quasi-one-leg methods.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 79-1446 , In: Computational Fluid Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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  • 93
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    Secondary instability in boundary-layer flows (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The stability of a secondary Tollmien-Schlichting wave, whose wavenumber and frequency are nearly one half those of a fundamental Tollmien-Schlichting instability wave is analyzed using the method of multiple scales. Under these conditions, the fundamental wave acts as a parametric exciter for the secondary wave. The results show that the amplitude of the fundamental wave must exceed a critical value to trigger this parametric instability. This value is proportional to a detuning parameter which is the real part of k - 2K, where k and K are the wavenumbers of the fundamental and its subharmonic, respectively. For Blasius flow, the critical amplitude is approximately 29% of the mean flow, and hence many other secondary instabilities take place before this parametric instability becomes significant. For other flows where the detuning parameter is small, such as free-shear layer flows, the critical amplitude can be small, thus the parametric instability might play a greater role.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AD-A074792 , Physics of Fluids; 22; May 1979
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  • 94
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    Filtering of non-linear instabilities (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: For Courant numbers larger than one and cell Reynolds numbers larger than two, oscillations and in some cases instabilities are typically found with implicit numerical solutions of the fluid dynamics equations. This behavior has sometimes been associated with the loss of diagonal dominance of the coefficient matrix. It is shown here that these problems can in fact be related to the choice of the spatial differences, with the resulting instability related to aliasing or nonlinear interaction. Appropriate 'filtering' can reduce the intensity of these oscillations and in some cases possibly eliminate the instability. These filtering procedures are equivalent to a weighted average of conservation and non-conservation differencing. The entire spectrum of filtered equations retains a three-point character as well as second-order spatial accuracy. Burgers equation has been considered as a model. Several filters are examined in detail, and smooth solutions have been obtained for extremely large cell Reynolds numbers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Engineering Mathematics; 13; Apr. 197
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  • 95
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    Dynamics of liquid films and thin jets (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The theory of liquid films and thin jets as one- and two-dimensional continuums is examined. The equations of motion have led to solutions for the characteristic speeds of wave propagation for the parameters characterizing the shape. The formal analogy with a compressible fluid indicates the possibility of shock wave generation in films and jets and the formal analogy to the theory of threads and membranes leads to the discovery of some new dynamic effects. The theory is illustrated by examples.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: SIAM Journal on Applied Mathematics; 37; Oct. 197
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  • 96
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    Screening of liquids for thermocapillary bubble movement (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Ground-based methods for pretesting qualitatively the thermocapillary movement of gas bubbles in a liquid to be used in space processing are discussed. Theoretical considerations are shown to require the use of a thin, enclosed, horizontal liquid film in order that the bubbles move faster than the bulk convection of the liquid, with insulating boundaries to prevent the onset of instabilities. Experimental realizations of horizontal cells in which to test the thermocapillary movement of bubbles in sheets of molten glass heated from below and organic melts in tubes heated from both ends are briefly described and the results of experiments are indicated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 17; Sept
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  • 97
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    Radiative and free convective heat transfer from a containerless sphere (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A mathematical model is derived for heat loss due to radiation and free convection for a small copper sphere (approximately 0.3 to 0.4 cm diameter) cooled by a helium-argon gas mixture. A FORTRAN program written to simplify calculations and extend the range of applicability to experimentation is presented. Pressures used were less than 400 torr, and resulting temperatures ranged from 500 to 4600 K. Comparison of results for initial cooling by the gas mixture with experimental data showed a 5 percent error for temperature values and a 2.7 percent error for the temperature difference caused by the cooling. Results indicate that the accuracy could be increased significantly by using better estimates for thermal conductivities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78249
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  • 98
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    Flow on Magnetizable Particles in Turbulent Air Streams (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The flow of magnetizable particles in a turbulent air stream in the presence of an imposed magnetic field and the phenomenon of drag reduction produced by the introduction of particles in turbulent boundary layer are investigated. The nature of the particle magnetic force is discussed and the inherent difference between electric and magnetic precipitation is considered. The incorporation of turbulent diffusion theory with an imposed magnetic migration process both with and without inertia effects is examined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162418
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  • 99
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    An experimental investigation to determine the effect of window cooling by mass injection for the Shuttle Infrared Leeside Temperature Sensing (SILTS) experiment (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of mass injection on the shuttle infrared leeside temperature sensing (SILTS) pod window surfaces in reducing window heating and minimizing window lens radiation during the reentry data taking period is investigated. Heat transfer coefficients on and around the simulated windows and window cavities are determined. Heat transfer rates and window coolant flow rates are reported for the SILTS configuration. A comparison of two windows' geometries and their effects on the heat transfer rate is discussed and oil flow photographs are presented to indicate how mass injection affects the flow field near the SILTS window.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-80170
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  • 100
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    Effects of truncation in modal representations of thermal convection (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The Galerkin (including single-mode and Lorenz) equations were examined for convection in a sphere to determine which physical processes are neglected when the equations of motion are truncated too severely. The conclusions were tested by calculating solutions to the equations of motion for different values of the Rayleigh number and for different values of the limit of the horizontal spatial resolution. It was shown that the transitions from steady state to periodic, then to aperiodic convection depend not only on the Rayleigh number but also very strongly on the horizontal resolution. One of the effects of truncation is to enhance the high wavenumber end of the kinetic energy and thermal variance spectra. The numerical examples indicate that as long as the kinetic energy spectrum decreases with wavenumber, a truncation gives a qualitatively correct solution.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-162251 , CRSR-730
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