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  • Other Sources  (225)
  • FLUID MECHANICS AND HEAT TRANSFER  (225)
  • 1980-1984  (225)
  • 1981  (225)
  • 1
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    Effect of shear stress on cell cultures and other reactor problems (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Anchorage dependent cell cultures in fluidized beds are tested. Feasibility calculations indicate the allowed parameters and estimate the shear stresses therein. In addition, the diffusion equation with first order reaction is solved for the spherical shell (double bubble) reactor with various constraints.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 19 p
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  • 2
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    Capillary priming characteristics of a dual passage heat pipe in zero-g (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Technical improvements of a long life heat rejection system, suitable for long duration high power missions, that can be constructed and deployed in orbit is discussed. A mathematical model is formulated and a computer program developed which describes the transient priming characteristics of a dual passage heat pipe. An experimental test package is described for flight in the KC-135 Zero-g Aircraft, to be used to verify the modeling predictions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 50 p
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  • 3
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    Two-phase flow and heat transfer under low gravity (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Spacelab experiment to investigate two-phase flow patterns under gravity uses a water-air mixture experiment. Air and water are circulated through the system. The quality or the mixture or air-water is controlled. Photographs of the test section are made and at the same time pressure drop across the test section is measured. The data establishes a flow regime map under reduced gravity conditions with corresponding pressure drop correlations. The test section is also equipped with an electrical resistance heater in order to allow a flow boiling experiment to be carried out using Freon II. High-speed photographs of the test section are used to determine flow patterns. The temperature gradient and pressure drop along the duct can be measured. Thus, quality change can be measured, and heat transfer calculated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 43-57
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  • 4
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    Effects of spacecraft motions on fluids experiments (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The equations of motion governing an incompressible fluid contained in an orbiting laboratory were examined to isolate various fictitious forces and their relative influence on the fluid. The forces are divided into those arising from the orbital motions and those arising from small local motions of the spacecraft about its center of mass. The latter dominate the nonrotating experiments. Both are important for rotating experiments. A brief discussion of the onset of time-dependence and violent instability in earth-based rotating and processing systems is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 96-102
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  • 5
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    Convection in fluids at reduced gravity (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Natural convection is not always harmful and, therefore, to be avoided. In some situations it may be desirable to have fluid flows in space processes, e.g., to stir the fluid phase for mixing and cooling or to help maintain concentration gradients. In may event, it is important to know the extent and nature of convection in space and the factors on which it depends, in order either to minimize the effects to convection, or to utilize the convection to advantage. The information needed to assess both conventional and unstable convection includes: (1) the magnitude and direction of accelerations; (2) geometric configuration; (3) imposed boundary conditions; and (4) material properties.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Spacecraft Dyn. as Related to Lab. Expt. in Space; p 69-95
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  • 6
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    Geophysical fluid dynamics (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Systematic scaling or dimensional analysis reveals that certain scales of geophysical fluid flows (such as stellar, ocean, and planetary atmosphere circulations) can be accurately modeled in the laboratory using a procedure which differs from conventional engineering modeling. Rather than building a model to obtain numbers for a specific design problem, the relative effects of the significant forces are systematically varied in an attempt to deepen understanding of the effects of these forces. Topics covered include: (1) modeling a large-scale planetary atmospheric flow in a rotating cylindrical annulus; (2) achieving a radial dielectric body force; (3) spherical geophysical fluid dynamics experiments for Spacelab flights; (4) measuring flow and temperature; and (5) the possible effect of rotational or precessional disturbances on the flow in the rotating spherical containers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Spacecraft Dyn. as Related to Lab. Expt. in Space; p 25-31
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  • 7
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    Analysis of low-g heat transfer for a cryogenic oxygen pressurization heater (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: After the external tank separates from the Orbiter about 2000 pounds of residual liquid oxygen remain in the main propulsion system lines. The pressurization of liquid oxygen from a subcritical to a supercritical state by the use of the heaters of the PRSA tanks while in a low-g environment is investigated. The performance of the heaters while bringing the state of the substance from the subcritical state to the supercritical one is studied, with particular emphasis on the time the pressurization process takes, and the temperature of the heater as the process proceeds.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 38 p
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  • 8
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    Vibration of a liquid with a free surface in a spinning spherical tank (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The problem of forced fluid vibrations in a partially filled spinning spherical tank is solved numerically by using the finite element method. The governing equations include Coriolis acceleration and spatially homogeneous vorticity. An exponential instability is detected in the present simulation for fill ratios below 0.5 and centrifugal acceleration to thrust ratios less than 1.7. This fictitious 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: Journal of Sound and Vibration; 76; May 8
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  • 9
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    Heat transfer in cooled porous region with curved boundary (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Heat transfer characteristics are analyzed for a cooled two-dimensional porous medium having a curved boundary. A general analytical procedure is given in combination with a numerical conformal mapping method used to transform the porous region into an upper half plane. To illustrate the method, results are evaluated for a cosine shaped boundary subjected to uniform external heating. The results show the effects of coolant starvation in the thick regions of the medium, and the extent that internal heat conduction causes the heated surface to have a more uniform temperature.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 10
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    Interactive method for computation of viscous flow with recirculation (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An interactive method is proposed for the solution of two-dimensional, laminar flow fields with identifiable regions of recirculation, such as the shear-layer-driven cavity flow. The method treats the flow field as composed of two regions, with an appropriate mathematical model adopted for each region. The shear layer is computed by the compressible boundary layer equations, and the slowly recirculating flow by the incompressible Navier-Stokes equations. The flow field is solved iteratively by matching the local solutions in the two regions. For this purpose a new matching method utilizing an overlap between the two computational regions is developed, and shown to be most satisfactory. Matching of the two velocity components, as well as the change in velocity with respect to depth is amply accomplished using the present approach, and the stagnation points corresponding to separation and reattachment of the dividing streamline are computed as part of the interactive solution. The interactive method is applied to the test problem of a shear layer driven cavity. The computational results are used to show the validity and applicability of the present approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 40; Apr. 198
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  • 11
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    Large-eddy simulation of the shear-free turbulent boundary layer (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The shear-free turbulent boundary layer is calculated by the large-eddy simulation technique. The filtered Navier-Stokes equations are used; the method of integration employs Fourier expansions in the homogeneous directions and finite differences in the cross-stream direction. Results indicate that the simulation is capable of predicting the primary Reynolds-number effects.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 103; Feb. 198
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  • 12
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    A molecular model for ice nucleation and growth, attachment 1 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The quantum mechanical technique is used to study ionic, configurational, and impurity defects in the ice surface. In addition to static calculations of the energetics of the water monomer-ice surface interactions, molecular dynamics studies were initiated. The calculations of the monomer-ice surface interaction, molecular dynamics studies were initiated. The calculations of monomer-ice surface interactions indicate that many adsorption sites exist on the ice surfaces and that the barriers between bonding sites are relatively low. Bonding on the prism face of ice is preferentially above lattice sites.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: A Mol. Model for Ice Nucleation and Growth; 27 p
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  • 13
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    A molecular model for ice nucleation and growth, attachment 2 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The central field empirical pair potential model is applied to studying the effects of kinks, ledges, and vacancies on the absorption of water molecules from the vapor. Molecular dynamics simulations indicate that cluster and/or surface modes play a primary role in the absorption process, the flexibility of the hydrogen bond serves to decrease the energy required for structural interconversion, and the rapid distribution of added energy in a hydrogen bonded system lead to aggregate stability which greatly exceeds that predicted by static energy calculations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: A Mol. Model for Ice Nucleation and Growth; 22 p
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  • 14
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    Report of the panel on fluid dynamics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Areas of investigation in fluid dynamics, recommended experiments, and use of the facility for theory evaluation are discussed. Tunnel flow quality and calibration of the NTF are considered. Recent technological advances affecting tunnel design are surveyed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: High Reynolds Number Res. - 1980; p 169-195
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  • 15
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    Flux vector splitting of the inviscid gasdynamic equations with application to finite-difference methods (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The conservation-law form of the inviscid gasdynamic equations has the remarkable property that the nonlinear flux vectors are homogeneous functions of degree one. This property readily permits the splitting of flux vectors into subvectors by similarity transformations so that each subvector has associated with it a specified eigenvalue spectrum. As a consequence of flux vector splitting, new explicit and implicit dissipative finite-difference schemes are developed for first-order hyperbolic systems of equations. Appropriate one-sided spatial differences for each split flux vector are used throughout the computational field even if the flow is locally subsonic. The results of some preliminary numerical computations are included.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 40; Apr. 198
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  • 16
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    Spectral energy transfer for inhomogeneous turbulence (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is noted that several terms in the two-point spectral equation for homogeneous turbulence can be interpreted as spectral-transfer terms; that is, they represent the net rate of energy transfer into a wavenumber region from all other wavenumbers. This holds for terms associated with both turbulence and self-interaction and interaction between turbulence and mean gradients. It is not seen as obvious, however, that similar interpretations apply when the turbulence is not homogeneous. In particular, one might question the interpretation for the terms associated with turbulence self-interaction because the condition of homegeneity is generally used in making the interpretation. It is the purpose here to consider whether terms interpretable as transfer terms exist in the equations for inhomogeneous turbulence. It is found that certain terms in the two-point spectral equation can be interpreted as transfer terms.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 24; Oct. 198
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  • 17
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    Distorted turbulence in axisymmetric flow (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A solution to the rapid-distortion theory for small-scale turbulence in flow round an axisymmetric obstacle is derived. General formulae for velocity covariances and Eulerian time scales are obtained and are evaluated for the particular case of flow round a sphere. The large-scale limit for this flow is also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Quarterly Journal of Mechanics and Applied Mathematics; 34; Nov. 198
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  • 18
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    Multivalued velocity field model of turbulence (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The considered study is based on new theoretical concepts regarding a post-instability model of a fluid discussed by Zak (1980). The model permits the completion of the governing equations of turbulence by introducing multivalued fields of velocities. Attention is given to the mechanism of energy dissipation, the characteristic wave propagation, a simplified model, the formation of turbulence around stagnation points, the formulation of boundary conditions, and the mechanism of turbulence formation. The mechanism of turbulence formation can be understood as propagation of initial discontinuities from the boundaries into a flow with the characteristic velocity which is defined by the normal (to the boundary) velocity components. These components emerge at the boundary as a result of jumps in the tangential components due to the continuity equation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Mechanics Research Communications; 8; 2, 19; 1981
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  • 19
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    On the mixing of a rectangular jet (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Hot-wire measurements in an incompressible rectangular jet, issuing into a quiet environment at ambient conditions, are presented. A blow-down-type air supply system was used to provide the airflow to a cylindrical settling chamber 1.75 m in length and 0.6 m in diameter. The measurements were made with constant-temperature anemometers in conjunction with linearizers. The two signals from the linearizers were sent through a sum and difference unit which was calibrated from dc to 100 kHz. The distributions of mean velocity and the turbulence shear stresses were measured in the two central planes of the jet stations up to 115 widths downstream of the nozzle exit. Three distinct regions characterized the jet flow field: a potential core origin, a two-dimensional-type region, and an axisymmetric type region. The onset of the second region appeared to be at a location where the shear layers separated by the short dimension of the nozzle meet; and the third region occurred at a downstream location where the two shear layers from the short edges of the nozzle meet. In the central plane, similarity was found both in the mean velocity and shear stress profiles beyond 30 widths downstream of the nozzle exit; profiles of rms velocity showed similarity in the second, but not the third region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 107; June 198
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  • 20
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    Analysis of capacitive heat exchangers, part 1 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Governing equations are developed for a simple capacitive heat exchanger. This type of heat exchanger consists of hot spherical particles falling through an ascending cold gas stream. The assumptions made in deriving the continuity, momentum and energy equations are clearly stated. The analysis yields a system of first order, ordinary, nonlinear equations which form a complex boundary value problem. The method of solution is presented together with a comparison between the performance of capacitive heat exchangers and conventional counter flow ones.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 207-221
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  • 21
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    Role of coherent structures in turbulent shear flows (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A definition for the large-scale coherent structure is presented, and the nature and role of coherent structures in turbulent shear flows are examined. The equations governing the coherent motions and the experimental considerations as well as constraints in the investigations of coherent structures in wall-bounded and free turbulent shear flows are discussed. Results from a few of our recent and on-going studies of coherent structures in excited and unexcited free turbulent shear flows are reviewed. These results show that coherent structures are dominant in transport in the early stages of their formation, but not in the self-preserving regions of turbulent shear flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: vol. 4; Aug. 198
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  • 22
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    Laminar free convection boundary layer heat transfer over non-isothermal surface (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Accurate heat transfer results are provided for the case of nonisothermal objects. A steady, laminar, free convection boundary layer flow over two-dimensional or rotationally symmetrical bodies of nonuniform surface temperature situated in an ambient fluid of undisturbed temperature is considered analytically. The surface heat flux is given in terms of the Nusselt number and wall derivatives of universal functions for Prandtl numbers of 0.72 and 100 are provided. The method is shown to be valid up to a temperature/radius ratio of 130 deg.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 23
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    A viscous-inviscid interaction model of jet entrainment (1981)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: A viscous-inviscid interaction model for predicting jet entrainment effects on axisymmetric, nozzle afterbodies at subsonic speeds is presented. The model is based on a displacement thickness correction to the inviscid jet boundary that accounts for mixing-induced streamline deflections in the inviscid region. The displacement correction is shown to be related to the local mass entrainment rate and, for thin mixing layers, the model is shown to be analogous to displacement models used in conventional boundary-layer interaction theory. A method is presented for computing the entrainment rate by an overlaid mixing layer model that accounts for the nonsimilar behavior and pressure gradients occurring in the near field region. An iterative scheme for coupling the model to analyses for the external inviscid flow, the external boundary layer, and the inviscid jet exhaust is also given. Results are presented that illustrate the qualitative behavior of the entrainment interaction under various flow conditions and that demonstrate the validity of the model by comparisons with experiment.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Computation of Viscous-Inviscid Interactions; 15 p
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  • 24
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    Numerical solution of the Euler equations by finite volume methods using Runge Kutta time stepping schemes (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A new combination of a finite volume discretization in conjunction with carefully designed dissipative terms of third order, and a Runge Kutta time stepping scheme, is shown to yield an effective method for solving the Euler equations in arbitrary geometric domains. The method has been used to determine the steady transonic flow past an airfoil using an O mesh. Convergence to a steady state is accelerated by the use of a variable time step determined by the local Courant member, and the introduction of a forcing term proportional to the difference between the local total enthalpy and its free stream value.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 81-1259
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  • 25
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    A numerical simulation of the dispersal of aerial sprays (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A computer program was developed to predict the trajectory, ground deposition, and drift of liquid sprays injected into the wake of an agricultural aircraft in ground effect. The program uses a horseshoe vortex wake model and includes the effects of liquid droplet evaporation, crosswind, the propeller slipstream, ground effect, and tunnel walls on small scale models. This user's guide includes several case examples demonstrating user options. A complete listing of the FORTRAN program is provided.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165816 , NAS 1.26:165816 , AARL-TR-81-0
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  • 26
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    Two-photon excitation of nitric oxide fluorescence as a temperature indicator in unsteady gasdynamic processes (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A laser-induced fluorescence technique based on the pulsed two-photon excitation of NO is presented which is especially suited for the measurement of fluctuating temperatures in cold turbulent flows. The technique uses the fluorescence from the UV gamma bands of NO produced by two-photon excitation of NO (A 2 Sigma +, nu-prime = 0 - X 2 Pi, nu-double prime = 0) to obtain a rotational temperature. An analysis is presented of relevant aspects of the two-photon absorption process including microphysical processes, spectral intensities as a function of transition and laser spectral widths, line-shape integrals, the nonequilibrium response of the medium to a laser pulse, fluorescence energies, signal to noise ratio, and focusing effects. An analysis of absolute two-photon absorptivity measured in a nonflowing cell is then presented and used to predict signal to noise ratios greater than 50 for supersonic flows at temperatures below 300 K.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Applied Optics; 20; June 15
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  • 27
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    Effects of truncation in modal representations of thermal convection (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The Galerkin equations for convection in a sphere are examined to determine which physical processes are neglected by the severe truncation of the equations of motion. It is demonstrated that the gross features of the flow are affected by truncation in the horizontal direction, with all of the models considered being well resolved in the vertical direction. One of the effects of truncation is to enhance the high-wave number end of the kinetic energy and thermal variance spectra. The examples cited indicate that as long as the kinetic energy spectrum decreases with wave number, a truncation gives a qualitatively correct solution. Conclusions are tested by calculating solutions to the equations of motion for several values of the Rayleigh number and the limit of horizontal spatial resolution.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 103; Feb. 198
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  • 28
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    Heat transfer from a row of impinging jets to concave cylindrical surfaces (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Starting from the first principles, and with one experimentally obtained parameter, an expression for stagnation heat transfer is derived, applicable to round, impinging jets. The results obtained with a row of air jets impinging on an electrically-heated surface in a small-scale setup characteristic of a typical turbine blade have been found compatible with the average heat transfer from a geometrically similar, steam-heated surface scaled up ten times, and comparable with the results of other investigators. These findings were linked to the flow fields likely to exist in the gas turbine blades, internally cooled by a row of round jets or a single jet of equivalent width. The magnitude of heat-transfer coefficients obtained here with impinging jets approaches that normally associated with forced convection of water and evaporative cooling.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 24; Mar. 198
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  • 29
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    Interplanetary magnetic clouds at 1 AU (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Magnetic clouds are defined as regions with a radial dimension approximately 0.25 AU (at 1 AU) in which the magnetic field strength is high and the magnetic field direction changes appreciably by means of rotation of one component of B nearly parallel to a plane. The magnetic field geometry in such a magnetic cloud is consistent with that of a magnetic loop, but it cannot be determined uniquely. Forty-five clouds were identified in interplanetary data obtained near Earth between 1967 and 1978; at least one cloud passed the Earth every three months. Three classes of clouds were identified, corresponding to the association of a cloud with a shock, a stream interface, or a CME. There are approximately equal numbers of clouds in each class, and the three types of clouds might be different manifestations of a coronal transient. The magnetic pressure inside the clouds is higher than the ion pressure and the sum is higher than the pressure of the material outside of the cloud.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-82114
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  • 30
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    Unsteady Newton-Busemann flow theory. Part 2: Bodies of revolution (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Newtonian flow theory for unsteady flow past oscillating bodies of revolution at very high Mach numbers is completed by adding a centrifugal force correction to the impact pressures. Exact formulas for the unsteady pressure and the stability derivatives are obtained in closed form and are applicable to bodies of revolution that have arbitrary shapes, arbitrary thicknesses, and either sharp or blunt noses. The centrifugal force correction arising from the curved trajectories followed by the fluid particles in unsteady flow cannot be neglected even for the case of a circular cone. With this correction, the present theory is in excellent agreement with experimental results for sharp cones and for cones with small nose bluntness; gives poor agreement with the results of experiments in air for bodies with moderate or large nose bluntness. The pitching motions of slender power-law bodies of revulution are shown to be always dynamically stable according to Newton-Busemann theory.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-80459 , LOG-J12130-PT-2
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  • 31
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    Experimental data and model for the turbulent boundary layer on a convex, curved surface (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Experiments were performed to determine how boundary layer turbulence is affected by strong convex curvature. The data gathered on the behavior of the Reynolds stress suggested the formulation of a simple turbulence model. Data were taken on two separate facilities. Both rigs had flow from a flat surface, over a convex surface with 90 deg of turning and then onto a flat recovery surface. The geometry was adjusted so that, for both rigs, the pressure gradient along the test surface was zero. Two experiments were performed at delta/R approximately 0.10, and one at weaker curvature with delta/R approximately 0.05. Results show that after a sudden introduction of curvature the shear stress in the outer part of the boundary layer is sharply diminished and is even slightly negative near the edge. The wall shear also drops off quickly downstream. When the surface suddenly becomes flat again, the wall shear and shear stress profiles recover very slowly towards flat wall conditions. A simple turbulence model, which was based on the theory that the Prandtl mixing length in the outer layer should scale on the velocity gradient layer, was shown to account for the slow recovery.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3391 , HMT-31
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    Measurements of laminar and turbulent flow in a curved duct with thin inlet boundary layers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Laser Doppler velocimetry was used to measure the laminar and turbulent flow in a 90 deg square bend of strong curvature. The boundary layers at the inlet to the bend were approximately 25 percent and 15 percent of the hydraulic diameter for the laminar and turbulent flows, respectively. The development of the pressure driven secondary motion is more rapid for laminar flow: the maximum cross stream component measured was 60 percent of the bulk velocity in contrast to 40 percent for turbulent flow. The streamwise isotachs show that, for laminar flow, large velocities are found progressively nearer to the outer radius of the bend and along the sidewalls. For turbulent flow, the isotachs move towards the inner radius until about 60 deg around the bend where strong secondary motion results in a similar redistribution. Turbulence level and shear stress measurements are also presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3367 , FS-80-29
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    An extended classical solution of the droplet growth problem (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Problems of applying the classical kinetic theory to the growth of small droplets from vapor are examined. A solution for the droplet growth equation is derived which is based on the assumption of a diffusive field extending to the drop surface. The method accounts for partial thermal and mass accommodation at the interface and the kinetic limit to the mass and heat fluxes, and it avoids introducing the artifact of a discontinuity in the thermal and vapor field near the droplet. Consideration of the environmental fields in spherical geometry utilizing directional fluxes yields boundary values in terms of known parameters and a new Laplace transform integral.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-82392
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    Numerical simulation of natural convection in a spherical container due to cooling at the center (idealization of the Lal/Kroes experiment) (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Natural convection in a spherical container with cooling at the center was numerically simulated using a numerical fluid dynamics computer program. The numerical analysis was simplified by assuming axisymmetric flow in the spherical container, with the symmetry axis being a sphere diagonal parallel to the gravity vector. This axisymmetric spherical geometry was intended as an idealization of the proposed Lal/Kroes crystal growing experiment to be performed on Spacelab. Results were obtained for a range of Rayleigh numbers from 25 to 10,000. The computed velocities were found to be approximately proportional to the Rayleigh number over the range of Rayleigh numbers investigated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-163955 , LMSC-HREC-TR-D784100
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    Advanced stability analysis for laminar flow control (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Five classes of problems are addressed: (1) the extension of the SALLY stability analysis code to the full eighth order compressible stability equations for three dimensional boundary layer; (2) a comparison of methods for prediction of transition using SALLY for incompressible flows; (3) a study of instability and transition in rotating disk flows in which the effects of Coriolis forces and streamline curvature are included; (4) a new linear three dimensional instability mechanism that predicts Reynolds numbers for transition to turbulence in planar shear flows in good agreement with experiment; and (5) a study of the stability of finite amplitude disturbances in axisymmetric pipe flow showing the stability of this flow to all nonlinear axisymmetric disturbances.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165661 , CHI-43
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    Goertler instability (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Goertler instability for boundary-layer flows over generally curved walls is considered. The full-linearized disturbance equations are obtained in an orthogonal curvilinear coordinate system. A perturbation procedure to account for second-order effects is used to determine the effects of the displacement thickness and the variation of the streamline curvature on the neutral stability of the Blasius flow. The streamwise pressure gradient in the mean flow is accounted for by solving the nonsimilar boundary-layer equations. Growth rates are obtained for the actual mean flow and compared with those for the Blasius flow and the Falkner-Skan flows. The results demonstrate the strong influence of the streamwise pressure gradient and the nonsimilarity of the basic flow on the stability characteristics.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 24; Aug. 198
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    A study of the viscous and nonadiabatic flow in radial turbines (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A method for analyzing the viscous nonadiabatic flow within turbomachine rotors is presented. The field analysis is based upon the numerical integration of the incompressible Navier-Stokes equations together with the energy equation over the rotors blade-to-blade stream channels. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system that suits the most complicated blade geometries. Effects of turbulence are modeled with two equations; one expressing the development of the turbulence kinetic energy and the other its dissipation rate. The method of analysis is applied to a radial inflow turbine. The solution obtained indicates the severity of the complex interaction mechanism that occurs between different flow regimes (i.e., boundary layers, recirculating eddies, separation zones, etc.). Comparison with nonviscous flow solutions tend to justify strongly the inadequacy of using the latter with standard boundary layer techniques to obtain viscous flow details within turbomachine rotors. Capabilities and limitations of the present method of analysis are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Influence of velocity gradients on measurements of velocity and streamwise vorticity with hot-wire X-array probes (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An analysis and measurement of the effects of the streamwise velocity gradients partial derivative of U with respect to y and partial derivative of U with respect to z, on the velocity components, U, v, and w, and the streamwise vorticity component, omega sub x measured in turbulent flow with a pair of orthogonal hot-wire X arrays, is presented. It is shown that these gradients, which can have the same order of magnitude instantaneously as the mean shear stress at the wall, cause extremely large errors in the measured instantaneous cross-stream velocity and streamwise vorticity components.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Review of Scientific Instruments; 52; June 198
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    Finite-analytic numerical solution of heat transfer in two-dimensional cavity flow (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Heat transfer in cavity flow is numerically analyzed by a new numerical method called the finite-analytic method. The basic idea of the finite-analytic method is the incorporation of local analytic solutions in the numerical solutions of linear or nonlinear partial differential equations. In the present investigation, the local analytic solutions for temperature, stream function, and vorticity distributions are derived. When the local analytic solution is evaluated at a given nodal point, it gives an algebraic relationship between a nodal value in a subregion and its neighboring nodal points. A system of algebraic equations is solved to provide the numerical solution of the problem. The finite-analytic method is used to solve heat transfer in the cavity flow at high Reynolds number (1000) for Prandtl numbers of 0.1, 1, and 10.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Numerical Heat Transfer; 4; Apr
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    A simplified model for the viscous crossflow in a slotted test section (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A simplified physical model is 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, are obtained. Fairly general slot geometry is incorporated by means of the Thompson-Thames-Mastin transformation. An approximate factorization scheme with cyclic acceleration parameters is employed to solve a finite difference analog of the stream function equation. The vorticity equation is numerically solved with a modified version of the classical alternating direction implicit (ADI) scheme. Although no quantitative assessment of solution accuracy can be made, numerical results for variations in incremental wall pressure around the slot are at least qualitatively similar to some experimental results of Berndt and Sorenson.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computers and Fluids; 9; Mar. 198
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    Accuracy and convergence of a finite element algorithm for laminar boundary layer flow (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Galerkin-weighted residuals formulation is employed to derive an implicit finite element solution algorithm for a generally non-linear initial-boundary value problem. Solution accuracy and convergence with discretization refinement are quantized in several error norms, for the non-linear parabolic partial differential equation system governing laminar boundary layer flow, using linear, quadratic and cubic functions. Richardson extrapolation is used to isolate integration truncation error in all norms, and Newton iteration is employed for all equation solutions performed in double-precision. The mathematical theory supporting accuracy and convergence concepts for linear elliptic equations appears extensible to the non-linear equations characteristic of laminar boundary layer flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computers and Fluids; 9; Mar. 198
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    Methods for estimating pressure and thermal loads induced by elevon deflections on hypersonic-vehicle surfaces with turbulent boundary layers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Empirical anaytic methods are presented for calculating thermal and pressure distributions in three-dimensional, shock-wave turbulent-boundary-layer, interaction-flow regions on the surface of controllable hypersonic aircraft and missiles. The methods, based on several experimental investigations, are useful and reliable for estimating both the extent and magnitude of the increased thermal and pressure loads on the vehicle surfaces.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-83130 , L-14204
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    Simulation of ideal-gas flow by nitrogen and other selected gases at cryogenic temperatures (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The real gas behavior of nitrogen, the gas normally used in transonic cryogenic tunnels, is reported for the following flow processes: isentropic expansion, normal shocks, boundary layers, and interactions between shock waves and boundary layers. The only difference in predicted pressure ratio between nitrogen and an ideal gas which may limit the minimum operating temperature of transonic cryogenic wind tunnels occur at total pressures approaching 9 atm and total temperatures 10 K below the corresponding saturation temperature. These pressure differences approach 1 percent for both isentropic expansions and normal shocks. Alternative cryogenic test gases were also analyzed. Differences between air and an ideal diatomic gas are similar in magnitude to those for nitrogen and should present no difficulty. However, differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. It is concluded that helium and cryogenic hydrogen would not approximate the compressible flow of an ideal diatomic gas.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1901 , L-14587
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    Gortler vortices and transition in wall boundary layers of two Mach 5 nozzles (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The onset of transition in the wall boundary layers of two axisymmetric Mach 5 wind-tunnel nozzles has been measured under conditions of extremely low incident disturbance levels. The range of test unit Reynolds numbers, based on conditions at the nozzle exit, was from 6 x 10 to the 6th power m to 2.5 x 10 to the 7th power m. When the nozzle walls were maintained in a polished and clean condition, transition moved gradually upstream as the test Reynolds number was increased. When transition occurred in the supersonic concave wall region, the values of the local Gortler parameter at transition varied from about 5 to 6, whereas the momentum thickness Reynolds number varied from about 750 to 1050. Oil flow patterns obtained near the exit of the nozzles indicated that Gortler vortices were always present when the wall boundary layers were laminar. Calculations for the growth of Gortler vortices based on new results from linear theory for supersonic flat-plate profiles gave amplification ratios to transition from e to the 4th power to e to the 15th power. Possible reasons for this wide range in amplification ratios are discussed, but no definite conclusions are yet possible regarding the values of n in a simple e to the nth power type theory for the assumed linear amplification of Gortler vortices to transition in supersonic nozzles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1869 , L-14332
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    Numerical experiments in homogeneous turbulence (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The direct simulation methods developed by Orszag and Patternson (1972) for isotropic turbulence were extended to homogeneous turbulence in an incompressible fluid subjected to uniform deformation or rotation. The results of simulations for irrotational strain (plane and axisymmetric), shear, rotation, and relaxation toward isotropy following axisymmetric strain are compared with linear theory and experimental data. Emphasis is placed on the shear flow because of its importance and because of the availability of accurate and detailed experimental data. The computed results are used to assess the accuracy of two popular models used in the closure of the Reynolds-stress equations. Data from a variety of the computed fields and the details of the numerical methods used in the simulation are also presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81315
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    Modification in drag of turbulent boundary layers resulting from manipulation of large-scale structures (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effects of placing a parallel-plate turbulence manipulator in a boundary layer are documented through flow visualization and hot wire measurements. The boundary layer manipulator was designed to manage the large scale structures of turbulence leading to a reduction in surface drag. The differences in the turbulent structure of the boundary layer are summarized to demonstrate differences in various flow properties. The manipulator inhibited the intermittent large scale structure of the turbulent boundary layer for at least 70 boundary layer thicknesses downstream. With the removal of the large scale, the streamwise turbulence intensity levels near the wall were reduced. The downstream distribution of the skin friction was also altered by the introduction of the manipulator.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3444
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    SEP BIMOD variable conductance heat pipes acceptance and characterization tests (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of six heat pipes, similar in design to those flown on the Comunications Technology Satellite Hermes, for use in a prototype Solar Electric Propulsion BIMOD thrust module are evaluated. The results of acceptance and characterization tests performed on the heat pipe subassemble are reported. The performance of all the heat pipes met, or exceeded, design specifications.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-82635 , E-857
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    Numerical investigation of turbulent channel flow (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Fully developed turbulent channel flow was simulated numerically at Reynolds number 13800, based on centerline velocity and channel halt width. The large-scale flow field was obtained by directly integrating the filtered, three dimensional, time dependent, Navier-Stokes equations. The small-scale field motions were simulated through an eddy viscosity model. The calculations were carried out on the ILLIAC IV computer with up to 516,096 grid points. The computed flow field was used to study the statistical properties of the flow as well as its time dependent features. The agreement of the computed mean velocity profile, turbulence statistics, and detailed flow structures with experimental data is good. The resolvable portion of the statistical correlations appearing in the Reynolds stress equations are calculated. Particular attention is given to the examination of the flow structure in the vicinity of the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81309 , A-8659
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    Weighted-mean scheme for solving incompressible viscous flow (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The problem of how a boundary layer responds to the motion of a convexed vortex on a porous wall was investigated. The wall velocity is approximately given by Darcy's law. The vorticity-stream function approach was adopted for solving Navier-Stokes equations of two dimensional incompressible viscous flows. The weighted-mean scheme was used for constructing finite difference approximations of spatial derivatives. Several test problems were solved and numerical results demonstrate clearly the accuracy, stability, and efficiency of the scheme. The weighted mean scheme then can be applied to the vortical flow problem.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165747 , R-SAL-05/81-01
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    Influence of thermal boundary conditions on heat transfer from a cylinder in cross flow (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Local heat transfer data over the leading surface of a cylinder in crossflow were obtained for a Reynolds number range of 50,000. The cylinder was operated at both uniform-wall-temperature and uniform-heat-flux thermal ance of 80 deg from the front stagnation point, the uniform-wall-temperature heat transfer coefficients were as much as 66 percent lower than the uniform-heat-flux data. Between the stagnation point and 60 deg around the cylinder, there were no significant differences in the data. This region of the cylinder is within the cylindrical curvature region of the front end of a real turbine so it was concluded that either thermal boundary condition could be used to model turbine flow over that region of the blade. Results of evaluating the exponent x in the fundamental relationship Nu=f(Re) sup x, which is used in data correlation show the exponent varies as a function of local position on the cylinder even in the laminar flow region. The value of x increases linearly from 0.50 at the stagnation point to 0.59 at 60 deg around the cylinder. This linear trend continued into the separation region at 80 deg for the uniform-wall-temperature data, but x increased markedly in the separation region for the uniform-heat-flux data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1894 , E-627
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    Approximate factorization for incompressible flow (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: For computational solution of the incompressible Navier-Stokes equations, the approximate factorization (AF) algorithm is used to solve the vectorized momentum equation in delta form based on the pressure calculated in the previous time step. The newly calculated velocities are substituted into the pressure equation (obtained from a linear combination of the continuity and momentum equation), which is then solved by means of line SOR. Computational results are presented for the NACA 66 sub 3 018 airfoil at Reynolds numbers of 1000 and 40,000 and attack angles of 0 and 6 degrees. Comparison with wind tunnel data for Re = 40,000 indicates good qualitative agreement between measured and calculated pressure distributions. Quantitative agreement is only fair, however, with the calculations somewhat displaced from the measurements. Furthermore, the computed velocity profiles are unrealistically thick around the airfoil, due to the excessive amount of artificial viscosity needed for stability. Based on the performance of the algorithm with regard to stability, it is concluded that AF/SOR is suitable for calculations at Reynolds numbers less than 10,000. Speedwise, the method is faster than point SOR by at least a factor of two.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-164668 , AASE-81-232
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    Automatic flowmeter calibration system (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A system for automatically calibrating the accuracy of a flowmeter is described. The system includes a calculator capable of performing mathematical functions responsive to receiving data signals and function command signals. A prover cylinder is provided for measuring the temperature, pressure, and time required for accumulating a predetermined volume of fluid. Along with these signals, signals representing the temperature and pressure of the fluid going into the meter are fed to a plurality of data registers. Under control of a progress controller, the data registers are read out and the information is fed through a data select circuit to the calculator. Command signals are also produced by a function select circuit and are fed to the calculator set indicating the desired function to be performed. The reading is then compared with the reading produced by the flowmeter.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Effects of a modified leading edge on noise and boundary-layer transition in a rod-wall sound shield at Mach 5 (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A version of a rod wall sound shield was tested in the Mach 5 pilot quiet tunnel over a range of unit Reynolds numbers from 10 to 35 million per meter. The model was modified by inclining the leading edge plates to produce an initial 2 deg expansion to ascertain the sensitivity of boundary layer transition to leading edge disturbances. Rod surface pitot pressures, mean free stream pitot pressures, and static pressures on the rods and plenum walls were measured. Hot-wire measurements were also made in the model and nozzle free stream at a unit Reynolds number of 15 million per meter. The surface pitot pressures indicated that transition was much farther forward than for the previous tests due to the leading edge modification and minor fabrication flaws in the model. Early boundary layer transition on the rods was confirmed by hot-wire measurements which showed much higher noise levels in the free stream shield flow when compared with results from previous tests. Mean pitot pressure surveys within the shielded region inside the model indicated that there was an overexpansion and recompression that would limit the streamwise length of undisturbed flow to about 13 cm along the centerline.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81935 , L-14196
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    Computation of unsteady turbulent boundary layers with flow reversal and evaluation of two separate turbulence models (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A procedure which solves the governing boundary layer equations within Keller's box method was developed for calculating unsteady laminar flows with flow reversal. This method is extended to turbulent boundary layers with flow reversal. Test cases are used to investigate the proposition that unsteady turbulent boundary layers also remain free of singularities. Turbulent flow calculations are performed. The governing equations for both models are solved. As in laminar flows, the unsteady turbulent boundary layers are free from singularities, but there is a clear indication of rapid thickening of the boundary layer with increasing flow reversal. Predictions of both turbulence models are the same for all practical purposes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81259 , A-8438
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    Calculation of sensitivity derivatives in thermal problems by finite differences (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The optimum design of a structure subject to temperature constraints is considered. When mathematical optimization techniques are used, derivatives of the temperature constraints with respect to the design variables are usually required. In the case of large aerospace structures, such as the Space Shuttle, the computation of these derivatives can become prohibitively expensive. Analytical methods and a finite difference approach have been considered in studies conducted to improve the efficiency of the calculation of the derivatives. The present investigation explores two possibilities for enhancing the effectiveness of the finite difference approach. One procedure involves the simultaneous solution of temperatures and derivatives. The second procedure makes use of the optimum selection of the magnitude of the perturbations of the design variables to achieve maximum accuracy.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering; 17; Dec. 198
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    A mathematical model of a large open fire (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A mathematical model capable of predicting the detailed characteristics of large, liquid fuel, axisymmetric, pool fires is described. The predicted characteristics include spatial distributions of flame gas velocity, soot concentration and chemical specie concentrations including carbon monoxide, carbon dioxide, water, unreacted oxygen, unreacted fuel and nitrogen. Comparisons of the predictions with experimental values are also given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-166475 , NAS 1.26:166475
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  • 57
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    Accuracy and convergence of a finite element algorithm for turbulent boundary layer flow (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The Galerkin-Weighted Residuals formulation is employed to derive an implicit finite element solution algorithm for the nonlinear parabolic partial differential equation system governing turbulent boundary layer flow. Solution accuracy and convergence with discretization refinement are quantized in several error norms using linear and quadratic basis functions. Richardson extrapolation is used to isolate integration truncation error in all norms, and Newton iteration is employed for all equation solutions performed in double-precision. The mathematical theory supporting accuracy and convergence concepts for linear elliptic equations appears extensible to the nonlinear equations characteristic of turbulent boundary layer flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computer Methods in Applied Mechanics and Engineering; 28; Aug. 198
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    Eigenvalues of the Rayleigh-Benard and Marangoni problems (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The eigenvalues of the linear Benard-Marangoni stability problem are discussed. Pearson and Nield boundary conditions, which correspond to a rigid, isothermal lower boundary and a stress-free conducting upper boundary are considered. It is shown that although a critical value of the Marangoni number can be determined, the number is not, strictly speaking, an eigenvalue and cannot be used as an eigenvalue parameter for the determination of an eigenvector set.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 24; Nov. 198
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    Chaotic behavior and fluid dynamics (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: It is shown that while fluids are very complicated systems having many degrees of freedom, the basic mechanism underlying the observed chaotic behavior of fluid turbulence may not require the consideration of many degrees of freedom. Simple dynamical systems display erratic and chaotic behavior reminiscent of turbulence, the key to which is the 'sensitivity to initial conditions' introduced by Ruelle (1978). Simple models which are sensitive to initial data and have permitted workers to study chaotic behavior are described, with attention to the Lorenz equations, Landau's idea of a continuous transition to turbulence via an infinite cascade of bifurcations, and one-dimensional maps.
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    The 'preferred mode' of the axisymmetric jet (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Detailed distributions of different time-average and phase-average flow properties for an axisymmetric free jet under controlled perturbation at the jet preferred mode are explored. The data are compared with the corresponding unexcited jet data. It is found that the effect of the perturbation is to increase jet spread and mean velocity decay, as well as to increase the peak values of the time-average fluctuation intensities and Reynolds stress in the axisymmetric mixing layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 110; Sept
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  • 61
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    On the growth of turbulent regions in laminar boundary layers (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Turbulent spots evolving in a laminar boundary layer on a nominally zero pressure gradient flat plate are investigated. The plate is towed through an 18 m water channel, using a carriage that rides on a continuously replenished oil film giving a vibrationless tow. Turbulent spots are initiated using a solenoid valve that ejects a small amount of fluid through a minute hole on the working surface. A novel visualization technique that utilizes fluorescent dye excited by a sheet of laser light is employed. Some new aspects of the growth and entrainment of turbulent spots, especially with regard to lateral growth, are inferred from the present experiments. To supplement the information on lateral spreading, a turbulent wedge created by placing a roughness element in the laminar boundary layer is also studied both visually and with probe measurements. The present results show that, in addition to entrainment, another mechanism is needed to explain the lateral growth characteristics of a turbulent region in a laminar boundary layer. This mechanism, termed growth by destabilization, appears to be a result of the turbulence destabilizing the unstable laminar boundary layer in its vicinity. To further understand the growth mechanisms, the turbulence in the spot is modulated using drag-reducing additives and salinity stratification.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AD-A112127 , ARO-16651.1-E , Journal of Fluid Mechanics; 110; Sept
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    The heat pipe thermal canister (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The thermal canister represents a new approach to instrument thermal control for Shuttle experiments which require tight temperature control. The canister substitutes a known, benign thermal environment for the variable and uncertain environment of space, the space environment being neutralized by a system of feedback controlled variable conductance heat pipes. A proto-flight unit has been fabricated and this paper describes the acceptance thermal vacuum test results of the thermal canister experiment which will fly on an early Space Shuttle flight.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 80-1461
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    Effect of streamwise vortices on Tollmien-Schlichting waves (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    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 oblique Tollmien-Schlichting waves. The results show that such vortices have a strong tendency to amplify oblique 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 exponential growth rates increase linearly with increasing amplitudes of the vortices. Numerical results are presented. They suggest that this mechanism may dominate the instability.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 107; June 198
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  • 64
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    The continuous spectrum of the Orr-Sommerfeld equation. II - Eigenfunction expansions (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 104; Mar. 198
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  • 65
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    Transition in the axisymmetric jet (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Unsteady particle trajectories are used to study structural features associated with the Reynolds-number dependence of an axisymmetric jet. It is found that transition in the unbounded jet is in the nature of transition in Couette flow and occurs at specific critical values of the Reynolds number rather than in some range over which small disturbances are amplified. In the case of the creeping-flow solution, the particle-path pattern exhibits a structure which is not easily discerned in any of the other variables that govern the flow. For sufficiently small Reynolds number, the particle paths converge to a single stable node which lies on the axis of the jet. At a Reynolds number of 6.7806, the pattern bifurcates to a saddle and two stable nodes; at a Reynolds number of 10.09089, it bifurcates a second time to form a saddle and two stable foci.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 104; Mar. 198
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  • 66
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    Asymptotic form of the longitudinal correlation function for isotropic homogeneous turbulence (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An asymptotic form is derived for the longitudinal correlation function for isotropic homogeneous turbulence in an incompressible fluid governed by the Navier-Stokes equation. The result is obtained from an analysis of the algebraic-differential structure of the two-point correlation tensor contained in the complex-valued Fourier transform of the probability measure over the turbulence ensemble, which reveals that the Hopf characteristic functional (the complex-valued Fourier transform of the probability measure) satisfies the Fourier interference inequality. Consequences of the expression obtained, in which the correlation function is a positive definite function of the inverse cube of the spatial coordinate as it approaches infinity, are shown to include the nonexistence of the Loitsianskii invariant, and the solution is shown to be consistent with empirical formulas.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 24; Mar. 198
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  • 67
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    Simulation of three-dimensional incompressible flows with a vortex-in-cell method (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A new method for the numerical simulation of three-dimensional incompressible flows is described. The vortex-in-cell (VIC) method presented traces the motion of the vortex filaments in the velocity field which these filaments create. The velocity field is not calculated directly by the Biot-Savart law of interaction but by creating a mesh-record of the vorticity field, then integrating a Poisson's equation via the fast Fourier transform to generate a mesh-record of the velocity field. The computed scales of motion are assumed to be essentially inviscid. Viscous of subgrid-scale effects are incorporated into a filtering procedure in wave vector space. Results of tracing a periodic array of single vortex rings are compared with a Green's function calculation. The agreement is very good.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AD-A099486 , Journal of Computational Physics; 39; Feb. 198
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    Turbulence suppression in free shear flows by controlled excitation (1981)
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    Publication Date: 2019-06-28
    Description: Turbulence suppression in the near field of a free shear flow under controlled excitation is investigated in four circular jets, a plane jet, and a plane mixing layer. The suppression is a consequence of an excitation-induced modification of the shear layer structure and occurs at the excitation frequency corresponding to the maximally unstable disturbance frequency of the initial free shear layer. The most pronounced suppression occurs when the shear layer is excited at a frequency 40% higher than the natural roll-up frequency. Excitation at a Strouhal number of about 0.017 produces a rapid roll-up and early breakdown of the shear layer, and thus inhibits the formation of the energetic large-scale vortices which otherwise survive farther downstream, grow to larger sizes, and undergo successive pairings in the corresponding unexcited flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 103; Feb. 198
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  • 69
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    A study of the interactions between large-scale coherent structures and fine-grained turbulence in a round jet (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An approximate energy integral description is used to study the development of large-scale coherent structures in the technologically important problem of the round turbulent jet. The analysis begins from the radially integrated form of the kinetic energy equations of the mean flow, the large-scale structure and the fine-grained turbulence, which are obtained by using the usual Reynolds time average and a conditional average with reference to the frequency of the idealized monochromatic component of the large-scale wavelike structure. This is the basis for obtaining the amplitude equations for the three components of the flow in terms of the mean flow momentum thickness, the large-scale structure kinetic energy and the fine-grained turbulence kinetic energy across the jet.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AD-A106993
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  • 70
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    Liquid spray cooling of a heated surface (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The lowest surface temperature possible for the existance of spray evaporative cooling is determined experimentally to be a linear function of the impinging spray mass flux. A conduction-controlled analytical model of droplet evaporation gives fairly good agreement with experimental measurements at atmospheric pressure. At reduced pressures droplet evaporation rates are decreased significantly such that an optimum operating pressure exists for each desired surface heat flux. The initiation of the 'Leidenfrost state' provides the upper surface temperature bound for spray evaporative cooling.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 24; Feb. 198
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  • 71
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    Conservation form of the Navier-Stokes equations in general nonsteady coordinates (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 19; Feb. 198
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  • 72
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    Algorithm for rapid integration of turbulence model equations on parabolic regions (1981)
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    Publication Date: 2019-06-28
    Description: While developing a three-dimensional boundary layer program using a standard parabolic matching scheme, the author has found computing time with the Wilcox-Rubesin (1979) two-equation turbulence model to be very lengthy. The long computing time occurs because converged solutions are possible only when very small streamwise steps are taken. The proposed remedy reduces computing time by increasing the maximum permissible step size.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 19; Feb. 198
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    Elasto visco-plastic flow with special attention to boundary conditions (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A simple but nontrivial steady-state creeping elasto visco-plastic (Maxwell fluid) radial flow problem is analyzed, with special attention given to the effects of the boundary conditions. Solutions are obtained through integration of a governing equation on stress using the Runge-Kutta method for initial value problems and finite differences for boundary value problems. A more general approach through the finite element method, an approach that solves for the velocity field rather than the stress field and that is applicable to a wide range of problems, is presented and tested using the radial flow example. It is found that steady-state flows of elasto visco-plastic materials are strongly influenced by the state of stress of material as it enters the region of interest. The importance of this boundary or initial condition in analyses involving materials coming into control volumes from unusual stress environments is emphasized.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Engineering; 17; Jan. 198
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  • 74
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    On the effect of boundary layer growth on the stability of compressible flows (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The method of multiple scales is used to describe a formally correct method based on the nonparallel linear stability theory, that examines the two and three dimensional stability of compressible boundary layer flows. The method is applied to the supersonic flat plate layer at Mach number 4.5. The theoretical growth rates are in good agreement with experimental results. The method is also applied to the infinite-span swept wing transonic boundary layer with suction to evaluate the effect of the nonparallel flow on the development of crossflow disturbances.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3474
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    Prediction of boundary-layer characteristics of an oscillating airfoil (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The evolution of unsteady boundary layers on oscillating airfoils is investigated by solving the governing equations by the Characteristic Box scheme. The difficulties associated with computing the first profile on a given time line, and the velocity profiles with partial flow reversal are solved. A sample calculation is performed for an external velocity distribution typical of those found near the leading edge of thin airfoils. The viability of the calculation procedure is demonstrated.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81303 , A-8639 , USAAVRADCOM-TR-81-B-18
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    Depressurization and two-phase flow of water containing high levels of dissolved nitrogen gas (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Depressurization of water containing various concentrations of dissolved nitrogen gas was studied. In a nonflow depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and a metastable behavior which was a strong function of the depressurization rate was observed. Flow experiments were performed in an axisymmetric, converging diverging nozzle, a two dimensional, converging nozzle with glass sidewalls, and a sharp edge orifice. The converging diverging nozzle exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of the saturation level. The flow rates were independent of concentration level. Flow in the two dimensional, converging, visual nozzle appeared to have a sufficient pressure drop at the throat to cause nitrogen to come out of solution, but choking occurred further downstream. The orifice flow motion pictures showed considerable oscillation downstream of the orifice and parallel to the flow. Nitrogen bubbles appeared in the flow at back pressures as high as 3.28 MPa, and the level at which bubbles were no longer visible was a function of nitrogen concentration.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1839 , E-216
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    Stagnation region gas film cooling: Spanwise angled injection from multiple rows of holes (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The stagnation region of a cylinder in a cross flow was used in experiments conducted with both a single row and multiple rows of spanwise angled (25 deg) coolant holes for a range of the coolant blowing ratio with a freestream to wall temperature ratio approximately equal to 1.7 and R(eD) = 90,000. Data from local heat flux measurements are presented for injection from a single row located at 5 deg, 22.9 deg, 40.8 deg, 58.7 deg from stagnation using a hole spacing ratio of S/d(o) = 5 and 10. Three multiple row configurations were also investigated. Data are presented for a uniform blowing distribution and for a nonuniform blowing distribution simulating a plenum supply. The data for local Stanton Number reduction demonstrated a lack of lateral spreading by the coolant jets. Heat flux levels larger than those without film cooling were observed directly behind the coolant holes as the blowing ratio exceeded a particular value. The data were spanwise averaged to illustrate the influence of injection location, blowing ratio and hole spacing. The large values of blowing ratio for the blowing distribution simulating a plenum supply resulted in heat flux levels behind the holes in excess of the values without film cooling. An increase in freestream turbulence intensity from 4.4 to 9.5 percent had a negligible effect on the film cooling performance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165333
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    Reduction of the two dimensional stationary Navier-Stokes problem to a sequence of Fredholm integral equations of the second kind (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Present approaches to solving the stationary Navier-Stokes equations are of limited value; however, there does exist an equivalent representation of the problem that has significant potential in solving such problems. This is due to the fact that the equivalent representation consists of a sequence of Fredholm integral equations of the second kind, and the solving of this type of problem is very well developed. For the problem in this form, there is an excellent chance to also determine explicit error estimates, since bounded, rather than unbounded, linear operators are dealt with.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81272 , A-8494 , USAAVRADCOM-TR-81-A-10
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    Forced and natural convection in laminar-jet diffusion flames (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted on methane, laminar-jet, diffusion flames with coaxial, forced-air flow to examine flame shapes in zero-gravity and in situations where buoyancy aids (normal-gravity flames) or hinders (inverted-gravity flames) the flow velocities. Fuel nozzles ranged in size from 0.051 to 0.305 cm inside radius, while the coaxial, convergent, air nozzle had a 1.4 cm inside radius at the fuel exit plane. Fuel flows ranged from 1.55 to 10.3 cu cm/sec and air flows from 0 to 597 cu cm/sec. A computer program developed under a previous government contract was used to calculate the characteristic dimensions of normal and zero-gravity flames only. The results include a comparison between the experimental data and the computed axial flame lengths for normal gravity and zero gravity which showed good agreement. Inverted-gravity flame width was correlated with the ratio of fuel nozzle radius to average fuel velocity. Flame extinguishment upon entry into weightlessness was studied, and it was found that relatively low forced-air velocities (approximately 10 cm/sec) are sufficient to sustain methane flame combustion in zero gravity. Flame color is also discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1841 , E-487
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    Some flow phenomena associated with aligned, sequential apertures with Borda-type inlets (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Choked flow rate and pressure profile data were taken and studied for a configuration consisting of four axially aligned, sequential Borda tubes of 1.9 length diameter ratio with separation distances of 0.8 and 30 tube diameters. For either case the flow rate data could be represented by a flow coefficient reduced temperature plot. At a separation distance of 30 tube diameters the pressure profiles dropped sharply at the entrance and recovered within each Borda tube; except at low temperatures, where fluid jetting through the last Borda tube occurred. At a separation distance of 0.8 tube jetting was prevalent, and application of a significant backpressure did not alter the jetting. These results agree with other data for tubes with Borda or sharp edge orifice inlets and with a water flow visualization study reported herein.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1792 , E-479
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    Studies of compressible shear flows and turbulent drag reduction (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Compressible shear flows and drag reduction were examined and three methods are addressed: (1) the analytical and numerical aspects of conformal mapping were summarized and a new method for computation of these maps is presented; (2) the computer code SPECFD for solution of the three dimensional time dependent Navier-Stokes equations for compressible flow on the CYBER 203 computer is described; (3) results of two equation turbulence modeling of turbulent flow over wavy walls are presented. A modified Jones-Launder model is used in two dimensional spectral code for flow in general wavy geometries.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165690 , CHI-49
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    Multiple-scale turbulence modeling of boundary layer flows for scramjet applications (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: As part of an investigation into the application of turbulence models to the computation of flows in advanced scramjet combustors, the multiple-scale turbulence model was applied to a variety of flowfield predictions. The model appears to have a potential for improved predictions in a variety of areas relevant to combustor problems. This potential exists because of the partition of the turbulence energy spectrum that is the major feature of the model and which allows the turbulence energy dissipation rate to be out of phase with turbulent energy production. The computations were made using a consistent method of generating experimentally unavailable initial conditions. An appreciable overall improvement in the generality of the predictions is observed, as compared to those of the basic two-equation turbulence model. A Mach number-related correction is found to be necessary to satisfactorily predict the spreading rate of the supersonic jet and mixing layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3433 , SAI-80-022-CP
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  • 83
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    Mean-flow and turbulence measurements in the vicinity of the trailing edge of an NACA (63 sub 1)-012 airfoil (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Langley aircraft noise reduction laboratory was used to measure mean flow and turbulence in the vicinity of a cusped-trailing edge of two dimensional NACA 631-012 airfoil at zero angle of attack. Naturally transitioned flow and artificially tripped flow were investigated. Flow regions studied include the boundary layer and the near wake. Measurements were made at a free stream Reynolds number based on airfoil chord of 1.25 x 10 to the 6th power and a free stream Mach number of 0.1. Distributions of streamwise mean velocity, integral properties of the mean flow, turbulent intensities, and Reynolds shear stress are reported. For the naturally transitioned flow, the general trends observed are similar to those reported for a fully developed turbulent boundary layer over a flat plate under zero pressure gradient, with the exception of the notable streamwise variations in the turbulence properties for the airfoil flow. The main effect of flow tripping is to eliminate these streamwise variations. Observed changes in the mean flow and turbulence fields caused by tripping are expected on the basis of the Reynolds number based on the boundary layer thickness.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1845 , L-13959
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    Instability and transition in rotating disk flow (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The stability of three dimensional rotating disk flow and the effects of Coriolis forces and streamline curvature were investigated. It was shown that this analysis gives better growth rates than Orr-Sommerfeld equation. Results support the numerical prediction that the number of stationary vortices varies directly with the Reynolds number.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165689 , R-SAL-3/81-01
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  • 85
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    Capillary and acceleration wave breakup of liquid jets in axial-flow airstreams (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Empirical correlations of reciprocal mean drop diameter with airstream momentum were derived from capillary and acceleration wave breakup of liquid jets atomized by cross stream injection into axial flow airstreams. A scanning radiometer was used to obtain data over an airstream momentum range of 3.7 to 25.7 g/sq cm sec. Transition from capillary to acceleration wave breakup was obtained at a critical Weber-Reynolds number of 1,000,000.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1791 , E-537
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    Superfluid helium leak sealant study (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Twenty-one leak specimens were fabricated in the ends of stainless steel and aluminum tubes. Eighteen of these tubes were coated with a copolymer material to seal the leak. The other three specimens were left uncoated and served as control specimens. All 21 tubes were cold shocked in liquid helium 50 times and then the leak rate was measured while the tubes were submerged in superfluid helium at 1.7 K. During the cold shocks two of the coated specimens were mechanically damaged and eliminated from the test program. Of the remaining 16 coated specimens one suffered a total coating failure and resulting high leak rate. Another three of the coated specimens suffered partial coating failures. The leak rates of the uncoated specimens were also measured and reported. The significance of various leak rates is discussed in view of the infrared astronomical satellite (IRAS) Dewar performance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81212 , A-8233
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    Jet array impingement with crossflow-correlation of streamwise resolved flow and heat transfer distributions (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Correlations for heat transfer coefficients for jets of circular offices and impinging on a surface parallel to the jet orifice plate are presented. The air, following impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer (impingement) surface. The downstream jets are subjected to a crossflow originating from the upstream jets. Impingement surface heat transfer coefficients resolved to one streamwise jet orifice spacing, averaged across the channel span, are correlated with the associated individual spanwise orifice row jet and crossflow velocities, and with the geometric parameters.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3373 , ERC-R-80024
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    Study of liquid slosh in the tracking and data relay satellite hydrazine tanks (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental study was conducted to provide data for evaluation of the parameters for an analytical mechanical model representation of liquid/interface dynamics in the TDRSS propellant tanks. Models were developed for two liquid-under ullage (forward tank) configurations and for one liquid-over-ullage (aft tank) configuration. However, additional test runs were conducted with liquids of different densities in both cases to allow separation of bladder stiffness and gravity effects under various simulated steady acceleration conditions. Both static and dynamic parameters are evaluated to provide a good prediction of observed results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-166745
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    The development of a high-capacity instrument module heat transport system, appendixes (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Data sheets provide temperature requirements for 82 individual instruments that are under development or planned for grouping on a space platform or pallet. The scientific objectives of these instrument packages are related to solar physics, space plasma physics, astronomy, high energy astrophysics, resources observations, environmental observations, materials processing, and life sciences. System specifications are given for a high capacity instrument module heat transport system to be used with future payloads.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-175260 , NAS 1.26:175260
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    Controlled overspray spray nozzle (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A spray system for a multi-ingredient ablative material wherein a nozzle A is utilized for suppressing overspray is described. The nozzle includes a cyclindrical inlet which converges to a restricted throat. A curved juncture between the cylindrical inlet and the convergent portion affords unrestricted and uninterrupted flow of the ablative material. A divergent bell-shaped chamber and adjustable nozzle exit B is utilized which provides a highly effective spray pattern in suppressing overspray to an acceptable level and producing a homogeneous jet of material that adheres well to the substrate.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    HADY-I, a FORTRAN program for the compressible stability analysis of three-dimensional boundary layers (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computer program HADY-I for calculating the linear incompressible or compressible stability characteristics of the laminar boundary layer on swept and tapered wings is described. The eigenvalue problem and its adjoint arising from the linearized disturbance equations with the appropriate boundary conditions are solved numerically using a combination of Newton-Raphson interative scheme and a variable step size integrator based on the Runge-Kutta-Fehlburh fifth-order formulas. The integrator is used in conjunction with a modified Gram-Schmidt orthonormalization procedure. The computer program HADY-I calculates the growth rates of crossflow or streamwise Tollmien-Schlichting instabilities. It also calculates the group velocities of these disturbances. It is restricted to parallel stability calculations, where the boundary layer (meanflow) is assumed to be parallel. The meanflow solution is an input to the program.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3467
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    Numerical simulation of a compressible homogeneous, turbulent shear flow (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A direct, low Reynolds number, numerical simulation was performed on a homogeneous turbulent shear flow. The full compressible Navier-Stokes equations were used in a simulation on the ILLIAC IV computer with a 64,000 mesh. The flow fields generated by the code are used as an experimental data base, to examine the behavior of the Reynols stresses in this simple, compressible flow. The variation of the structure of the stresses and their dynamic equations as the character of the flow changed is emphasized. The structure of the tress tensor is more heavily dependent on the shear number and less on the fluctuating Mach number. The pressure-strain correlation tensor in the dynamic uations is directly calculated in this simulation. These correlations are decomposed into several parts, as contrasted with the traditional incompressible decomposition into two parts. The performance of existing models for the conventional terms is examined, and a model is proposed for the 'mean fluctuating' part.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-164953 , SU-TF-13
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    Surface-tension induced instabilities: Effects of lateral boundaries (1981)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Convection in circular and rectangular cylinders is analyzed. The governing equations and boundary conditions are formulated, linear and nonlinear stability theory are considered, and the physical implications of the theory are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-165530
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    Amplified crossflow disturbances in the laminar boundary layer on swept wings with suction (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Solution charts of the Orr-Sommerfeld equation for stationary crossflow disturbances are presented for 10 typical velocity profiles on a swept laminar flow control wing. The critical crossflow Reynolds number is shown to be a function of a boundary layer shape factor. Amplification rates for crossflow disturbances are shown to be proportional to the maximum crossflow velocity. A computer stability program called MARIA, employing the amplification rate data for the 10 crossflow velocity profiles, is constructed. This code is shown to adequately approximate more involved computer stability codes using less than two percent as much computer time while retaining the essential physical disturbance growth model.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TP-1902 , L-14423
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    Grid-generated isotropic homogeneous turbulence at high Reynolds numbers (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Consideration is given to an empirical formula for the longitudinal correlation function for grid-generated incompressible fluid turbulence at Reynolds numbers above 12,800. The formula, which relates the longitudinal correlation function to the inverse cube of a dimensionless geometrical ratio, is shown to minimize the global correlation integrals into which the two-point velocity correlation tensor has been substituted subject to a global constraint on the Sobolev concomitent of the longitudinal correlation function. Furthermore, the energy spectrum function associated with the empirical formula is shown to satisfy a tertiary Helmholtz-type linear condition throughout the initial period of decay.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Optimal time splitting for two- and three-dimensional Navier-Stokes equations with mixed derivatives (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A new explicit, time splitting algorithm has been developed for finite difference modelling of the full two and three-dimensional time-dependent, compressible, viscous Navier-Stokes equations of fluid mechanics. The scheme is optimal in the sense that the split operators achieve their maximum allowable time step, i.e., the corresponding Courant number. The algorithm allows a conservation-form formulation. Stability is proven analytically and verified numerically. In proving stability it was shown that all nine matrix coefficients of the Navier-Stokes equations are simultaneously symmetrizable by a similarity transformation. Two such transformations and their resulting symmetric matrix coefficients are presented explicitly.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 41; May 1981
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    Organized motion in turbulent flow (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A review of organized motion in turbulent flow indicates that the transport properties of most shear flows are dominated by large-scale vortex nonrandom motions. The mean velocity profile of a turbulent boundary layer consists of a viscous sublayer, buffer layer, and a logarithmic outer layer; an empirical formula of Coles (1956) applies to various pressure gradients. The boundary layer coherent structure was isolated by the correlation methods of Townsend (1956) and flow visualization by direct observations of complex unsteady turbulent motions. The near-wall studies of Willmart and Wooldridge (1962) used the space-time correlation for pressure fluctuations at the wall under a thick turbulent boundary layer; finally, organized motion in free shear flows and transition-control of mixing demonstrated that the Reynolds number invariance of turbulence shows wide scatter.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Evacuation-induced pressure differentials in multilayer insulation systems (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The pressure differentials induced across three types of multilayer insulation systems during evacuation have been measured and compared with values predicted using an idealized parallel plate geometric model. The systems tested were double-aluminized Mylar with a Tissuglas or silk net spacer and crinkled single-aluminized Mylar. Test samples were circular. The influence of purge gas type, layer density, sample diameter, and temperature was systematically investigated. The experimental approach was to measure the absolute pressure history and corresponding pressure differential induced across the insulation during evacuation. The measured pressure differentials were nondimensionalized and compared with those predicted by the parallel plate model as a function of Knudsen number. It was concluded that the parallel plate model is adequate for making engineering analyses. The influence of all parameters, except layer density, is well represented by the model. Representation of the influence of layer density is less satisfactory, but can be improved by modification of the flat plate model to allow for the more obvious practical nonidealities, such as crinkling, or the presence of a net spacer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 19; Jan. 198
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    Turbulent flow in a square-to-round transition (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Measurements of turbulent flow in a duct with a cross sectional transition from square to round are presented. Laser Doppler velocimetry was used to measure the mean velocity components, turbulence levels and shear stresses. The boundary layers at the inlet and exit of the transition were approximately 13 percent and 20 percent of the hydraulic diameter respectively, becoming thicker near the corner fillets. The development of secondary flow, of magnitudes up to 7 percent of the bulk velocity is shown. This flow is directed away from the corner fillets and along the periphery of the duct and is associated with the longitudinal curvature of the wall and the related pressure gradients.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-3447 , FS-80-30
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    Dynamic behavior of an unsteady trubulent boundary layer (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Experiments on an unsteady turbulent boundary layer are reported in which the upstream portion of the flow is steady (in the mean) and in the downstream region, the boundary layer sees a linearly decreasing free stream velocity. This velocity gradient oscillates in time, at frequencies ranging from zero to approximately the bursting frequency. For the small amplitude, the mean velocity and mean turbulence intensity profiles are unaffected by the oscillations. The amplitude of the periodic velocity component, although as much as 70% greater than that in the free stream for very low frequencies, becomes equal to that in the free stream at higher frequencies. At high frequencies, both the boundary layer thickness and the Reynolds stress distribution across the boundary layer become frozen. The behavior at higher amplitude is quite similar. At sufficiently high frequencies, the boundary layer thickness remains frozen at the mean value over the oscillation cycle, even though flow reverses near the wall during a part of the cycle.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-81304 , A-8640 , USAAVRADCOM-TR-81-B-17 , REPT-992-21-01
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