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  • FLUID MECHANICS AND HEAT TRANSFER  (2,457)
  • 1985-1989  (2,457)
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  • 1
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    Characteristic features of the operation of high-temperature heat pipes with a noncondesable gas (1987)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The principal concepts related to the nature of the processes occurring in high-temperature heat pipes with a noncondensable gas are examined, and guidelines for the development of such heat pipes are presented. The discussion is illustrated by experimental results obtained for a horizontal sodium heat pipe (diameter, 18/1 mm; length, 710 mm). In particular, attention is given to the starting dynamics and mechanisms, the shape of the vapor-gas front, and the vapor-gas front velocity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20015 , NAS 1.77:20015
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  • 2
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    Analysis method for the production of Reynolds stresses in compressible turbulent flow (fluid mechanics) (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A geometrical interpretation of the grouping and variation rate terms of Reynolds stresses in compressible turbulent flow is presented. Examples of applications of the method are also given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20330 , NAS 1.77:20330
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  • 3
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    Studies on pressure response of gas bubbles contributions of condensed droplets in bubbles generated by a uniform nucleation (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The response of a tiny gas bubble under reduced pressure is investigated in its relation to cavitation. Equations of motion are formulated for gas mixtures inside the bubble and numerical calculations performed for several examples. The conclusions are as follows: (1) at the onset of bubble growth, the gas mixture inside it adiabatically expands and the temperature decreases. Condensed droplets appear inside the gas mixture due to a uniform nucleation and the temperature recovers, thus the motion of the bubble is apparently isothermal; (2) the evaporation and condensation coefficient largely affects bubble motions (maximum radius, period and rate of attenuation of the bubble oscillation) including the uniform contraction; (3) the oscillation period of the bubble is longer as the equilibrium bubble radius is larger when the surrounding pressure decreases stepwise. In this circumstance the temperature inside the bubble is kept constant due to condensation evaporation phenomena and is nearly isothermal; and (4) when the surrounding pressure decreases in a stepwise fashion, the critical pressure bubble radius relation becomes closer to that for the isothermal process if the bubble radius is larger than 8 microns.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20343 , NAS 1.77:20343
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  • 4
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    Heat transfer during the boiling of liquids in heat pipe wicks (1987)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Data in the literature on heat transfer in the case of nucleate boiling of various liquids in the wicks of heat pipes are reviewed. It is shown that none of the known analytical relationships can be used to generalize, with sufficient accuracy, the experimental data found in the literature. It is further shown that the exponent of the specific heat flux in the heat transfer law changes as a function of the liquid and wick properties. A relationship is obtained which generalizes experimental data for heat transfer agents of moderate temperatures (water, acetone, ethanol, and R-11 and R-113 coolants) and ammonia.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20108 , NAS 1.77:20108
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  • 5
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    Transitional Boundary Layers Under the Influence of High Free Stream Turbulence, Intensive Wall Cooling and High Pressure Gradients in Hot Gas Circulation (1987)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The requirements for fundamental experimental studies of the influence of free stream turbulence, pressure gradients and wall cooling are discussed. Under turbine-like free stream conditions, comprehensive tests of transitional boundary layers with laminar, reversing and turbulent flow increments were performed to decouple the effects of the parameters and to determine the effects during mutual interaction.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88524 , NAS 1.15:88524
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  • 6
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    Hypersonic aerothermodynamics status report (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: This survey paper gives an overview of NASA's Aerothermodynamics program. The purpose is to present the elements of, example results from, and projected technology needs for hypersonic fluid and thermal physics. The NASA program is focused on improving the fundamental understanding of aerodynamic and aerothermodynamic flow phenomena over hypersonic vehicles operating in the continuum, transitional, and free molecule flow regime. Vehicle design capabilities, computational fluid dynamics, computational chemistry, turbulence modeling, aerothermal loading, Shuttle Orbiter flight data analysis, and aerothermal facilities are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 7
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    Propagation of detonations in hydrazine vapor (1985)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: In the range of greater hydrazine vapor pressure, detonation speed depends exclusively on the extent of the ammonia decomposition in the second reaction stage. As vapor pressure decreases, the ammonia disintegration speed becomes increasingly slower and the reaction reached in the reaction zone increasingly decreases until finally, in the vapor pressure range between 53 and 16 Torr, the contribution of the second stage to detonation propagation disappears, and only the first stage remains active. Since the disintegration speed of the hydrazine in this pressure range has decreased markedly as well, no level, but rather only spinning, detonations occur. Temporary separations of the impact front and the reaction zone in the process lead to fluctuations of the detonation speed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77922 , NAS 1.15:77922
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  • 8
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    Laminar boundary layer in conditions of natural transition to turbulent flow (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Results of experimental study of regularities of a natural transition of a laminar boundary layer to a turbulent layer at low subsonic air flow velocities are presented, analyzed and compared with theory and model experiments.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77985 , NAS 1.15:77985
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  • 9
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    Semiempirical methods for computing turbulent flows (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Two semiempirical theories which provide a basis for determining the turbulent friction and heat exchange near a wall are presented: (1) the Prandtl-Karman theory, and (2) the theory utilizing an equation for the energy of turbulent pulsations. A comparison is made between exact numerical methods and approximate integral methods for computing the turbulent boundary layers in the presence of pressure, blowing, or suction gradients. Using the turbulent flow around a plate as an example, it is shown that, when computing turbulent flows with external turbulence, it is preferable to construct a turbulence model based on the equation for energy of turbulent pulsations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77996 , NAS 1.15:77996
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  • 10
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    Measurement of heat-transfer coefficients in shock wave-turbulent boundary layer interaction regions with a multi-layered thin film heat transfer gauge (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A thin film heat transfer gauge is applied to the measurement of heat transfer coefficients in the interaction regions of incident shock waves and fully developed turbulent boundary layers. It was developed to measure heat flux with high spatial resolution and fast response for wind tunnels with long flow duration. To measure the heat transfer coefficients in the interaction region in detail, experiments were performed under the conditions of Mach number = 4, total pressure = 1.2 MPa, 0.59 to approximately 0.65. Reynolds number = 1.3 to approximately 1.5 x 10 to the 7th power and incident shock angles from 17.8 to 22.8 degrees. The results show that the heat transfer coefficient changes complicatedly in the interaction region. At the beginning the interaction region, the heat transfer coefficient decreases at first, reaches its minimum value at the point where the pressure begins to increase, and then increases sharply. When the boundary layer begins to separate, even a small separation bubble causes significant changes in the heat transfer coefficient, while the pressure does not show any changes which suggests that the boundary layer begins to separate.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77958 , NAS 1.15:77958
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  • 11
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    Heat transfer in pipes (1985)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The heat transfer from hot water to a cold copper pipe in laminar and turbulent flow condition is determined. The mean flow through velocity in the pipe, relative test length and initial temperature in the vessel were varied extensively during tests. Measurements confirm Nusselt's theory for large test lengths in laminar range. A new equation is derived for heat transfer for large starting lengths which agrees satisfactorily with measurements for large starting lengths. Test results are compared with the new Prandtl equation for heat transfer and correlated well. Test material for 200- and to 400-diameter test length is represented at four different vessel temperatures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77838 , NAS 1.15:77838
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  • 12
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    Generation and development of small-amplitude disturbances in a laminar boundary layer in the presence of an acoustic field (1985)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A low-turbulence subsonic wind tunnel was used to study the influence of acoustic disturbances on the development of small sinusoidal oscillations (Tollmien-Schlichting waves) which constitute the initial phase of turbulent transition. It is found that acoustic waves propagating opposite to the flow generate vibrations of the model (plate) in the flow. Neither the plate vibrations nor the acoustic field itself have any appreciable influence on the stability of the laminar boundary layer. The influence of an acoustic field on laminar boundary layer disturbances is limited to the generation of Tollmien-Schlichting waves at the leading-edge of the plate.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77826 , NAS 1.15:77826
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  • 13
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    Determination of the specific area of liquid gas and the velocity of weak pressure waves in aqueous foams (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: The specific area of an aqueous foam contained in a tube is obtained by determining the fraction of the quantity of light emitted by a source and diffused by the specific area of the column of the foam. The velocity of the waves of weak pressure (which propagate in the air with the velocity of sound) is measured by noticing the moment when the wave penetrates the column and the moment when, having reached the opposite side, it determines a variation of the light diffused by the area of the latter.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20347 , NAS 1.77:20347
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  • 14
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    Conservative boundary conditions for 3D gas dynamics problems (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: A method is described for 3D-gas dynamics computer simulation in regions of complicated shape by means of nonadjusted rectangular grids providing unified treatment of various problems. Some test problem computation results are given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88487 , NAS 1.15:88487
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  • 15
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    Heat and mass transfer in a dissociated laminar boundary layer of air with consideration of the finite rate of chemical reaction (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: A numerical investigation of heat and mass transfer in a dissociated laminar boundary layer of air on an isothermal flat plate is carried out for different degrees of cooling of the wall. A finite-difference chemical model is used to study elementary reactions involving NO2 and N2O. The analysis is based on equations of continuity, momentum, energy, conservation and state for the two-dimensional viscous flow of a reacting multicomponent mixtures. Attention is given to the effects of both catalyticity and noncatalyticity of the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-78001 , NAS 1.15:78001 , Heat and Mass Transfer All-Union Conference, Minsk; May 17, 1976 - May 20, 1976; Belorussian; USSR
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  • 16
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    Numerical simulation of vortex breakdown (1985)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: The breakdown of an isolated axisymmetric vortex embedded in an unbounded uniform flow is examined by numerical integration of the complete Navier-Stokes equations for unsteady axisymmetric flow. Results show that if the vortex strength is small, the solution approaches a steady flow and the vortex is stable. If the strength is large enough, the solution remains unsteady and a recirculating zone will appear near the axis, its form and internal structure resembling those of the axisymmetric breakdown bubbles with multi-cells observed by Faler and Leibovich (1978). For apppropriate combinations of flow parameters, the flow reveals quasi-periodicity. Parallel calculations with the quasi-cylindrical approximation indicate that so far as predicting of breakdown is concerned, its results coincide quite well with the results mentioned above. Both show that the vortex breakdown has little concern with the Reynolds number or with the critical classification of the upstream flow, at least for the lower range of Reynolds numbers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77951 , NAS 1.15:77951
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  • 17
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    Designs of profiles for cascades (1988)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: Optimized cascade profiles for arbitrary applications were designed. The influence of Mach number, Reynolds number, and degree of turbulence were taken into account. The optimization aimed at maximum pressure increase, minimum pressure loss, low Reynolds number dependence, or large angle-of-attack range. Starting from the boundary layer form parameter distribution (by which transition point and separation point can be controlled) the velocity distribition and the contour were calculated. The profile characteristics were tested off-design and were improved. Interferometric measurements were performed in the transonic cascade channel.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20161 , NAS 1.77:20161
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  • 18
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    Some problems of the theory of bubble growth and condensation in bubble chambers (1988)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: This work is an attempt to explain the reasons for the discrepancies between the theoretical and experimental values of bubble growth rate in an overheated liquid, and to provide a brief formulation of the main premises of the theory on bubble growth in liquid before making a critical analysis. To simplify the problem, the floating upward of bubbles is not discussed; moreover, the study is based on the results of the theory of the behavior of fixed bubbles.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20232 , NAS 1.77:20232 , JINR-P-13-3726
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  • 19
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    A device for generating motive force through the expansion of a non-elastic dense fluid (1985)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: A device for generating motive force through the expansion of a dense, nonelastic fluid is described. It consists of an exterior block of a material with a low expansion coefficient, the interior of which is equipped with two circular cavities, both of which are equipped with rotors having blades constantly stressed outward by springs, so that they make contact with the cavity walls. One cavity is heated externally, and both have an exterior wall made of a friction ring which keeps the volume constant when their length varies. These cavities are interconnected by ducts which, at the inlet, are a prolongation of a peripheral groove made in the friction ring. The excess fluid produced by expansion flows through the groove, subsequently entering the cavity again after passing through a cooler located in the exterior part of the block. Both rotors are connected to gears with appropriate ratios which are equipped with a blocking device to guarantee that they always rotate in the same direction.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77664 , NAS 1.15:77664
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  • 20
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    Characteristics of heat exchange in the region of injection into a supersonic high-temperature flow (1985)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: An experimental investigation of the local heat transfer coefficient distribution during gas injection into the supersonic-flow portion of a Laval nozzle is discussed. The controlling dimensionless parameters of the investigated process are presented in terms of a generalized relation for the maximum value of the heat transfer coefficient in the nozzle cross section behind the injection hole. Data on the heat transfer coefficient variation along the nozzle length as a function of gas injection rate are also presented, along with the heat transfer coefficient distribution over a cross section of the nozzle.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77833 , NAS 1.15:77833
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  • 21
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    Self-adaptive difference method for the effective solution of computationally complex problems of boundary layer theory (1986)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: An implicit difference procedure for the solution of equations for a chemically reacting hypersonic boundary layer is described. Difference forms of arbitrary error order in the x and y coordinate plane were used to derive estimates for discretization error. Computational complexity and time were minimized by the use of this difference method and the iteration of the nonlinear boundary layer equations was regulated by discretization error. Velocity and temperature profiles are presented for Mach 20.14 and Mach 18.5; variables are velocity profiles, temperature profiles, mass flow factor, Stanton number, and friction drag coefficient; three figures include numeric data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88440 , NAS 1.15:88440 , DGLR-76-185 , Sep 14, 1976 - Sep 16, 1976; Munich; Germany
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  • 22
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    Development of perturbations in the boundary layer (1986)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: The transition of laminar flows into turbulent flows in a boundary layer is discussed. The individual aspects of the transition process, observed under controllable model conditions are examined. The aspect of this problem, namely the development or excitation of the natural oscillations in the boundary layer, the so-called Tollmin-Schlichting waves is covered. Three types of excitation of these waves are considered: (1) distributed generation throughout the boundary layer; (2) generation in the vicinity of the forward edge of a model, having either a sharp edge or an edge with a large radius or curvature, and (3) generation in a developed boundary layer by means of a focused effect.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77986 , NAS 1.15:77986
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  • 23
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    Contribution to the theory of stationary separation areas (1985)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: An attempt is made to determine the region of existence of possible steady flows with a closed separation area in a range of Reynolds numbers such that flow in the viscous mixing area can be described by the Prandtl's equations. The boundary conditions for the flow in the separation region are selected so as to simplify the flow pattern in this region, making it possible to use the methods of hydrodynamic analysis. A rule for determining stable steady flows with separation areas is formulated which is well suited for analyzing laminar flows and can be applied to turbulent flows in some areas.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77825 , NAS 1.15:77825
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  • 24
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    Stability of an oscillating boundary layer (1985)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: Levchenko and Solov'ev (1972, 1974) have developed a stability theory for space periodic flows, assuming that the Floquet theory is applicable to partial differential equations. In the present paper, this approach is extended to unsteady periodic flows. A complete unsteady formulation of the stability problem is obtained, and the stability characteristics over an oscillating period are determined from the solution of the problem. Calculations carried out for an oscillating incompressible boundary layer on a plate showed that the boundary layer flow may be regarded as a locally parallel flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77827 , NAS 1.15:77827
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  • 25
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    A Study of Flow Separation in Transonic Flow Using Inviscid and Viscous Computational Fluid Dynamics (CFD) Schemes (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: A comparison of flow separation in transonic flows is made using various computational schemes which solve the Euler and the Navier-Stokes equations of fluid mechanics. The flows examined are computed using several simple two-dimensional configurations including a backward facing step and a bump in a channel. Comparison of the results obtained using shock fitting and flux vector splitting methods are presented and the results obtained using the Euler codes are compared to results on the same configurations using a code which solves the Navier-Stokes equations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-183119 , NAS 1.26:183119 , ODU/ICAM-88-102
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  • 26
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    Numerical Solution of the Incompressible Navier-Stokes Equations in Three-dimensional Generalized Curvilinear Coordinates (1986)
    In:  CASI
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    Publication Date: 2019-08-14
    Description: Numerically solving the incompressible Navier-Stokes equations is known to be time consuming and expensive. Testing of the INS3D computers code, which solves these equations with the use of the pseudocompressibility method, shows this method to be an efficient way to obtain the steady state solution. The effects of the waves introduced by the pseudocompressibility method are analyzed and criteria are set and tested for the choice of the pseudocompressibility parameter which governs the artificial sound speed. The code is tested using laminar flow over a two dimensional backward-facing step, and laminar flow over a two dimensional circular cylinder. The results of the computations over the backward-facing step are in excellent agreement with experimental results. The transient solution of the flow over the cylinder impulsively started from rest is in good agreement with experimental results. However, the computed frequency of periodic shedding of vortices behind the cylinder is not in agreement with the experimental value. For a three dimensional test case, computations were conducted for a cylinder end wall junction. The saddle point separation and horseshoe vortex system appear in the computed field. The solution also shows secondary vortex filaments which wrap around the cylinder and spiral up in the wake.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-86840 , A-85413 , NAS 1.15:86840
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  • 27
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    A New Finite Element Approach for Prediction of Aerothermal Loads: Progress in Inviscid Flow Computations (1985)
    In:  CASI
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    Publication Date: 2019-08-14
    Description: Recent progress in the development of finite element methodology for the prediction of aerothermal loads is described. Two dimensional, inviscid computations are presented, but emphasis is placed on development of an approach extendable to three dimensional viscous flows. Research progress is described for: (1) utilization of a commerically available program to construct flow solution domains and display computational results, (2) development of an explicit Taylor-Galerkin solution algorithm, (3) closed form evaluation of finite element matrices, (4) vector computer programming strategies, and (5) validation of solutions. Two test problems of interest to NASA Langley aerothermal research are studied. Comparisons of finite element solutions for Mach 6 flow with other solution methods and experimental data validate fundamental capabilities of the approach for analyzing high speed inviscid compressible flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-86434 , NAS 1.15:86434 , AIAA PAPER 85-1533-CP
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  • 28
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    Further Improvements to Nozzle Boundary Layer Calculations in BLIMPJ (1989)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Further improvements made to advance the current Boundary Layer Integral Matrix Procedure - Version J (BLIMPJ) containing previously modeled simplified calculation methods by accounting for condensed phase, thick boundary layer and free stream turbulence effects are discussed. The condensed phase effects were included through species composition effect considered via input to the code and through particle damping effect considered via a turbulence model. The thrust loss calculation procedure for thick boundary layer effects was improved and the optimization of net thrust with respect to nozzle length was performed. The effects of free stream turbulence were approximately modeled in the turbulence model.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JHU, The 26th JANNAF Combustion Meeting, Volume 2; p 311-325|26th JANNAF Combustion Meeting; Oct 23, 1989 - Oct 27, 1989; Pasadena, CA; United States
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  • 29
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    Liquid Behavior at Critical and Supercritical Conditions (1989)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: At a JANNAF workshop, the issue of fluids at and above the critical point was discussed to obtain a better understanding of similar conditions in combustion chambers of rocket engines. Invited experts from academic, industrial, and government institutions presented the most recent physical, numerical, and experimental advances. During the final discussion period, it was agreed that: (1) no analytical capability exists to simulate subject conditions; (2) mechanisms reflected by opalescence, the solubility of gases, other interfacial phenomena listed, and fluorescence diagnostics are new and important; (3) multicomponent mixtures, radiation, critical fluctuation, and other recorded ones pose unknown effects; and (4) various identified analytical and experimental actions must be initiated in a mutually supporting sequence.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 26th JANNAF Combustion Meeting; Oct 23, 1989 - Oct 27, 1989; Pasadena, CA; United States|JHU, The 26th JANNAF Combustion Meeting, Volume 2; p 335-342
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  • 30
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    The theory of flotation (1988)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: A brief summary of the fundamentals of the Linear theory of flotation is given. The theory by no means contradicts the previous Laminar theory or even the thermodynamics (Wark-Siedler), rather it is a refinement of the known Hardy-Langmuir-Harkin conceptions for the case when there are not two phases and phase boundaries, but rather three phases and corresponding phase boundary edges. The appearance of such three-phase boundaries (ore, water, air) is characteristic for modern flotation methods.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TT-20278 , NAS 1.77:20278
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    Experimental studies on the stability and transition of 3-dimensional boundary layers (1987)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: Three-dimensional unstable boundary layers were investigated as to their characteristic instabilities, leading to turbulence. Standing cross-flow instabilities and traveling waves preceding the transition were visualized with the hydrogen bubble technique in the boundary layer above the wall of a swept cylinder. With the sublimation method and hot film technique, a model consisting of a swept flat plate with a pressure-inducing displacement body in the 1 m wind tunnel was studied. Standing waves and traveling waves in a broad frequency are observed. The boundary layer of this model is close to the assumptions of the theory.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-88539 , NAS 1.15:88539 , DFVLR-FB-86-24
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    Spacelab 3 Mission Science Review (1987)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: Papers and abstracts of the presentations made at the symposium are given as the scientific report for the Spacelab 3 mission. Spacelab 3, the second flight of the National Aeronautics and Space Administration's (NASA) orbital laboratory, signified a new era of research in space. The primary objective of the mission was to conduct applications, science, and technology experiments requiring the low-gravity environment of Earth orbit and stable vehicle attitude over an extended period (e.g., 6 days) with emphasis on materials processing. The mission was launched on April 29, 1985, aboard the Space Shuttle Challenger which landed a week later on May 6. The multidisciplinary payload included 15 investigations in five scientific fields: material science, fluid dynamics, life sciences, astrophysics, and atmospheric science.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CP-2429 , M-547 , NAS 1.55:2429
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  • 33
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    Studies of acoustic effects on a flow boundary layer in air (1986)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: Effects of sound fields on the flow boundary layer on a flat plate subjected to a parallel flow are studied. The boundary layer is influenced by controlling the stagnation point flow at the front edge of the plate. Depending on the Reynolds number and sound frequency, excitation or suppression of turbulent is observed. Measurements were taken at wind velocities between 10 and 30 m/sec and sound frequencies between 0.2 and 3.0 kHz.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77981 , NAS 1.15:77981
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  • 34
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    The volume change during solidification (1985)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: The liquid-solid phase transformation of solidifying metallic melts is accompanied by a volume change Delta-Vm. This volume change produces a gravity-independent microscopic flow near the solidification front. In a ground-based laboratory, solidification processes are also affected by convection due to temperature and concentration gradients. A quantitative evaluation of the effects of these flows on the formation of structure requires reproducible values of Delta-Vm. Alloys with Delta-Vm = 0 would be best suited for such an evaluation, while alloys with a constant value for Delta-Vm are still usable. Another requirement is related to a solidus-liquidus interval which is as small as possible. One-phase alloys, which would be particularly well suited, could not be found. For these reasons, alloys which solidify in two phases, as for example eutectics, have been considered, taking into account the Al-Ge system. Attention is given to the volume change at the melting point, the measurement of this change, the volume change at solidification, and applications to terrestrial technology.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-77817 , NAS 1.15:77817 , Spacelab Utilization: Mater. Res. and Technol. in Space; Seminar on Current Status; Oct 04, 1982 - Oct 06, 1982; Bonn; Germany
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    Comparison between pressure gradient method and MAC method on high Re calculation (1989)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: A cavity flow driven by shear and buoyancy forces is used as a test problem in the application of a nonstaggered pressure gradient (PG) method in solving the two-dimensional incompressible Navier-Stokes equations. Twelve finite differencing schemes are used to solve the cavity flow problem. The schemes consist of various combinations of grid arrangements, upwinding treatments, and conservativeness of convection terms. An artificial source term is introduced, and the solutions are compared with those obtained by the conventional marker-and-cell (MAC) method. The comparisons favor the PG method. Numerical results obtained by the twelve schemes are compared with exact solutions in order to assess the stability and accuracy of each scheme.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Symposium on Numerical Methods in Engineering; Sept. 11-15, 1989; Lausanne; Switzerland
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  • 36
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    A spectral multi-domain technique applied to stability and transition of incompressible and compressible flows (1989)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Techniques for the numerical simulation of compressible and incompressible viscous flows are described and demonstrated. The focus is on a multidomain spectral method based on the flux-balance domain-interface scheme of Macaraeg and Streett (1986). The fundamental principles of the method are reviewed, and it is shown that the multidomain spectral approach facilitates the treatment of instability and the transition to turbulence. Typical numerical results for the Taylor-Couette problem and for bounded compressible high-speed mixing layers are presented in graphs and briefly characterized.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Symposium on Numerical Methods in Engineering; Sept. 11-15, 1989; Lausanne; Switzerland
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    Advanced computational techniques for hypersonic propulsion (1989)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Computational Fluid Dynamics (CFD) has played a major role in the resurgence of hypersonic flight, on the premise that numerical methods will allow performance of simulations at conditions for which no ground test capability exists. Validation of CFD methods is being established using the experimental data base available, which is below Mach 8. It is important, however, to realize the limitations involved in the extrapolation process as well as the deficiencies that exist in numerical methods at the present time. Current features of CFD codes are examined for application to propulsion system components. The shortcomings in simulation and modeling are identified and discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Symposium on Air Breathing Engines; Sept. 3-8, 1989; Athens; Greece
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  • 38
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    Near wall flow parameters in the blade end-wall corner region (1989)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The effects of secondary end-wall corner flows on near wall flow parameters in turbomachinary are studied. Important near wall flow parameters such as the wall shear stress vector, the mean wall pressure, the wall pressure fluctuations, and the correlation of the wall pressure fluctuation with the velocity fluctuation in three-dimensional turbulent flows are first experimentally investigated. The blade end-wall corner region is simulated by mounting airfoil section of symmetric blades on both sides of the flat plate with semicircular leading edge. Observed changes in the maximum values of the wall shear stress and its location from the corner line could be associated with the streching and attenuation of the horseshoe vortex. The values of wall pressure fluctuation intensity in the blade end-wall corner region are found to be influenced by the changes of the strength of the horseshoe vortex. The correlation of the wall pressure fluctuation with the velocity fluctuation indicated higher values of correlation coefficient in the inner region as compared to the outer region of the shear layer. The values of wall pressure-velocity correlation coefficient in the blade end-wall corner region also decrease in the streamwise direction while increasing in the presence of favorable and adverse pressure gradients.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Symposium on Air Breathing Engines; Sept. 3-8, 1989; Athens; Greece
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  • 39
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    Finite element solution of the Euler equations in two and three dimensions (1988)
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    Publication Date: 2019-07-27
    Description: The paper presents a finite element procedure for solving the equations of compressible flow over bodies of arbitrary geometry. The numerical solution algorithm employed is an explicit two-step version of a second order Taylor-Galerkin scheme. The discretization of the computational domain into unstructured meshes of triangles in two dimensions and tetrahedra in three dimensions is performed by an automatic mesh generator. In the approach, the mesh generator is coupled to the finite element solver to produce an adaptive remeshing procedure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: GAMM-Conference on Numerical Methods in Fluid Mechanics; Sept. 9-11, 1987; Louvain-la-Neuve; Belgium
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  • 40
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    Comparative study of high-resolution shock-capturing schemes for a real gas (1988)
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    Publication Date: 2019-07-27
    Description: Recently developed second-order explicit shock-capturing methods, in conjunction with generalized flux-vector splittings, and a generalized approximate Riemann solver for a real gas are studied. The comparisons are made on different one-dimensional Riemann (shock-tube) problems for equilibrium air with various ranges of Mach numbers, densities and pressures. Six different Riemann problems are considered. These tests provide a check on the validity of the generalized formulas, since theoretical prediction of their properties appears to be difficult because of the non-analytical form of the state equation. The numerical results in the supersonic and low-hypersonic regimes indicate that these produce good shock-capturing capability and that the shock resolution is only slightly affected by the state equation of equilibrium air. The difference in shock resolution between the various methods varies slightly from one Riemann problem to the other, but the overall accuracy is very similar. For the one-dimensional case, the relative efficiency in terms of operation count for the different methods is within 30 percent. The main difference between the methods lies in their versatility in being extended to multidimensional problems with efficient implicit solution procedures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: GAMM-Conference on Numerical Methods in Fluid Mechanics; Sept. 9-11, 1987; Louvain-la-Neuve; Belgium
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  • 41
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    What happens to the large eddies when net drag reduction is achieved by outer flow manipulators? (1987)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The tandem-arranged parallel plate manipulator (TAPPM) presently used to generate a flow with net drag reduction is conditionally sampled and found to exhibit significant changes of the boundary layer's large-scale motions at 20 delta(0), where delta(0) is the boundary layer thickness at the upstream plate of the TAPPM. Flow fields in the 'valleys' are equally affected. Both turbulent and irrotational flows then reestablish themselves by 50 delta(0). Flow visualization indicates that the TAPPM wake is very coherent at 20 delta(0), and has not yet spread into the wall region, while large scale motions and the ambient response flow continue to exhibit dynamic changes. This indicates that the shielding effect of the TAPPM's wake prolongs suppression of large-scale motions, thereby reducing skin friction over a sufficiently long extent of the boundary layer to overcome device drag and yield net drag reductions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbulent drag reduction by passive means; Sept. 15-17, 1987; London
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  • 42
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    Turbulence structure at high shear rate (1987)
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    Publication Date: 2019-07-27
    Description: The structure of homogeneous turbulence in the presence of a high shear rate is studied using results obtained from three-dimensional time-dependent numerical simulations of the Navier-Stokes equations on a grid of 512 x 128 x 128 node points. It is shown that high shear rate enhances the streamwise fluctuating motion to such an extent that a highly anisotropic turbulence state with a one-dimensional velocity field and two-dimensional small-scale turbulence develops asymptotically as total shear increases. Instantaneous velocity fields show that high shear rate in homogeneous turbulent shear flow produces structures which are similar to the streaks present in the viscous sublayer of turbulent boundary layers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Rotordynamic forces on centrifugal pump impellers (1987)
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    Publication Date: 2019-07-27
    Description: The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine). In each case, a destabilizing force was observed over a region of positive whirl.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Conference on Fluid Machinery; Sept. 1987; Budapest; Hungary
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  • 44
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    Near-wall k-epsilon turbulence modeling (1987)
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    Publication Date: 2019-07-27
    Description: The flow fields from a turbulent channel simulation are used to compute the budgets for the turbulent kinetic energy (k) and its dissipation rate (epsilon). Data from boundary layer simulations are used to analyze the dependence of the eddy-viscosity damping-function on the Reynolds number and the distance from the wall. The computed budgets are used to test existing near-wall turbulence models of the k-epsilon type. It was found that the turbulent transport models should be modified in the vicinity of the wall. It was also found that existing models for the different terms in the epsilon-budget are adequate in the region from the wall, but need modification near the wall. The channel flow is computed using a k-epsilon model with an eddy-viscosity damping function from the data and no damping functions in the epsilon-equation. These computations show that the k-profile can be adequately predicted, but to correctly predict the epsilon-profile, damping functions in the epsilon-equation are needed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Stochastic estimation of organized structures in turbulent channel flow (1987)
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    Publication Date: 2019-07-27
    Description: Linear stochastic estimation is used to approximate the conditional vector fields associated with high Reynolds stress producing events in numerically simulated turbulent channel flow. Joint probability density distributions of u-v are presented for y(+) between 1.35 and 180, and at each position the u-v values that make the greatest contributions to the average uv3 are used to define conditional ejection- and sweep-type events. In the y-z plane the conditional fields appear to be pairs of counter-rotating vortices. When the conditional event defined by the weighted probability density function is specified at a point close to the wall, the spacing and size of these eddies are consistent with the accepted wall streak spacing. As this point moves outwards, the eddy size increases significantly. An abrupt change in the flow angle occurs in the buffer layer and may indicate transition from streamwise oriented wall layer structures to hairpin vortices characterizing the outer layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Unsteady motion and transition to turbulence in developing curved duct flow (1987)
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    Publication Date: 2019-07-27
    Description: An experiment was performed to further the understanding of developing flows in curved ducts of square cross-section. Unlike most earlier works, attention was paid to investigating the time-dependent character of the motion. Mean and unsteady flow characteristics were determined using flow visualization and a laser-Doppler velocimeter. Only one velocity component, that aligned in the longitudinal (streamwise) coordinate direction, was measured. Notwithstanding, the time histories, autocorrelations and spectra derived reveal a time-periodic motion that becomes turbulent with increasing Reynolds number. The results are of intrinsic fundamental value and also illustrate the danger of imposing symmetry of the conservation equations on numerical solutions of this flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    An orthogonal decomposition of the axisymmetric jet mixing layer utilizing cross-wire velocity measurements (1987)
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    Publication Date: 2019-07-27
    Description: The structure of the mixing layer of the axisymmetric turbulent jet was investigated using cross-wire velocity measurements, which generated radial and streamwise cross-spectral data at eight radial positions and 25 azimuthal positions. The results show the existence of an azimuthal coherent ringlike structure dominated by axisymmetric mode near the potential core; however, from the center of the mixing layer out toward its low-speed side, the fourth, fifth, and sixth modes are dominating. A mechanism for the life cycle of coherent structures and for turbulence production in the axisymmetric jet mixing layer is proposed, which accounts for the observed phenomena and is amenable to dynamical analysis using the equations of motion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Unsteady diffuser vane pressure and impeller wake measurements in a centrifugal pump (1987)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Unsteady surface pressure measurements on a vaned diffuser of a centrifugal pump, and wake measurements of the flow exiting a centrifugal impeller into a vaneless diffuser are presented. Frequency spectra and ensemble averages are given for the unsteady measurements. Two different impellers were used, the pump impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine) and a two-dimensional impeller. The magnitude of the unsteady total pressure measured in the stationary frame at the impeller exit was found to be of the same order of magnitude as the total pressure rise across the pump. The magnitude of the unsteady diffuser vane pressures was observed to be significantly different on suction and pressure side of the vane, attaining its largest value on the suction side the leading edge while decreasing along the vane.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Conference on Fluid Machinery; Sept. 1987; Budapest; Hungary
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  • 49
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    Direct simulation of a turbulent oscillating boundary layer (1987)
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    Publication Date: 2019-07-27
    Description: The turbulent boundary layer driven by a freestream velocity that varies sinusoidally in time around a zero mean is considered. The flow has a rich behavior including strong pressure gradients, inflection points, and reversal. A theory for the velocity and stress profiles at high Reynolds number is formulated. Well-resolved direct Navier-Stokes simulations are conducted over a narrow range of Reynolds numbers, and the results are compared with the theoretical predictions. The flow is also computed over a wide range of Reynolds numbers using a new algebraic turbulence model; the results are compared with the direct simulations and the theory.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Transport of passive scalars in a turbulent channel flow (1987)
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    Publication Date: 2019-07-27
    Description: A direct numerical simulation of a turbulent channel flow with three passive scalars at different molecular Prandtl numbers is performed. Computed statistics including the turbulent Prandtl numbers are compared with existing experimental data. The computed fields are also examined to investigate the spatial structure of the scalar fields. The scalar fields are highly correlated with the streamwise velocity; the correlation coefficient between the temperature and the streamwise velocity is as high as 0.95 in the wall region. The joint probability distributions between the temperature and velocity fluctuations are also examined; they suggest that it might be possible to model the scalar fluxes in the wall region in a manner similar to the Reynolds stresses.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Measurements of time-dependent boundary layer turbulence in an oscillating flow (1987)
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    Publication Date: 2019-07-27
    Description: Changes in the time-dependent boundary-layer turbulence in an oscillating flow were investigated using the oscillating-flow facility described by Cook et al. (1985). Hot wire measurements were made across the boundary layer for frequencies ranging from 4 to 21 Hz at various positions from the boundary layer origin and with different amplitudes of velocity oscillation. The results clearly demonstrate that the turbulence level is influenced by the imposed oscillation. The variation of the turbulence level is not predicted well by the variation in boundary-layer thickness alone, indicating that the interaction between the imposed oscillation and the turbulence structure is more complex. It is suggested that turbulence models developed for steady flow may not be adequate for periodic turbulent flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    Study of Lagrangian characteristic times using direct numerical simulation of turbulence (1987)
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    Publication Date: 2019-07-27
    Description: Direct numerical simulations and large eddy simulations of homogeneous isotropic turbulence are used to compute Lagrangian statistics of turbulence and, in particular, its time scales. The computed time scales are compared with the spectral times scales that are frequently used in Eddy Damped Quasi-Normal Markovian calculations of the spectrum. The time scale models are rather good at high wavenumber and the results point to directions for improvement of the time scales at low wavenumber.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Sept. 7-9, 1987; Toulouse; France
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    A study of the temporal stability of multiple cell vortices (1989)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: The effect of initial mean velocity field on the stability characteristics of longitudinal vortices is documented in detail. The temporal stability of isolated multiple cell vortices is considered. The types of vortices studied include single cell as well as two and three cell vortices. It is shown that cell multiplicity in the vortex core has drastic effects on the stability characteristics. On the basis of numerical calculations, it is concluded that the growth rates of instabilities in multiple cell vortices are substantially larger (two to threefold increases are observed) than those of a single cell vortex. It is also determined that there is a substantial increase in the effective range of axial and azimuthal wavenumbers where instabilities are present. But most importantly, there is the appearance of a variety of viscous modes of instability. In the case of vortices, these latter instabilities which highlight the importance of viscous forces have never been reported before. These effects are discussed in detail for the case of a two cell vortex.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-4261 , NAS 1.26:4261
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    A conservative approach for flow field calculations on multiple grids (1988)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: In the computation of flow fields about complex configurations, it is very difficult to construct body-fitted coordinate systems. An alternative approach is to use several grids at once, each of which is generated independently. This procedure is called the multiple grids or zonal grids approach and its applications are investigated in this study. The method follows the conservative approach and provides conservation of fluxes at grid interfaces. The Euler equations are solved numerically on such grids for various configurations. The numerical scheme used is the finite-volume technique with a three-state Runge-Kutta time integration. The code is vectorized and programmed to run on the CDC VPS-32 computer. Some steady state solutions of the Euler equations are presented and discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-185313 , NAS 1.26:185313
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  • 55
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    Numerical methods for incompressible viscous flows with engineering applications (1988)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: A numerical scheme has been developed to solve the incompressible, 3-D Navier-Stokes equations using velocity-vorticity variables. This report summarizes the development of the numerical approximation schemes for the divergence and curl of the velocity vector fields and the development of compact schemes for handling boundary and initial boundary value problems.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-183143 , NAS 1.26:183143
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    Application of advanced grid generation techniques for flow field computations about complex configurations (1988)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: In the computation of flowfields about complex configurations, it is very difficult to construct a boundary-fitted coordinate system. An alternative approach is to use several grids at once, each of which is generated independently. This procedure is called the multiple grids or zonal grids approach; its applications are investigated. The method conservative providing conservation of fluxes at grid interfaces. The Euler equations are solved numerically on such grids for various configurations. The numerical scheme used is the finite-volume technique with a three-stage Runge-Kutta time integration. The code is vectorized and programmed to run on the CDC VPS-32 computer. Steady state solutions of the Euler equations are presented and discussed. The solutions include: low speed flow over a sphere, high speed flow over a slender body, supersonic flow through a duct, and supersonic internal/external flow interaction for an aircraft configuration at various angles of attack. The results demonstrate that the multiple grids approach along with the conservative interfacing is capable of computing the flows about the complex configurations where the use of a single grid system is not possible.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-183049 , NAS 1.26:183049
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    Low pressure gas flow analysis through an effusive inlet using mass spectrometry (1988)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A mass spectrometric method for analyzing flow past and through an effusive inlet designed for use on the tethered satellite and other entering vehicles is discussed. Source stream concentrations of species in a gaseous mixture are determined using a calibration of measured mass spectral intensities versus source stream pressure for standard gas mixtures and pure gases. Concentrations are shown to be accurate within experimental error. Theoretical explanations for observed mass discrimination effects as they relate to the various flow situations in the effusive inlet and the experimental apparatus are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-182712 , NAS 1.26:182712
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    Graphics and Flow Visualization of Computer Generated Flow Fields (1987)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Flow field variables are visualized using color representations described on surfaces that are interpolated from computational grids and transformed to digital images. Techniques for displaying two and three dimensional flow field solutions are addressed. The transformations and the use of an interactive graphics program for CFD flow field solutions, called PLOT3D, which runs on the color graphics IRIS workstation are described. An overview of the IRIS workstation is also described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-182679 , NAS 1.26:182679
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    Transient radiative energy transfer in incompressible laminar flows (1987)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Analysis and numerical procedures are presented to investigate the transient radiative interactions of nongray absorbing-emitting species in laminar fully-developed flows between two parallel plates. The particular species considered are OH, CO, CO2, and H2O and different mixtures of these. Transient and steady-state results are obtained for the temperaure distribution and bulk temperature for different plate spacings, wall temperatures, and pressures. Results, in general, indicate that the rate of radiative heating can be quite high during earlier times. This information is useful in designing thermal protection systems for transient operations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-182605 , NAS 1.26:182605
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    Numerical solutions of three-dimensional Navier-Stokes equations for closed-bluff bodies (1986)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Methods of grid adaption are reviewed and a method is developed with the capability of adaption to several flow variables. This method is based on a variational approach and is an algebraic method which does not require the solution of partial differential equations. The method has also been formulated in such a way that there is no need for any matrix inversion. The method is used in conjunction with the calculation of hypersonic flow over a blunt nose. The equations of motion are the compressible Navier-Stokes equations where all viscous terms are retained. They are solved by the MacCormack time-splitting method and a movie has been produced which shows simultaneously the transient behavior of the solution and the grid adaption. The results are compared with the experimental and other numerical results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-182359 , NAS 1.26:182359
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    Interaction of transient radiation in nongray gaseous systems (1987)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: A general formulation is presented to investigate the transient radiative interaction in nongray absorbing-emitting species between two parallel plates. Depending on the desired sophistication and accuracy, any nongray absorption model from line-by-line models to the wide band model correlations can be employed in the formulation to investigate the radiative interaction. Special attention is directed to investigate the radiative interaction in a system initially at a uniform reference temperature and suddenly the temperature of the bottom plate is reduced to a lower but constant temperature. The interaction is considered for the case of radiative equilibrium as well as for combined radiation and conduction. General as well as limiting forms of the governing equations are presented and solutions are obtained numerically by employing the method of variation of parameters. Specific results are obtained for CO, CO2, H2O, and OH. The information on species H2O and OH is of special interest for the proposed scramjet engine application. The results demonstrate the relative ability of different species for radiative interactions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-181389 , NAS 1.26:181389
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  • 62
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    Surface-slip equations for multicomponent, nonequilibrium air flow (1985)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-181252 , NAS 1.26:181252
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    Coupled flow, thermal and structural analysis of aerodynamically heated panels (1986)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: A finite element approach to coupling flow, thermal and structural analyses of aerodynamically heated panels is presented. The Navier-Stokes equations for laminar compressible flow are solved together with the energy equation and quasi-static structural equations of the panel. Interactions between the flow, panel heat transfer and deformations are studied for thin stainless steel panels aerodynamically heated by Mach 6.6 flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-180687 , NAS 1.26:180687
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    Enhanced viscous flow drag reduction using acoustic excitation (1987)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: Proper acoustic excitation of a single large-eddy break-up device can increase the resulting drag reduction and, after approximately 40 to 50 delta downstream, provide net drag reduction. Precise optimization of the input time delay, amplitude and response threshold is difficult but possible to achieve. Drag reduction is improved with optimized conditions. The possibility of optimized processing strongly suggests a mechanism which involves interaction of the acoustic waves and large eddies at the trailing edge of the large eddy break-up device. Although the mechanism for spreading of this phenomenon is unknown, it is apparent that the drag reduction effect does tend to spread spanwise as the flow convects downstream. The phenomenon is not unique to a particular blade configuration or flow velocity, although all data have been obtained at relatively low Reynolds numbers. The general repeatibility of the results for small configuration changes serves as verification of the phenomenon.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-180692 , NAS 1.26:180692
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  • 65
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    Stability of streamwise vortices (1987)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: A brief overview of some theoretical and computational studies of the stability of streamwise vortices is given. The local induction model and classical hydrodynamic vortex stability theories are discussed in some detail. The importance of the three-dimensionality of the mean velocity profile to the results of stability calculations is discussed briefly. The mean velocity profile is provided by employing the similarity solution of Donaldson and Sullivan. The global method of Bridges and Morris was chosen for the spatial stability calculations for the nonlinear eigenvalue problem. In order to test the numerical method, a second order accurate central difference scheme was used to obtain the coefficient matrices. It was shown that a second order finite difference method lacks the required accuracy for global eigenvalue calculations. Finally the problem was formulated using spectral methods and a truncated Chebyshev series.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-180566 , NAS 1.26:180566
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  • 66
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    Grid adaption for bluff bodies (1986)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Methods of grid adaptation are reviewed and a method is developed with the capability of adaptation to several flow variables. This method is based on a variational approach and is an algebraic method which does not require the solution of partial differential equations. Also the method was formulated in such a way that there is no need for any matrix inversion. The method is used in conjunction with the calculation of hypersonic flow over a blunt nose. The equations of motion are the compressible Navier-Stokes equations where all viscous terms are retained. They are solved by the MacCormack time-splitting method and a movie was produced which shows simulataneously the transient behavior of the solution and the grid adaptation. The results are compared with the experimental and other numerical results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-180329 , NAS 1.26:180329
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    Conduction investigations into the magnetic properties of matter (1986)
    In:  CASI
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    Publication Date: 2019-07-20
    Description: The thermal analysis of a heat exchanger for heating air to temperatures on the order of 3000 C for use in NASA's high temperature wind tunnel is presented. It was ascertained that an externally finned shell-and-tube type of heat exchanger with counterflow could be considered for this application. The methods of estimating the convective heat transfer coefficients are outlined in this report. As a part of thermal design the required size of heat exchanger was predicted. As a result of the extreme length required (approx. = 1/2 km), it was determined that a conventional heat exchanger may not be the most suitable tool for this application.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-179868 , NAS 1.26:179868
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    Numerical methods for turbulent flow (1988)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: It has generally become accepted that the Navier-Strokes equations predict the dynamic behavior of turbulent as well as laminar flows of a fluid at a point in space away form a discontinuity such as a shock wave. Turbulence is also closely related to the phenomena of non-uniqueness of solutions of the Navier-Strokes equations. These second order, nonlinear partial differential equations can be solved analytically for only a few simple flows. Turbulent flow fields are much to complex to lend themselves to these few analytical methods. Numerical methods, therefore, offer the only possibility of achieving a solution of turbulent flow equations. In spite of recent advances in computer technology, the direct solution, by discrete methods, of the Navier-Strokes equations for turbulent flow fields is today, and in the foreseeable future, impossible. Thus the only economically feasible way to solve practical turbulent flow problems numerically is to use statistically averaged equations governing mean-flow quantities. The objective is to study some recent developments relating to the use of numerical methods to study turbulent flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Hampton Inst., NASA/American Society for Engineering Educat; Hampton Inst., NASA(
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    The structure of pressure fluctuations in turbulent shear flows (1989)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Pressure fluctuations in a turbulent channel and a homogeneous shear flows are investigated by analyzing databases obtained from direct numerical simulations. Detailed statistics associated with the pressure fluctuations in both flows are discussed. Characteristics associated with the rapid (linear) and slow (nonlinear) pressure are examined. The global dependence of the pressure fluctuations and pressure-strain correlations are also examined by evaluating the integral associated with Green's function representations of them.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Symposium on Turbulent Shear Flows; Aug 21, 1989 - Aug 23, 1989; Stanford, CA; United States
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    Computational fluid dynamics - Current capabilities and directions for the future (1989)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including some of those not before understood. It is now being routinely applied to some rather complicated problems and starting to affect the design cycle of aerospace flight vehicles and their components. It is being used to complement, and is being complemented by, experimental studies. Several examples are presented in the paper to illustrate the current state of the art. Included is a discussion of the barriers to accomplishing the basic objective of numerical simulation. In addition, the directions for the future in the discipline of computational fluid dynamics are addressed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Supercomputing ''89; Nov 13, 1989 - Nov 17, 1989; Reno, NV; United States
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    Three-dimensional adaptive grid generation for body-fitted coordinate system (1988)
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    Publication Date: 2019-07-13
    Description: This report describes a numerical method for generating 3-D grids for general configurations. The basic method involves the solution of a set of quasi-linear elliptic partial differential equations via pointwise relaxation with a local relaxation factor. It allows specification of the grid spacing off the boundary surfaces and the grid orthogonality at the boundary surfaces. It includes adaptive mechanisms to improve smoothness, orthogonality, and flow resolution in the grid interior.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Intl. Conference on Numerical Grid Generation in Computational Fluid Mechanics ''88; Dec 05, 1988 - Dec 08, 1988; Miami Beach, FL; United States
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    Growth of randomness in a spatially developing wake (1989)
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    Publication Date: 2019-07-13
    Description: The spatially evolving vortical structures and randomness statistics at various downstream locations of a plane wake are examined. The growth of the continuous components of the power spectra in such a wake are systematically investigated. Selective amplification of the fundamental mode from the broadband noise is found in the linear region. The fundamental mode of large-magnitude locking in the wake suppresses the noise growth. When the wake is forced by large-amplitude random phase noise, nonlinear interactions of a few beating modes whose frequencies are close to the fundamental one play a crucial role in randomizing the wake. In this case, the vorticity contours show randomizing vortical structure of the wake. Pairing motion of the same-sign vortices is seen in the randomizing region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ISCFD Nagoya 1989; Aug 28, 1989 - Aug 31, 1989; Nagoya; Japan
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    Grids for DSMC computation of two and three-dimensional flows (1989)
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    Publication Date: 2019-07-13
    Description: Contemporary grid schemes for use in Direct Simulation Monte Carlo (DSMC) method of computing two- and three-dimensional flows are briefly surveyed. The grids described include: (1) simple, constant area cells defined by a rectangular grid; (2) multilevel rectangular grids; (3) adaptive rectangular cells; (4) 'point reference' scheme; (5) body-fitted 'analytical' cells; (6) 'general' schemes; (7) 'general' schemes with subcells; (8) orthogonal transformation to rectangular grid; (9) structural tetrahedral grids; (10) rectangular multilevel subcells with adaptive body-fitted cells.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ISCFD Nagoya 1989; Aug 28, 1989 - Aug 31, 1989; Nagoya; Japan
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    Numerical and experimental analysis of a thin liquid film on a rotating disk related to development of a spacecraft absorption cooling system (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The numerical and experimental analysis of a thin liquid film on a rotating and a stationary disk related to the development of an absorber unit for a high capacity spacecraft absorption cooling system, is described. The creation of artificial gravity by the use of a centrifugal field was focused upon in this report. Areas covered include: (1) One-dimensional computation of thin liquid film flows; (2) Experimental measurement of film height and visualization of flow; (3) Two-dimensional computation of the free surface flow of a thin liquid film using a pressure optimization method; (4) Computation of heat transfer in two-dimensional thin film flow; (5) Development of a new computational methodology for the free surface flows using a permeable wall; (6) Analysis of fluid flow and heat transfer in a thin film in the presence and absence of gravity; and (7) Comparison of theoretical prediction and experimental data. The basic phenomena related to fluid flow and heat transfer on rotating systems reported here can also be applied to other areas of space systems.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-183457 , NAS 1.26:183457 , National Heat Transfer Conference; Aug 01, 1989; Philadelphia, PA; United States
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    An improved algorithm for the modeling of vapor flow in heat pipes (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A heat pipe vapor flow algorithm suitable for use in codes on microcomputers is presented. The incompressible heat pipe vapor flow studies of Busse are extended to incorporate compressibility effects. The Busse velocity profile factor is treated as a function of temperature and pressure. The assumption of a uniform saturated vapor temperature determined by the local pressure at each cross section of the pipe is not made. Instead, a mean vapor temperature, defined by an energy integral, is determined in the course of the solution in addition to the pressure, saturation temperature at the wall, and the Busse velocity profile factor. For alkali metal working fluids, local species equilibrium is assumed. Temperature and pressure profiles are presented for several cases involving sodium heat pipes. An example for a heat pipe with an adiabatic section and two evaporators in sequence illustrates the ability to handle axially varying heat input. A sonic limit plot for a short evaporator falls between curves for the Busse and Levy inviscid sonic limits.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-185179 , E-5195 , NAS 1.26:185179 , International Heat Pipe Conference; May 21, 1990 - May 25, 1990; Minsk; USSR
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    Constitutive Relationships and Models in Continuum Theories of Multiphase Flows (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: In April, 1989, a workshop on constitutive relationships and models in continuum theories of multiphase flows was held at NASA's Marshall Space Flight Center. Topics of constitutive relationships for the partial or per phase stresses, including the concept of solid phase pressure are discussed. Models used for the exchange of mass, momentum, and energy between the phases in a multiphase flow are also discussed. The program, abstracts, and texts of the presentations from the workshop are included.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CP-3047 , M-616 , NAS 1.55:3047 , Apr 05, 1989 - Apr 07, 1989; Huntsville, AL; United States
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    High-resolution liquid-crystal heat-transfer measurements on the endwall of a turbine passage with variations in Reynolds number (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Local heat-transfer coefficients were experimentally mapped on the end-wall surface of a three-times turbine vane passage in a static, single-row cascade operated with room-temperature inlet air over a range of Reynolds numbers. The test surface was a composite of commercially available materials: a Mylar sheet with a layer of cholesteric liquid crystals, which change color with temperature, and a heater made of a polyester sheet coated with vapor-deposited gold, which produces uniform heat flux. After the initial selection and calibration of the composite sheet, accurate, quantitative, and continuous heat-transfer coefficients were mapped over the end-wall surface. The local heat-transfer coefficients (expressed as nondimensional Stanton number) are presented for inlet Reynolds numbers (based on vane axial chord) from 0.83 x 10(5) to 3.97 x 10(5).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME 1988 National Heat Transfer Conference; Jul 24, 1988 - Jul 27, 1988; Houston, TX; United States
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    A new hydrodynamic prediction of the peak heat flux from horizontal cylinders in low speed upflow (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Flow-boiling data have been obtained for horizontal cylinders in saturated acetone, isopropanol, and water, yielding heat flux vs. wall superheat boiling curves for the organic liquids. A region of low speed upflow is identified in which long cylindrical bubbles break off from the wake with regular frequency. The Strouhal number of bubble breakoff is a function only of the Froude number in any liquid, and the effective wake thickness in all liquids is a function of the density ratio and the Froude number. A low speed flow boiling burnout prediction procedure is presented which yields accurate results in widely dissimilar liquids.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME 1988 National Heat Transfer Conference; Jul 24, 1988 - Jul 27, 1988; Houston, TX; United States
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    The design and fabrication of a Stirling engine heat exchanger module with an integral heat pipe (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The conceptual design of a free-piston Stirling Space Engine (SSE) intended for space power applications has been generated. The engine was designed to produce 25 kW of electric power with heat supplied by a nuclear reactor. A novel heat exchanger module was designed to reduce the number of critical joints in the heat exchanger assembly while also incorporating a heat pipe as the link between the engine and the heat source. Two inexpensive verification tests are proposed. The SSE heat exchanger module is described and the operating conditions for the module are outlined. The design process of the heat exchanger modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pipe to transport heat to a Stirling engine are discussed. Similarly, the problems encountered when using a true heat pipe, as opposed to a more simple reflux boiler, are described. The instruments incorporated into the modules and the test program are also outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 1988 IECEC; Jul 31, 1988 - Aug 05, 1988; Denver, CO; United States
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    Effect of transition on oscillation flow losses in Stirling engine coolers and heaters (1988)
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    Publication Date: 2019-07-13
    Description: To improve the prediction of Stirling engine performance, a more realistic model of oscillating flow losses in tubular heat exchangers is necessary. An experimental investigation has therefore been initiated to determine the effects of flow oscillation on fluid mechanics and heat transfer in ducts. This paper presents the first velocity measurements taken in this investigation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 1988 IECEC; Jul 31, 1988 - Aug 05, 1988; Denver, CO; United States
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    Description of an oscillating flow pressure drop test rig (1988)
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    Publication Date: 2019-07-13
    Description: A test rig designed to generate heat exchanger pressure drop information under oscillating flow conditions is described. This oscillating flow rig is based on a variable stroke and variable frequency linear drive motor. A frequency capability of 120 hertz and a mean test pressure up to 15 mPA (2200 psi) allows for testing at flow conditions found in modern high specific power Stirling engines. An important design feature of this rig is that it utilizes a single close coupled dynamic pressure transducer to measure the pressure drop across the test sample. This eliminates instrumentation difficulties associated with the pressure sensing lines common to differential pressure transducers. Another feature of the rig is that it utilizes a single displacement piston. This allows for testing of different sample lengths and configurations without hardware modifications. All data acquisition and reduction for the rig is performed with a dedicated personal computer. Thus the overall system design efficiently integrates the testing and data reduction procedures. The design methodology and details of the test rig are described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: 1988 IECEC; Jul 31, 1988 - Aug 05, 1988; Denver, CO; United States
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    Study of three-dimensional effects on vortex breakdown (1988)
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    Publication Date: 2019-07-13
    Description: The incompressible axisymmetric steady Navier-Stokes equations in primitive variables are used to simulate vortex breakdown. The equations, discretized using a second-order, central-difference scheme, are linearized and then solved using an exact LU decomposition, Gaussian elimination, and Newton iteration. Solutions are presented for Reynolds numbers, based on vortex-core radius, as high as 1500. An attempt to study the stability of the axisymmetric solutions against three-dimensional perturbations is discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ICAS Congress; Aug 28, 1988; Jerusalem; Israel
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    Transient natural convection heat and mass transfer in a rectangular enclosure - A numerical analysis (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A numerical analysis of transient heat and solute transport across a rectangular cavity with combined horizontal temperature and concentration gradients is performed by a numerical method based on the SIMPLE. Numerical results show that the average Nusselt and Sherwood numbers both decrease markedly when the solutal and thermal buoyancy forces act in the opposite directions. When the solutal and thermal buoyancy forces act in the same directions, however, the average Sherwood number increases significantly and yet the average Nusselt number decreases slightly.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Southeastern Conference on Theoretical and Applied Mechanics; Apr 18, 1988 - Apr 19, 1988; Biloxi, MS; United States
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    Passive and active control of jet turbulence (1988)
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    Publication Date: 2019-07-13
    Description: Techniques for controlling the generation, growth, and interactions of large coherent structures in turbulent flows are discussed, reviewing the results of recent experimental investigations. The fundamental principles of active and passive coherent-structure manipulation are outlined; the effects of geometric modification are examined for the case of an elliptic jet; and particular attention is given to passive control via self-excitation, turbulence and noise suppression, control of pairing interaction via two-frequency excitation, and unsteady boundary-layer separation in wall jets. Diagrams and graphs of typical results are provided.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: IUTAM Symposium on Turbulence Management and Relaminarisation; Jan 13, 1987 - Jan 23, 1987; Bangalore; India
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    The mixing mechanism by organised turbulence structures in a plane jet excited by a novel method (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The effect on a plane subsonic turbulent jet of controlled high-amplitude periodic oscillations applied to the nozzle is investigated experimentally. A variable-speed motor and a gear-cam mechanism are used to make the lips of the nozzle reciprocate in opposite directions at the desired frequency. Velocity profiles, flow visualizations, and pressure-signal traces are presented and analyzed in detail. The complex vortex processes involved in the oscillation-induced spreading and entrainment of the jet are explored, and a critical Strouhal number for vortex formation and amplification is determined. The oscillation technique is found to augment the thrust of a jet/duct-diffuser configuration by a factor of 1.20; the thrust increases with oscillation frequency up to 20 Hz and remains constant if the frequency is further increased.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: IUTAM Symposium on Turbulence Management and Relaminarisation; Jan 13, 1987 - Jan 23, 1987; Bangalore; India
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    Numerical simulation of transition in a decelerating boundary layer (1988)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Transition in a decelerating flat-plate boundary layer is numerically simulated up to the beginning of three-dimensional breakdown, and the results are compared with an experiment. The adverse pressure gradient induced by deceleration increases the growth rate of disturbances and allows transition at lower Reynolds numbers. The primary instability is characterized by a wave packet, which undergoes three-dimensional distortion. Lambda vortices are locally observed, but they are not aligned with respect to the flow direction.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: IUTAM Symposium on Turbulence Management and Relaminarisation; Jan 13, 1987 - Jan 23, 1987; Bangalore; India
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    Workshop on Two-Phase Fluid Behavior in a Space Environment (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Workshop was successful in achieving its main objective of identifying a large number of technical issues relating to the design of two-phase systems for space applications. The principal concern expressed was the need for verified analytical tools that will allow an engineer to confidently design a system to a known degree of accuracy. New and improved materials, for such applications as thermal storage and as heat transfer fluids, were also identified as major needs. In addition to these research efforts, a number of specific hardware needs were identified which will require development. These include heat pumps, low weight radiators, advanced heat pipes, stability enhancement devices, high heat flux evaporators, and liquid/vapor separators. Also identified was the need for a centralized source of reliable, up-to-date information on two-phase flow in a space environment.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CP-3043 , REPT-89B00114 , NAS 1.55:3043 , Jun 13, 1988 - Jun 14, 1988; Ocean City, MD; United States
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  • 88
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    CFD in the context of IHPTET: The Integrated High Performance Turbine Technology Program (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Integrated High Performance Turbine Engine Technology (IHPTET) Program is an integrated DOD/NASA technology program designed to double the performance capability of today's most advanced military turbine engines as we enter the twenty-first century. Computational Fluid Dynamics (CFD) is expected to play an important role in the design/analysis of specific configurations within this complex machine. In order to do this, a plan is being developed to ensure the timely impact of CFD on IHPTET. The developing philosphy of CFD in the context of IHPTET is discussed. The key elements in the developing plan and specific examples of state-of-the-art CFD efforts which are IHPTET turbine engine relevant are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102132 , E-4868 , NAS 1.15:102132 , AIAA PAPER 89-2904 , Joint Propulsion Conference; Jul 10, 1989 - Jul 12, 1989; Monterey, CA; United States
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  • 89
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    Analysis of the transient compressible vapor flow in heat pipe (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-185119 , E-4945 , NAS 1.26:185119 , National Heat Transfer Conference; Aug 06, 1989 - Aug 09, 1989; Philadelphia, PA; United States
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  • 90
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    Unsteady stagnation-point heat transfer during passage of a concentrated vortex (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The unsteady boundary layer due to a single rectilinear vortex filament approaching a 2-D stagnation point is investigated. Assuming the vortex remains far from the surface, incompressible potential flow theory is used to determine the time dependent inviscid flow field. The unsteady boundary layer equations are solved by an alternating-direction-implicit finite-difference method. Two mechanisms which cause fluctuations in heat transfer are the unsteady velocity field in the boundary layer and secondly, the unsteady total temperature at the edge of the boundary layer. The relative importance of these mechanisms is dependent upon the total temperature fluctuations relative to the imposed temperature difference. As a vortex approaches a stagnation point it may be forced to one side of the stagnation line or the other, depending on its initial position. Results are presented for both of these cases.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-182297 , E-4834 , NAS 1.26:182297 , AIAA PAPER 89-1690 , Thermophysics Conference; Jun 12, 1989 - Jun 14, 1989; Buffalo, NY; United States
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  • 91
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    Domain decomposition algorithms and computation fluid dynamics (1988)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: In the past several years, domain decomposition was a very popular topic, partly motivated by the potential of parallelization. While a large body of theory and algorithms were developed for model elliptic problems, they are only recently starting to be tested on realistic applications. The application of some of these methods to two model problems in computational fluid dynamics are investigated. Some examples are two dimensional convection-diffusion problems and the incompressible driven cavity flow problem. The construction and analysis of efficient preconditioners for the interface operator to be used in the iterative solution of the interface solution is described. For the convection-diffusion problems, the effect of the convection term and its discretization on the performance of some of the preconditioners is discussed. For the driven cavity problem, the effectiveness of a class of boundary probe preconditioners is discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-185405 , NAS 1.26:185405 , RIACS-TR-88.21 , International Conference on Parallel and Vector Processing; Jun 01, 1988; Tromso; Norway
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  • 92
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    Direct numerical simulation of compressible free shear flows (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Direct numerical simulations of compressible free shear layers in open domains are conducted. Compact finite-difference schemes of spectral-like accuracy are used for the simulations. Both temporally-growing and spatially-growing mixing layers are studied. The effect of intrinsic compressibility on the evolution of vortices is studied. The use of convective Mach number is validated. Details of vortex roll up and pairing are studied. Acoustic radiation from vortex roll up, pairing and shape oscillations is studied and quantified.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 89-0374 , AIAA meeting; Jan 01, 1989; Reno, NV; United States|Annual Research Briefs, 1988; p 79-98
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  • 93
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    Performance of all-metal demountable cryogenic seals at superfluid helium temperatures (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Two all-metal demountable cryogenic seals with an outside diameter of 36.6 mm, inside diameter of 27.2 mm, and thickness of 0.51 mm were leak-tested at room temperature (300 K), liquid nitrogen temperature (21 cycles at 77 K), liquid helium temperature (9 cycles at 4.2 K), and susperfluid helium temperature (4 cycles at 1.6 K). Each seal was mounted and demounted for 13 cycles. Thickness measurements at 90 deg intervals along the circumference showed a maximum seal compression of 0.038 mm. Leak-rate measurements at all temperatures showed no detectable leak above the helium background level, typically 0.1 x 10(-9) std-cc/sec, during testing.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102190 , A-89101 , NAS 1.15:102190 , AIAA Thermophysics Conference; Jun 12, 1989 - Jun 15, 1989; Buffalo, NY; United States
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  • 94
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    A generalized one-dimensional computer code for turbomachinery cooling passage flow calculations (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A generalized one-dimensional computer code for analyzing the flow and heat transfer in the turbomachinery cooling passages was developed. This code is capable of handling rotating cooling passages with turbulators, 180 degree turns, pin fins, finned passages, by-pass flows, tip cap impingement flows, and flow branching. The code is an extension of a one-dimensional code developed by P. Meitner. In the subject code, correlations for both heat transfer coefficient and pressure loss computations were developed to model each of the above mentioned type of coolant passages. The code has the capability of independently computing the friction factor and heat transfer coefficient on each side of a rectangular passage. Either the mass flow at the inlet to the channel or the exit plane pressure can be specified. For a specified inlet total temperature, inlet total pressure, and exit static pressure, the code computers the flow rates through the main branch and the subbranches, flow through tip cap for impingement cooling, in addition to computing the coolant pressure, temperature, and heat transfer coefficient distribution in each coolant flow branch. Predictions from the subject code for both nonrotating and rotating passages agree well with experimental data. The code was used to analyze the cooling passage of a research cooled radial rotor.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-102079 , E-4839 , NAS 1.15:102079 , AVSCOM-TR-89-C-013 , AD-A242628 , Joint Propulsion Conference; Jul 10, 1989 - Jul 12, 1989; Monterey, CA; United States
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    Flight survey of the 757 wing noise field and its effects on laminar boundary layer transition. Volume 2: Data compilation (1987)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A flight test program was performed using the Boeing 757 flight research airplane to investigate the effect of noise from wing mounted engines on laminar boundary layer transition. An NLF glove was installed on the right wing panel just outboard of the engine. The extent of laminar flow on the glove was measured as a function of engine power setting for a range of flight conditions. A combination of surface and probe microphones was distributed over the upper and lower wing surfaces to measure sound spectra. The flight test program was completed in June 1985 and the results of preliminary analysis indicate that a maximum of about 29 percent of chord laminar flow was obtained on the upper surface and about 28 percent on the lower surface (at a high sideslip condition). The engine speed was varied from about 2600 (idle) to about 4500 (maximum continuous power) r/min. This produced changes in sound pressure level up to 20 dB on the lower surface. On the upper surface, the noise levels were independent of engine power but sensitive to airplane Mach number. No effect of engine power setting on upper surface transition location was observed, and only a small forward movement of the transition location on the lower surface was observed at the high power settings. Volume 1 of this report contains the program description and data analysis. Volume 2 is a compilation of all of the flight test data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178217 , NAS 1.26:178217 , D6-53196-2-VOL-2
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    A computationally efficient modelling of laminar separation bubbles (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The goal is to accurately predict the characteristics of the laminar separation bubble and its effects on airfoil performance. Toward this end, a computational model of the separation bubble was developed and incorporated into the Eppler and Somers airfoil design and analysis program. Thus far, the focus of the research was limited to the development of a model which can accurately predict situations in which the interaction between the bubble and the inviscid velocity distribution is weak, the so-called short bubble. A summary of the research performed in the past nine months is presented. The bubble model in its present form is then described. Lastly, the performance of this model in predicting bubble characteristics is shown for a few cases.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-184789 , NAS 1.26:184789
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  • 97
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    Modeling of transient heat pipe operation (1989)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Mathematical models and an associated computer program for heat pipe startup from the frozen state have been developed. Finite element formulations of the governing equations are written for each heat pipe region for each operating condition during startup from the frozen state. The various models were checked against analytical and experimental data available in the literature for three specific types of operation. Computations using the methods developed were made for a space shuttle reentry mission where a heat pipe cooled leading edge was used on the wing.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-184688 , NAS 1.26:184688
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  • 98
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    The influence of free-stream turbulence on turbulent boundary layers with mild adverse pressure gradients (1988)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The influence of near isotropic free-stream turbulence on the shape factors and skin friction coefficients of turbulent bounday layers is presented for the cases of zero and mild adverse pressure gradients. With free-stream turbulence, improved fluid mixing occurs in boundary layers with adverse pressure gradients relative to the zero pressure gradient condition, with the same free-stream turbulence intensity and length scale. Stronger boundary layers with lower shape factors occur as a result of a lower ratio of the integral scale of turbulence to the boundary layer thickness, and to vortex stretching of the turbulent eddies in the free stream, both of which act to improve the transmission of momentum from the free stream to the boundary layers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-184677 , NAS 1.26:184677
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  • 99
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    Structure of wind-shear turbulence (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The statistical characteristics of wind shear turbulence are modelled. Isotropic turbulence serves as the basis of comparison for the anisotropic turbulence which exists in wind shear. The question of turbulence scales in wind shear is addressed from the perspective of power spectral density.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-4213 , NAS 1.26:4213 , AIAA PAPER 88-0581 , Aerospace Sciences Meeting; Jan 01, 1988; Reno, NV; United States
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  • 100
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    Experimental determination of stator endwall heat transfer (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-101419 , E-4517 , NAS 1.15:101419 , International Gas Turbine and Aeroengine Congress and Exposition; Jun 04, 1989 - Jun 08, 1989; Toronto, Ontario; Canada
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