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  • FLUID MECHANICS AND HEAT TRANSFER
  • 1985-1989  (391)
  • 1950-1954
  • 1925-1929
  • 1985  (391)
  • 1
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    Simulation as an aid to phenomenological modeling (1985)
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    Publication Date: 2011-08-19
    Description: Certain difficulties arise in connection with the development of models for the prediction of turbulent flow characteristics. The present paper is mainly concerned with an approach which provides an aid in such development work by making it possible to test Reynolds average turbulence models. This approach is based on full and large eddy simulations of turbulent flows. Attention is given to details regarding Reynolds average turbulence models, mixing length models, two equation (k-epsilon) models, Reynolds stress models, and passive scalars. It is shown that a great deal about modeling can be learned from simulations of turbulent flows. There is reason to believe that these results will lead to improvements in the quality of predictions of turbulent flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 2
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    On a class of TVD schemes for gas dynamic calculations (1985)
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    Publication Date: 2011-08-19
    Description: The purpose of this paper is to review a class of explicit and implicit second-order accurate Total Variation Diminishing (TVD) schemes and to show by numerical experiments, the performance of these schemes to the Euler equations of gas dynamics. The method of constructing these second-order accurate TVD schemes is sometimes known as the modified flux approach.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 3
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    A Lagrangian method for the shallow water equations based on a Voronoi mesh - Flows on a rotating sphere (1985)
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    Publication Date: 2011-08-19
    Description: A Lagrangian scheme using the Voronoi mesh is applied to study shallow water flow on a sphere. Discrete approximations to the shallow water equations are obtained for the surfaces of a nonrotating and a rotating sphere, and discrete differential operators are defined for the gradient and the divergence on the sphere. Dissipation is put into the model, when needed, by merging fluid points when they get too close to each other. The full numerical scheme is described and results of numerical computations on various test cases are given, including zonal flow and the Riemann problem.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 4
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    Simultaneous measurements of temperature, density, and pressure in a supersonic turbulent flow using laser-induced fluorescence (1985)
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    Publication Date: 2011-08-19
    Description: A pulsed laser-induced fluorescence technique is described that provides simultaneous measurements of temperature, density, and pressure in low-temperature, turbulent flows. The measurements are made with spatial and temporal resolution comparable to that obtained with modern laser anemometer techniques used for turbulent boundary layer research. The capabilities of the method are briefly described and its demonstration in a simple two-dimensional turbulent boundary layer at Mach 2 is reported. The results are compared with conventional hot-wire anemometer data obtained in the same flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 5
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    Evolution of a vortical structure associated with the bursting event in a channel flow (1985)
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    Publication Date: 2011-08-19
    Description: The temporal evolution of a horseshoe vortex structure in a channel is investigated by a numerical simulation. A spectral numerical method is employed to integrate the time-dependent, three-dimensional Navier-Stokes equations. The initial vortical structure is obtained by applying a conditional sampling technique to a data base generated from a direct simulation of a turbulent channel flow. The evolution of this vortical structure under the influence of the self-induced motion and the mean shear is presented. It is shown that the initial sheet-like vortical structure rolls up into a vortex tube as it is convected downstream. Turbulence structures associated with the vortex stretching are investigated. Production of vorticity stretching is high inside the vortex legs, although it is also substantial in the tip region and above the legs. High Reynolds shear stress is produced near the tip of the vortex.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 6
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    Simulation of turbulent mixing layers (1985)
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    Publication Date: 2011-08-19
    Description: A hybrid numerical scheme, combined with a scalar convection scheme, is used to compute turbulent mixing layers. The hybrid scheme is used to solve the vorticity equation by dividing the domain into two regions, applying a Lagrangian method in one region and an Eulerian method in the other. The scalar convection scheme is used to track an interface which separates a dyed fluid from a dye-free fluid, thereby distinguishing the fluid that starts on the high speed side from the fluid that starts on the low speed side. A two-dimensional mixing layer has been simulated using this new method; the roll up of a vortex sheet into structures that interact and pair is observed. The growth of the momentum thickness and the development of the mean turbulence statistics are found to be consistent with experimental observations. Forcing of the layer at moderate and low frequencies shows a dramatic effect on the growth of the momentum thickness and the entrainment ratio. Low frequency forcing enhances the growth of the layer; moderate frequency forcing inhibits the growth.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 7
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    The effects of compliant walls on transition and turbulence (1985)
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    Publication Date: 2011-08-19
    Description: Two theoretical approaches to the phenomenon of drag reduction by a compliant wall are proposed. One is to study the limit cycle oscillations of the Navier-Stokes equations for a boundary layer flow over a compliant wall or a Poiseuille flow in a channel with a compliant wall. The other is a complementary study of a simpler, sequential model, which partially decouples the fluid and wall motions. In this approach, a 'Total Model' is constructed from suitable component models. While the first study is more rigorously based, it will be initially limited, by computational constraints, to relatively low Reynolds numbers. The second, more approximate approach, will allow consideration of a fully developed turbulent flow. The Total Model will predict the compliant wall motion accurately, but will not per se be sufficient to predict the skin friction drag. However, once the wall motion is known, the skin friction drag and the pressure drag can be computed separately, using one of the existing models.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 8
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    Analysis of buoyancy effect on fully developed laminar heat transfer in a rotating tube (1985)
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    Publication Date: 2011-08-19
    Description: Laminar heat transfer is analyzed in a tube rotating about an axis perpendicular to the tube axis. The solution applies for flow that is either radially outward from the axis of rotation, or radially inward toward the axis of rotation. The conditions are fully developed, and there is uniform heat addition at the tube wall. The analysis is performed by expanding velocities and temperature in power series using the Taylor number as a perturbation parameter. Coriolis and buoyancy forces caused by tube rotation are included, and the solution is calculated through second-order terms. The secondary flow induced by the Coriolis terms always tends to increase the heat transfer coefficient; this effect can dominate for small wall heating. For radial inflow, buoyancy also tends to improve heat transfer. For radial outflow, however, buoyancy tends to reduce heat transfer; for large wall heating this effect can dominate, and there is a net reduction in heat transfer coefficient.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 107; 338-344
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  • 9
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    Shape instability in thin viscous films and jets (1985)
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    Publication Date: 2011-08-19
    Description: The theory of viscous liquid films and thin jets as two- and one-dimensional continua is examined. Theoretical results are presented concerning a special type of instability which leads to the loss of smoothness of the shape (wrinkling) and associated with the failure of hyperbolicity of the governing equations. The conditions for different types of such an instability are formulated in the closed analytical form.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Acta Mechanica (ISSN 0001-5970); 55; 33-50
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  • 10
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    Features of a reattaching turbulent shear layer in divergent channel flow (1985)
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    Publication Date: 2011-08-19
    Description: Experimental data have been obtained in an incompressible turbulent flow over a rearward-facing step in a diverging channel flow. Mean velocities, Reynolds stresses, and triple products that were measured by a laser Doppler velocimeter are presented for two cases of tunnel wall divergence. Eddy viscosities, production, convection, turbulent diffusion, and dissipation (balance of kinetic energy equation) terms are extracted from the data. These data are compared with various eddy-viscosity turbulence models. Numerical calculations incorporating the k-epsilon and algebraic-stress turbulence models are compared with the data. When determining quantities of engineering interest, the modified algebraic-stress model (ASM) is a significant improvement over the unmodified ASM and the unmodified k-epsilon model; however, like the others, it dramatically overpredicts the experimentally determined dissipation rate.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 163-171
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  • 11
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    Developments in the simulation of compressible inviscid and viscous flow on supercomputers (1985)
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    Publication Date: 2011-08-19
    Description: In anticipation of future supercomputers, finite difference codes are rapidly being extended to simulate three-dimensional compressible flow about complex configurations. Some of these developments are reviewed. The importance of computational flow visualization and diagnostic methods to three-dimensional flow simulation is also briefly discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 12
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    Effects of wall curvature on turbulence statistics (1985)
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    Publication Date: 2011-08-19
    Description: A three-dimensional, time-dependent, direct numerical simulation of low-Reynolds number turbulent flow in a mildly curved channel was performed, and the results examined to determine the mechanism by which curvature affects wall-bounded turbulent shear flows. A spectral numerical method with about one-million modes was employed, and no explicit subgrid scale model was used. The effects of curvature on this flow were determined by comparing the concave and convex sides of the channel. The observed effects are consistent with experimental observations for mild curvature. The most significant difference in the turbulence statistics between the concave and convex sides is in the Reynolds shear stress. This is accompanied by significant differences in the terms of the Reynolds shear stress balance equations. In addition, it was found that stationary Taylor-Goertler vortices were present and that they had a significant effect on the flow by contributing to the mean Reynolds shear stress, and by enhancing the difference between the wall shear stresses.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 13
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    Structure of turbulence in the presence of uniform shear (1985)
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    Publication Date: 2011-08-19
    Description: The structure of the vorticity field in homogeneous turbulent shear flow is analyzed using a database generated by direct numerical solution of the unsteady Navier-Stokes equations with up to 128x128x128 grid points. For two Reynolds numbers, the probability distribution of the inclination angle of the vorticity vectors, two-point correlations of the velocity and vorticity fields, and the instantaneous vorticity vectors and vortex lines in three-dimensional space were examined. It is shown that homogeneous turbulent shear flow contains a large number of horseshoe vortices. These vortices are most often found in planes inclined at 45 deg to the flow direction and are formed from the roll-up of sheets of transverse vorticity. These findings and similar results obtained in turbulent channel flow, lead to the conclusion that hairpin vortices are the characteristic vortical structures in all turbulent shear flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 14
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    Direct numerical simulation of equilibrium turbulent boundary layers (1985)
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    Publication Date: 2011-08-19
    Description: This paper describes the simulation of turbulent boundary layers by direct numerical solution of the three-dimensional, time-dependent Navier-Stokes equations, using a spectral method. The flow is incompressible, with Re sub delta = 1000. The equations are written in the self-similar coordinate system and periodic streamwise and spanwise boundary conditions are imposed. A family of nine 'equilibrium' boundary layers, from the strongly accelerated 'sink' flow to Stratford's separating boundary layer is treated. Good general agreement with experiments is observed. The effects of pressure gradients on the structures and statistics, both in the wall and wake regions are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 15
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    Enthalpy damping for the steady Euler equations (1985)
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    Publication Date: 2011-08-19
    Description: For inviscid steady flow problems where the enthalpy is constant at steady state, it was previously proposed to use the difference between the local enthalpy and the steady state enthalpy as a driving term to accelerate convergence of iterative schemes. This idea is analyzed, both on the level of the partial differential equation and on the level of a particular finite difference scheme. It is shown that for the two-dimensional unsteady Euler equations, a hyperbolic system with eigenvalues on the imaginary axis, there is no enthalpy damping strategy which moves all the eigenvalues into the open left half plane. For the numerical scheme, however, the analysis shows and examples verify that enthalpy damping is potentially effective in accelerating convergence to steady state.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Applied Numerical Mathematics (ISSN 0168-9274); 1; 417-432
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  • 16
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    Double-diffusive convection with sidewalls (1985)
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    Publication Date: 2011-08-19
    Description: Stommel et al. (1956) have first described an instability, known as thermosolutal convection, thermohaline convection, or double-diffusive convection. This instability may occur in the case of a fluid in a gravitational field with two diffusing components present. The present study is concerned with the effect of sidewalls on flow in the fingering regime in the absence of applied horizontal gradients. The work was motivated by numerical results obtained on the basis of a simulation of thermosolutal convection occurring during the unidirectional solidification of a binary alloy. In this case, the unperturbed solute field in the liquid ahead of the solidifying planar interface has an exponential vertical profile because of the rejection or preferential incorporation of solute by the solid phase.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 28; 2716-272
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  • 17
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    Internal combustion engine combustion chamber process studies at NASA Lewis Research Center (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 1; 351-353
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  • 18
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    Liquid management in low gravity using baffled rotating containers (1985)
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    Publication Date: 2011-08-19
    Description: Possible static configurations of liquids in rotating cylindrical containers with baffles evenly spaced in the axial direction are found. The force balance is among surface tension, centrifugal force and gravity. Two instabilities are found in this parameter space: type 1 is the inability of the liquid to form an interface attached to the baffles; type 2 is the inability for multi-baffled configurations to sustain interfaces between each pair of baffles. The type 1 analysis is confirmed through laboratory based equipment. Applications to orbiting containers are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 287
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  • 19
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    Navier-Stokes calculations for unsteady three-dimensional vortical flows in unbounded domains (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 868-874
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  • 20
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    A finite difference method for solving unsteady viscous flow problems (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 659-668
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  • 21
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    Computing three-dimensional incompressible flows with vortex elements (1985)
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    Publication Date: 2011-08-19
    Description: The techniques, capabilities and applicability of numerical models of three-dimensional, unsteady vortical flows with high Re are assessed. Vorticity is calculated only in appropriate regions and the velocity field is derived from the boundary conditions. Vorticity is assumed to take the shape of tubes with uniform core structures in the case of turbulence. The efforts being made to simplify equations for dense collections of vortex filaments in order to make them tractable to computer simulations are described. The effectiveness of vorticity arrow representations for accurately describing vorticity fields near surfaces is discussed, along with Lagrangian vortex elements, which may be of use in modelling the rotational part of flows around bluff bodies, nonuniform density flows and chemically reacting flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 22
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    Aerodynamics of sports balls (1985)
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    Publication Date: 2011-08-19
    Description: Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 23
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    Oscillations of a compound drop system undergoing rotation (1985)
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    Publication Date: 2011-08-19
    Description: A compound liquid-drop system is comprised of three immiscible concentric fluids: a core fluid of density p(i) surrounded by a shell of density p(s) which is embedded in a medium of density p(o). In this analysis, the fluids are incompressible and inviscid. The effect of rotation upon the modes of oscillation of a compound drop is investigated. Rotation rate is considered as a small perturbation of the normal modes of the compound drop, thus introducing the effects of a Coriolis force and a centrifugal distortion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 28; 1023-102
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  • 24
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    Aerodynamic effect of combustor inlet air pressure on fuel jet atomization (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 1; 137-142
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  • 25
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    Impact of computational fluid dynamics on development test facilities (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Aircraft (ISSN 0021-8669); 22; 182-187
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  • 26
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    The temperature distribution within a sphere placed in a directed uniform heat flux and allowed to radiatively cool (1985)
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    Publication Date: 2011-08-19
    Description: The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 107; 28-32
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  • 27
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    Vortex motion in wall-bounded viscous flow (1985)
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    Publication Date: 2011-08-19
    Description: A factor of general interest in a broad class of wall-bounded flows is the dynamic evolution of vortical structures through the flow. The structures are three-dimensional, and an overall mathematical description of such entities has not yet been formulated. One of the objectives of the present investigation is concerned with the establishment of a framework, based on first principles, which may form a basis for more detailed analytical studies. Another aim is related to the establishment of boundary and initial conditions in numerical experiments. The mathematical framework employed involves the method of matched asymptotic expansions, and an inner solution field is constructed which consists of a two-dimensional vortical structure. The outer solution field is taken to be an otherwise undisturbed laminar two-dimensional parallel or self-similar viscous flowfield.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proceedings, Series A - Mathematical and Physical Sciences (ISSN 0080-4630); 397; 1813,
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  • 28
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    A perspective of theoretical and applied computational fluid dynamics (1985)
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 328-341
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  • 29
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    Turbulence structures associated with the bursting event (1985)
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    Publication Date: 2011-08-19
    Description: Turbulence structures in a wall bounded shear layer during the bursting event detected by a conditional sampling technique are investigated using data obtained from large eddy simulation of turbulent channel flow. Streamlines are constructed from the ensemble-averaged velocity field to illustrate the flow patterns associated with the bursting event. The splatting motions during the sweep event and the existence of a pair of counterrotating streamwise vortices during the ejection process are exhibited.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 28; 52-58
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  • 30
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    Analytical model for large-scale turbulence (1985)
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    Publication Date: 2011-08-19
    Description: The paper presents an analytical model for large-scale turbulence, based on a new closure which depends on the growth rate of the instability-generating turbulence. For convection in stars the results of the mixing-length theory are recovered, and for laboratory convection the N = R to the 1/3 power law is recovered. The present model can readily be extended to include magnetic fields and rotation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review Letters (ISSN 0031-9007); 54; 430-433
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  • 31
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    Flat-plate transition (1985)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A new research effort was undertaken to build a boundary-layer transition tunnel. This facility only recently became operational. The data obtained so far are merely qualitative. The main goal is to predict heat transfer given any combination of factors such as pressure gradient, turbulence level, Reynolds number, or intermittency factor. The boundary-layer transition tunnel is a closed-loop tunnel that controls the turbulence level, velocity and temperature of the air within it. Problems associated with the operation of this tunnel are examined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Transition in Turbines; p 61-68
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  • 32
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    Combustor turbulence (1985)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The turbulence entering the turbine is produced in the combustor. High turbulence levels from the combustor can alter the location of the transition point on the turbine vane. The dynamics of turbulence and the progress being made in computing the flow are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Transition in Turbines; p 5-16
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  • 33
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    Transition in a disturbed environment (1985)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The title of this presentation is the title of our research grant. While transition study is the objective of the work, the results to date are principally on the properties of turbulent boundary layers at low Reynolds numbers are discussed. Testing was done in a small return wind tunnel. Mean boundary layer development is given. The skin friction behavior of the turbulent points are considered. No standard laminar flow was observed. Furthermore, the turbulent mean flow data seem reasonable for the elevated disturbance levels of the tests in the sense that there is no discernible wake component to any of the profiles and that the variation of skin friction with R sub theta is consistent with zero wake strength. The no-grid data are in all likelihood transitional.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Transition in Turbines; p 35-48
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  • 34
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    Fluid and gas dynamics (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A clearer understanding of the interactions of the hot gas flow with the structure in the duct system, the flow passages of the rotating machinery, and the thrust chamber nozzle is sought for the purpose of finding ways and means to increase the life and performance of the systems. The objective of the transient nozzle test is to understand the shock-boundary layer interactions during transient flow and the resulting large side forces acting on the nozzle skirt. The Fluctuating Pressures in Ducts study deals mainly with the fluid-structural interactions of the lox post tube banks in the injector. The Ablative Nozzle Insert Study (H4) has as its goal the performance improvement of the space shuttle main engine.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Advan. High Pressure O2(H2 Technol.; p 508-510
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    Analytical study of flow phenomena in SSME turnaround duct geometries (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The SSME fuel turbopump hot gas manifold was identified as a source of loss and flow distortion which significantly affects the performance and durability of both the drive turbine and the LOX injector area of the main combustion chamber. Two current SSME geometries were studied, the full power level (FPL) and the first manned orbital flight (FMOF) configuration. The effects of turnaround duct geometry on flow losses and distortions, by varying wall curvature and flow area variation in the 180 deg turnaround region were examined. The effects of the duct inlet flow phenomena such as the radial distortion of the inlet flow and inlet swirl level on turnaround duct performance were also investigated. It is shown that of the two current geometries, the FMOF configuration had lower pressure losses and generated less flow distortion, but had a small flow separation bubble at the 180 deg turnaround exit. It is found that by optimizing wall curvature and flow diffusion in the turnaround, improved duct performance can be achieved.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center Advan. High Pressure O2(H2 Technol.; p 579-598
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  • 36
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    Theoretical interpretation of thermal arrest data from differential thermal analysis measurements (1985)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: A theory was developed to interpret the thermal arrest data of HgCdTe system from differential thermal analysis measurements. A nonlinear regression program is used to model fit the data. The purpose is to obtain a set of parameters which will give the information about average radiation coefficient, latent heat of fussion, and specific heat of the HgCdTe system at various compositions. The liquidus and solidus at various compositions are also obtained. The heat radiation from the furnace, heat radiation from the system, heat capacity from both the system and the quartz tube and the heat of fusion of the system are considered, however, it neglects heat transfer through conduction and convection.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: 1984 NASA/ASEE Summer Faculty Fellowship Program (NASA-CR; 13p
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  • 37
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    Hydrodynamic stability problem formulated by numerical solutions of the Navier-Stokes equations (1985)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: The problem of hydrodynamic stability and the transition from laminar to turbulent flows are reformulated by seeking numerical solutions of the full, unapproximated Navier-Stokes equations. This method differs significantly from the well known Orr-Sommerfeld equation approach. The oncoming laminar flow is disturbed by forced, time dependent perturbations. The magnitudes of these perturbations are arbitrary. Then, the ensuing spatial and temporal development of the imposed perturbations on the basic flow is calculated by direct numerical solutions of the time dependent Navier-Stokes equations. One of the main advantages of this method is its ability to simulate nonlinear processes. As a specific application of this technique to SSME (Space Shuttle Main Engine) flow configurations, computer programs have been written for the two dimensional flow over a backward facing step. This numerical code will be tested for operational use as part of a continued research collaboration effort with the NASA/MSFC counterparts.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: 1984 NASA/ASEE Summer Faculty Fellowship Program (NASA-CR; 10p
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  • 38
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    A study of the compatibility of an existing CFD package with a broader class of material constitutions (1985)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: The flexibility of the PHOENICS computational fluid dynamics package was assessed along two general avenues; parallel modeling and analog modeling. In parallel modeling the dependent and independent variables retain their identity within some scaling factors, even though the boundary conditions and especially the constitutive relations do not correspond to any realistic fluid dynamic situation. PHOENICS was used to generate a CFD model that should exhibit the physical anomalies of a granular medium and permit reasonable similarity with boundary conditions typical to membrane or porous piston loading. A considerable portion of the study was spent prying into the existing code with a prejudice toward rate type and disarming any inherent fluid behavior. The final stages of the study were directed at the more specific problem of multiaxis loading of cylindrical geometry with a concern for the appearance of bulging, cross slab shear failure modes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: 1984 NASA/ASEE Summer Faculty Fellowship Program (NASA-C; 21 p
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  • 39
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    A review and analysis of boundary layer transition data for turbine application (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information. The data were analyzed by using a version of the STAN5 two-dimensional boundary layer code. The transition starting and ending points were determined by adjusting parameters in STAN5 until the calculations matched the data. The results are presented as a table of the deduced transition location and length as functions of the test parameters. The data sets reviewed cover a wide range of flow conditions, from low-speed, flat-plate tests to full-scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free-stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Transition in Turbines; p 81-93
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  • 40
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    Preliminary results of a study of the relationship between free-stream turbulence and stagnation region heat transfer (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Preliminary results of a study to investigate the relationship between free stream turbulence and heat transfer augmentation in the stagnation region is presented. The effects of free stream turbulence and surface roughness on spanwise averaged heat transfer were investigated. Turbulence was measured upstream of a cylinder placed in the wake of an array of parallel wires that were perpendicular to the cylinder axis. Finally, flow visualization and thermal visualization techniques were combined to show the relationship between vortices in the stagnation region and spanwise variations in heat transfer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Transition in Turbines; p 17-34
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  • 41
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    Bypass transition to turbulence and research Desiderata (1985)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Bypass transitions are seldom mentioned in texts or meetings on instability and transition to wall turbulence. The nature of a number of bypass transitions is illustrated by example. Until this characteristics is truly understood predicting transition on the basis of theory or statistically inadequate correlations (as they all are) entails risks that should be considered in justifying any design involving transition. A historical overview of bypass transition identified on blunt bodies is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Transition in Turbines; p 161-204
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  • 42
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    Unsteady Heat Transfer Due to Time-dependent Free Stream Velocity (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-30
    Description: The present work was undertaken in order to study the unsteady combined convection from a horizontal circular cylinder to a transverse flow. A coordinate perturbation method is used to transform the governing set of partial differential equations into a system of ordinary differential equations. The free stream time-dependent velocity was assumed to be sinusoidal and the boundary layer response due to both low as well as high frequencies of oscillation will be studied. Currently numerical solutions are being obtained for the distribution of the unsteady Nusselt number and the friction factor.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 39-40
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  • 43
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    Calculation of Viscous Compressible Flows in Small Gas Turbines (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-30
    Description: The NASA Lewis Research Center is conducting a program to develop improved technology for the space shuttle main engine (SSmE). This program requires not only a component test program, but also the development of accurate and reliable analyses to support the program. Thus a computer analysis for the prediction of the flow of hot gases, composed of a variety of exhaust products, through rocket and gas turbine components would support this program and also would be suitable for a wide variety of other applications.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 53-57
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  • 44
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    Flow-induced Vibration of SSME Main Injector Liquid-oxygen Posts (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-30
    Description: The liquid-oxygen (LOX) posts are exposed to hot hydrogen flowing over the tubes on its way to the combustion chamber. Fatigue cracking of some LOX posts was observed after test firing of the SSMEs. A current design modification consists of attaching impingement shields to the LOX posts in the outer row. The modification improved the vibration/fatigue problem of the LOX posts, but resulted in an increased pressure drop that ultimately shortened the life expectancy of other components. A fundamental study of vibration of the LOX posts was initiated to understand the flow-induced vibration problem and to develop techniques to avoid detrimental vibrational effects with the overall objective of improving engine life. This effort, including an assessment of the problem, scoping calculation and experiment, and a work plan for an integrated theoretical/experimental study of the problem is summarized.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 59-61
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  • 45
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    New Facility to Study Unsteady Wake Effects on Turbine Airfoil Heat Transfer (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-27
    Description: A significant portion of the SSME aerothermal loads program is directed at the heat transfer effects of the unsteady flows, particularly wakes, that occur naturally in turbomachinery. Although these phenomena occur in all turbomachines, we feel they will be more severe in the SSME turbines because of the high heat transfer associated with the very high Reynolds numbers over the SSME airfoils.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 41-47
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  • 46
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    Experimental Measurements and Analysis of Heat Transfer and Gas Dynamics in a Rotating Turbine Stage (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-30
    Description: The life-cycle fatigue of a particular component of a high-pressure turbine stage is influenced by the local heat flux and the resulting metal temperature excursions experienced by this component during normal operation. Flow through a turbine stage is seldom uniform and is often influenced by non-uniform incoming gas streams that can result in locally high heat fluxes. In the case of the rotor blades passing through the nozzle guide vane wakes and passages, these local heat rates translate into local temperature fluctuations that will likely affect the fatigue life of the blade. In order to better understand the influence of the heat load on the component life, one would like to have both the local steady-state heat flux and the high-frequency component of the heat flux.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 49-52
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  • 47
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    Unsteady Flow in Multistage Turbines (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-30
    Description: The development of an efficient model for the response of a multistage turbine to either a total pressure or total temperature distortion is discussed. Each turbine blade row is modeled as an actuator disk and is often used to describe the flow through turbine and compressor blade rows. The flow approaching the blade row is assumed to be subsonic and inviscid. The distortion occurs at upstream infinity and is in the form of total pressure or total temperature. A solution was found to unsteady Euler equations by using a finite volume method. With prescribed inlet and boundary conditions flow variables such as density, pressure, and velocities can be calculated at cell centers in the entire flow region. The inlet and exit of the blade row coincide with lines of constant.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 37-38
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    Simulation of Multistage Turbine Flows (1985)
    In:  CASI
    Details
    Publication Date: 2014-08-27
    Description: The numerical simulation of turbine flows serves to enhance the understanding of the flow phenomena within multistage turbomachinery components. The direct benefit of this activity is improved modeling capability, which can be used to improve component efficiency and durability. A hierarchy of equations was formulated to assess the difficulty in analyzing the flow field within multistage turbomachinery components. The Navier-Stokes equations provides the most complete description. The simplest description is given by a set of equations that govern the quasi-one-dimensional flow. The number of unknowns to be solved for increases monotonically above the number of equations. The development of the additional set of equations needed to mathematically close the system of equations forms the closure problem associated with that level of description. For the Navier-Stokes equation there is no closure problem. For the quasi-one-dimensional equation set random flow fluctuations, unsteady fluctuations, nonaxisymmetric flow variations, and hub-to-shroud variations on the quasi-one-dimensional flow must be accounted for.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Struct. Integrity and Durability of Reusable Space Propulsion Systems; p 27-36
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  • 49
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    On the mixing of a row of jets with a confined crossflow (1985)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Mean temperature profiles calculated with an interactive microcomputer code which evaluates dilution-zone design alternatives are presented to show the effects of flow and geometric variables on the mixing of a single row of jets injected through sharp-edged orifices into a uniform flow of a different temperature in a constant area duct. In addition, this program is used to calculate profiles for opposed rows of jets with their centerlines in-line, by assuming that the confining effect of an opposite wall is equivalent to that of a plane of symmetry between opposed jets.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbine Engine Hot Section Technology, 1985; p 133-138
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  • 50
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    Measurements of rotating bubble shapes in low-gravity environment (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of rotating equilibrium bubble shapes in the low-gravity environment of a free-falling aircraft are presented. Emphasis is placed on bubbles which intersect the container boundaries. These data are compared with theoretical profiles derived from Laplace's formula and are in good agreement with the measurements. The interface shape depends on the contact angle, the radius of intersection with the container, and the parameter F, which is a measure of the relative importance of centrifugal force to surface tension. For isolated bubbles F has a maximum value of 1/2. A further increase in F causes the bubble to break contact with the axis of rotation. For large values of F the bubble becomes more cylindrical and the capillary rise occurs over a thinner layer in order that the small radius of curvature can generate a sufficient pressure drop to account for the increased hydrostatic contribution.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 161; 269-279
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    Measurements of fluctuating temperatures in a supersonic turbulent flow using laser-induced fluorescence (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 1932-193
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    Experimental study of the oscillations of a rotating drop (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two- and three-lobed oscillations of a rotating liquid drop immersed in an immiscible fluid of comparable density and the same angular velocity were studied experimentally. Using acoustically suspended drops, it has been found that the relative change in the resonance frequencies of the axisymmetric drop-shape oscillations Delta omega-l/omega-l(0) is proportional to the square of the normalized angular speed (Omega/omega-l/0)-squared when omega-l greater than 2 Omega. This is in agreement with a recent analytical study of the same problem. Some preliminary results regarding the effect of rotation on the free-decay rate of the two-lobed oscillations are also presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 158; 317-327
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    Flow formed by spanwise gaps between roughness elements (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of the three mean velocity components and the three Reynolds shear stresses were made in the region downstream of gaps between wall-mounted roughness elements of square cross section and high aspect ratio in a thick turbulent boundary layer. The effect of small and large gaps was studied in a wind tunnel at a Reynolds number of 3600, based on obstacle height and free-stream velocity. The small gap produces retardation of the gap flow as with a two-dimensional roughness element, but a definite interaction between gap and wake flows is observed. The interaction is more intense for the large gap than for the small. Both gaps generate a secondary crossflow which moves fluid away from the centerline in the wall region and toward the centerline in the outer (y greater than 1.5H) region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME, Transactions, Journal of Fluids Engineering (ISSN 0098-2202); 107; 385-391
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    A mathematically simple turbulence closure model for attached and separated turbulent boundary layers (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 1684-169
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    Rotary radiators for reduced space powerplant temperatures (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: If new radiator concepts can achieve radiator weights below 3 kg/sq m, nuclear space powerplants can operate at temperatures below 900 K and use stainless steel construction. Tube-and-fin or heat-pipe radiators weigh at least 5 kg/sq m because the tube walls must be thick enough to prevent or limit meteoroid punctures. However, radiators that require no meteoroid protection can be built using low-vapor-pressure liquids that can be exposed directly to space. One possible design for such a radiator is the 'rotary radiator' that uses centrifugal force to move the liquid across a thin radiating disk and uses surface tension to retain the liquid despite meteoroid punctures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Steady inviscid three-dimensional flows (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present analysis combines some of the theoretical concepts suggested by Hawthorne (1955) with a numerical integration procedure suggested by Martin (1978). The resulting algorithm is for inviscid subsonic flows. Thus, it is restricted to high Reynolds number flows. Chang and Adamczyk (1983) have provided a detailed derivation of the present algorithm along with a discussion of its stability bounds. The present paper represents a summary of this work. The integration of the continuity equation is considered along with an evaluation of the entropy, total temperature, and vorticity field. Attention is given to the shear-flow algorithm construction, and an application to a shear flow in a turning channel. A description of numerical results is also provided. The discussed algorithm represents a new procedure for solving inviscid subsonic three-dimensional rotational flows.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Covariances and spectra of the kinematics and dynamics of nonlinear waves (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Using the Stokes waves as a model of nonlinear waves and considering the linear component as a narrow-band Gaussian process, the covariances and spectra of velocity and acceleration components and pressure for points in the vicinity of still water level were derived taking into consideration the effects of free surface fluctuations. The results are compared with those obtained earlier using linear Gaussian waves.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 11
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    Thermal management of high power space based systems (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Conventional techniques of using a portion of the spacecraft skin for radiation of waste heat will be inadequate for high powered payloads (50 to 100 kWe) due to the lack of sufficient area. A Shuttle type system using a pumped single phase fluid loop could be scaled up to higher power but this type of system would require excessive pump power and weight. A pumped two-phase heat transfer loop has a much lower pumping requirement due to the higher latent heat of vaporization of the fluid in comparison to the sensible heat it can absorb through a temperature change. Concepts for an evaporator and a condenser for a pumped two-phase system are described. The condenser uses capillary grooves and a separate pumped condensate return line to achieve high heat transfer coefficients and stable operation due to the separation of the vapor and liquid flows. The cold plate evaporator uses wicks to contain the liquid and transport it to the heated surface. It can also function as a condenser for warming components. Control concepts for the cold plate are discussed. Concepts for deployment or erection of large space radiators are also considered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Scattering of acoustic waves into Tollmien-Schlichting waves by small streamwise variations in surface geometry (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: By using the triple-deck scaling of Stewartson (1969) and Messiter (1970) it is shown that small but relatively sudden surface geometry variations that produce only very weak static pressure variations can nevertheless produce strong, i.e. O(1), coupling between an externally imposed acoustic disturbance and a spatially growing Tollmien-Schlichting wave. The analysis provides a qualitative explanation of the Leehey and Shapiro (1979) boundary-layer receptivity measurements and is in good quantitative agreement with the Aizin and Poliakov (1979) experiment. It may also explain why small 'trip wires' can promote early transition.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 154; 509-529
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    The structure of the vorticity field in turbulent channel flow. I - Analysis of instantaneous fields and statistical correlations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An investigation into the existence of hairpin vortices in turbulent channel flow is conducted using a database generated by the large eddy simulation technique. It is shown that away from the wall the distribution of the inclination angle of vorticity vector attains its maximum at about 45 deg to the wall. Two point correlations of velocity and vorticity fluctuations strongly support a flow model consisting of vortical structures inclined at 45 deg to the wall. The instantaneous vorticity vectors plotted in planes inclined at 45 deg show that the flow contains an appreciable number of hairpins. Vortex lines are used to display the three dimensional structure of hairpins, which are shown to be generated from deformation of transverse vortex filaments.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 155; 441-464
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    Viscous damping of the oscillations of a rotating simple drop (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The viscous damping of the small-amplitude capillary oscillations of a rotating simple drop is calculated in the small viscosity limit. The calculation concerns the case of a liquid drop in a gaseous medium, which is relevant to the space processing of materials using acoustic levitation. The method used is that of Lamb in which the inviscid solutions of the problem are used as trial functions in the energy equation to find the damping coefficient.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 28; 3187
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    Application of TVD schemes for the Euler equations of gas dynamics (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: First-order, second-order, and implicit total variation diminishing (TVD) schemes are reviewed using the modified flux approach. Some transient and steady-state calculations are then carried out to illustrate the applicability of these schemes to the Euler equations. It is shown that the second-order explicit TVD schemes generate good shock resolution for both transient and steady-state one-dimensional and two-dimensional problems. Numerical experiments for a quasi-one-dimensional nozzle problem show that the second-order implicit TVD scheme produces a fairly rapid convergence rate and remains stable even when running with a Courant number of 10 to the 6th.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Turbulence measurements in shock-induced flows (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 1172-117
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    Higher order methods for convection-diffusion problems (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: This paper applies C1 cubic Hermite polynomials embedded in an orthogonal collocation scheme to the spatial discretization of the unsteady nonlinear Burgers equation as a model of the equations of fluid mechanics. The temporal discretization is carried out by means of either a noniterative finite difference or an iterative finite difference procedure. Results of this method are compared with those of a second-order finite difference scheme and a splined-cubic Taylor's series scheme. Stability limits are derived and the matrix structure of the several schemes are compared.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computers and Fluids (ISSN 0045-7930); 13; 2, 19
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    Analysis of three-dimensional solidification interface shape (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The determination of the shape of the solidification interface in a cooling melt by the thermal boundary conditions is investigated analytically, extending the analysis of Siegel (1982) and Siegel and Sosoka (1982) to the three-dimensional case. The solutions are generated by continuation into the solid region from conditions at the cooled wall, and some numerical results are presented in tables and graphs. These findings and the analytical approach employed are applicable to crystallization and metal-forming processes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer (ISSN 0017-9310); 28; 701-705
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    Nonreflecting boundary conditions for the complete unsteady transonic small-disturbance equation (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nonreflecting far-field boundary conditions that are consistent with the complete transonic small-disturbance (TSD) equations are derived. They are implemented in a new code for solving the complete TSD equation and are tested for a harmonically oscillating NACA 64A010 airfoil in transonic flow and for a flat-plate airfoil with a pulse in the angle of attack. Using the new boundary conditions on a relatively small grid, solutions for the airfoil that are obtained that agree with large-grid calculations, resulting in a 44 percent savings in computer time. Frequency responses for the flat plate show that most of the disturbances incident on the computational boundaries are absorbed by the boundary conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 315-317
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    Ablation of Galileo Probe heat-shield models in a ballistic range (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Several 1/24-scale models of the Galileo Probe made of carbon-phenolic materials were flown in a ballistic range to test their ablation characteristics. Mostly radiative or all-convective heating environments were produced by using argon or air as the test gas, respectively, to simulate the Jovian entry heating environments. The experimental results were compared with the theoretical predictions made using the computer codes of radiating shock layer environment (RASLE) and charring materials ablation (CMA). The experimental data obtained in argon agreed approximately with the theoretical predictions. The data for air agreed approximately with the theory when turbulence and surface roughness effects were accounted for. The data imply that the Galileo Probe heat shield was adequately designed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 23; 301-308
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    Turbulent Reynolds analogy factors for nonplanar surface microgeometries (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Direct measurements of turbulent Reynolds analogy factors are presented for 15 nonplanar surface microgeometries (including riblets, oscillating transverse curvature, wavy walls, and micro air bearings) for momentum thickness Reynolds numbers of 1638-2631. It is shown that certain types of nonplanar surface microgeometries will increase turbulent Reynolds analogy factors significantly above flat-plate levels. In several cases, the observed elevated heat-transfer efficiencies represent the combined effects of both heat-transfer increases and drag decreases. Generally, the results suggest that decreases of the order of 20 percent are possible in heat exchanger volume, cost, and weight for designs with extensive planar surfaces.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 581
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    Experimental aerodynamic heating to simulated Shuttle tiles (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 417-424
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    Control of solidification boundary in continuous casting by asymmetric cooling and mold offset (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A solution, developed to obtain solidification-interface shapes for complex situations in which both the ingot cooling and mold geometry are asymmetric, is analyzed. The effect of mold offsett and of unequal ingot side temperatures on the interface shapes is illustrated in graphs. The results of the analysis show how the solidification interface in continuous casting can be controlled by asymmetries in both mold geometry and cooling of the ingot sides.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer (ISSN 0017-9310); 28; 500-502
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    A review of hot wire anemometry in transonic flows (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present paper provides a review of hot wire anemometry for compressible flows, giving particular attention to the transonic flow problem. It is pointed out that the first and most important definitive work in hot wire anemometry for compressible flows was reported by Kovasznay (1953). The existence of three independent fluctuating modes in compressible flows for small perturbations was found, taking into account the vorticity mode, the entropy mode, and the sound-wave mode. A review of Kovasznays' method for supersonic flows is also presented, and advances reported by Markovin (1956) are examined. Attention is given to experiments conducted by Horstman and Rose (1977), a general solution to the hot wire problem at transonic conditions sought by Stainback et al. (1983), and some apparent problems.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Application of a fractional-step method to incompressible Navier-Stokes equations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A numerical method for computing three dimensional, time dependent incompressible flows is presented. The method is based on a fractional step, or time-splitting, scheme in conjunction with the approximate-factorization technique. The use of velocity boundary conditions for the intermediate velocity field leads to inconsistent numerical solutions. Appropriate boundary conditions for the intermediate velocity field are derived and tested. Numerical solutions for flow inside a driven cavity and over a backward-facing step are presented and compared with experimental data and other numerical results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 59; 308-323
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    Heat transfer in a real engine environment (1985)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The hot section facility at the Lewis Research Center was used to demonstrate the capability of instruments to make required measurements of boundary conditions of the flow field and heat transfer processes in the hostile environment of the turbine. The results of thermal scaling tests show that low temperature and pressure rig tests give optimistic estimates of the thermal performance of a cooling design for high pressure and temperature application. The results of measuring heat transfer coefficients on turbine vane airfoils through dynamic data analysis show good comparison with measurements from steady state heat flux gauges. In addition, the data trends are predicted by the STAN5 boundary layer code. However, the magnitude of the experimental data was not predicted by the analysis, particularly in laminar and transitional regions near the leading edge. The infrared photography system was shown capable of providing detailed surface thermal gradients and secondary flow features on a turbine vane and endwell.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Turbine Engine Hot Section Technology, 1985; p 139-150
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    Experimental observation of transition behavior on a flat plate (1985)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: In studying transition behavior a shock tube and tunnel were used to produce high temperatures, and thin-film platinum heat gauges were used to measure local heat flux as well as to detect the transition of the laminar boundary layer over a flat plate and a cone. Initial investigations were conducted in the hypersonic shock tunnel to obtain high-temperature information for the development of an ICBM nose cone. Shock Mach numbers as large as 50 with a temperature of 15,000 K after the incident wave were produced in the driven tube. Shock tubes are used to investigate the heat transfer over various surfaces to 2500 K for the development of future gas turbines.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Transition in Turbines; p 49-59
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    Turbulent solutions of equations of fluid motion (1985)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Some turbulent solutions of the unaveraged Navier-Stokes equations (equations of fluid motion) are reviewed. Those equations are solved numerically in order to study the nonlinear physics of incompressible turbulent flow. The three components of the mean-square velocity fluctuations are initially equal for the conditions chosen. The resulting solutions show characteristics of turbulence, such as the linear and nonlinear excitation of small-scale fluctuations. For the stronger fluctuations the initially nonrandom flow develops into an apparently random turbulence. The cases considered include turbulence that is statistically homogeneous or inhomogeneous and isotropic or anisotropic. A statistically steady-state turbulence is obtained by using a spatially periodic body force. Various turbulence processes, including the transfer of energy between eddy sizes and between directional components and the production, dissipation, and spatial diffusion of turbulence, are considered. It is concluded that the physical processes occurring in turbulence can be profitably studied numerically.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Transition in Turbines; p 95-160
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    Trends in computational capabilities for fluid dynamics (1985)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: Milestones in the development of computational aerodynamics are reviewed together with past, present, and future computer performance (speed and memory) trends. Factors influencing computer performance requirements for both steady and unsteady flow simulations are identified. Estimates of computer speed and memory that are required to calculate both inviscid and viscous, steady and unsteady flows about airfoils, wings, and simple wing body configurations are presented and compared to computer performance which is either currently available, or is expected to be available before the end of this decade. Finally, estimates of the amounts of computer time that are required to determine flutter boundaries of airfoils and wings at transonic Mach numbers are presented and discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Transonic Unsteady Aerodyn. and its Aeroelastic Appl.; 9 p
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    Progress and supercomputing in computational fluid dynamics; Proceedings of U.S.-Israel Workshop, Jerusalem, Israel, December 1984 (1985)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Description: Current developments and future trends in the application of supercomputers to computational fluid dynamics are discussed in reviews and reports. Topics examined include algorithm development for personal-size supercomputers, a multiblock three-dimensional Euler code for out-of-core and multiprocessor calculations, simulation of compressible inviscid and viscous flow, high-resolution solutions of the Euler equations for vortex flows, algorithms for the Navier-Stokes equations, and viscous-flow simulation by FEM and related techniques. Consideration is given to marching iterative methods for the parabolized and thin-layer Navier-Stokes equations, multigrid solutions to quasi-elliptic schemes, secondary instability of free shear flows, simulation of turbulent flow, and problems connected with weather prediction.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Flux limiters (1985)
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    Publication Date: 2019-06-28
    Description: It is well known that first order accurate difference schemes for the numerical solution of conservation laws produce results which suffer from excessive numerical diffusion, classical second order schemes, although giving better resolution, suffer from spurious oscillations. Recently much effect has been put into achieving high resolution without these oscillations, using a variety of techniques. Here one class of such methods, that of flux limiting, is outlined together with the TVD constraint used to ensure oscillation free solutions. Brief numerical comparisons of different limiting functions are also presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Numerical solution of the unsteady Navier-Stokes equation (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The construction and the analysis of nonoscillatory shock capturing methods for the approximation of hyperbolic conservation laws are discussed. These schemes share many desirable properties with total variation diminishing schemes, but TVD schemes have at most first-order accuracy, in the sense of truncation error, at extrema of the solution. In this paper a uniformly second-order approximation is constructed, which is nonoscillatory in the sense that the number of extrema of the discrete solution is not increasing in time. This is achieved via a nonoscillatory piecewise linear reconstruction of the solution from its cell averages, time evolution through an approximate solution of the resulting initial value problem, and averaging of this approximate solution over each cell.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-181173 , NAS 1.26:181173
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    Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel) (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-171977 , NAS 1.26:171977 , W-30746
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    Algorithms for the Euler and Navier-Stokes equations for supercomputers (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The steady state Euler and Navier-Stokes equations are considered for both compressible and incompressible flow. Methods are found for accelerating the convergence to a steady state. This acceleration is based on preconditioning the system so that it is no longer time consistent. In order that the acceleration technique be scheme-independent, this preconditioning is done at the differential equation level. Applications are presented for very slow flows and also for the incompressible equations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Pattern formation by particles settling in viscous flows (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Results are reported of several simulations of the motions of small objects in two-dimensional cellular flows performed to study the evolution of the distributions of particle flows over time in processes such as sedimentation. Stream functions are defined in the form of a Hamiltonian system for the particle motions, with inertial and particle acceleration being neglected. Conditions are found for which the particles will become trapped in an oscillatory motion or the particle orbits attain an oscillary motion. Various simulation images are provided to illustrate the usefulness of the technique for modeling fractal swarms.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Surface temperature distribution along a thin liquid layer due to thermocapillary convection (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The surface temperature distributions due to thermocapillary convections in a thin liquid layer with heat fluxes imposed on the free surface were investigated. The nondimensional analysis predicts that, when convection is important, the characteristics length scale in the flow direction L, and the characteristic temperature difference delta T sub o can be represented by L and delta T sub o approx. (A2Ma)/1/4 delta T sub R, respectively, where L sub R and delta sub R are the reference scales used in the conduction dominant situations with A denoting the aspect ratio and Ma the Marangoni number. Having L and delta sub o defined, the global surface temperature gradient delta sub o/L, the global thermocapillary driving force, and other interesting features can be determined. Numerical calculations involving a Gaussian heat flux distribution are presented to justify these two relations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: IAF PAPER 85-282
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    Near field pressure fluctuations of a circular jet (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The relationship between the evolution of vortices in a circular jet and the generation of fluctuating pressure was studied, using an apparatus consisting of a jet nozzle connected to a stagnation chamber with a fifth-order polynomial contraction. The data were digitized and computer-processed. The constant pressure contours near the jet shoow that the evolution of coherent structures is the source of pressure perturbations. The data obtained in the vicinity of the jet indicate that two length scales govern the decay of the fluctuating pressure. A thin hydrodynamic near-field extends about 1 instability wavelength from the jet edge, and pressure decays exponentially. A thick acoustic near-field takes about ten acoustic wavelengths to reach the far field. The pressure disturbances decay algebraically in this region.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    The non-Newtonian heat and mass transport of He 2 in porous media used for vapor-liquid phase separation (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: This investigation of vapor-liquid phase separation (VLPS) of He 2 is related to long-term storage of cryogenic liquid. The VLPS system utilizes porous plugs in order to generate thermomechanical (thermo-osmotic) force which in turn prevents liquid from flowing out of the cryo-vessel (e.g., Infrared Astronomical Satellite). An apparatus was built and VLPS data were collected for a 2 and a 10 micrometer sintered stainless steel plug and a 5 to 15 micrometer sintered bronze plug. The VLPS data obtained at high temperature were in the nonlinear turbulent regime. At low temperature, the Stokes regime was approached. A turbulent flow model was developed, which provides a phenomenological description of the VLPS data. According to the model, most of the phase separation data are in the turbulent regime. The model is based on concepts of the Gorter-Mellink transport involving the mutual friction known from the zero net mass flow (ZNMF) studies. The latter had to be modified to obtain agreement with the present experimental VLPS evidence. In contrast to the well-known ZNMF mode, the VLPS results require a geometry dependent constant (Gorter-Mellink constant). A theoretical interpretation of the phenomenological equation for the VLPS data obtained, is based on modelling of the dynamics of quantized vortices proposed by Vinen. In extending Vinen's model to the VLPS transport of He 2 in porous media, a correlation between the K*(GM) and K(p) was obtained which permits an interpretation of the present findings. As K(p) is crucial, various methods were introduced to measure the permeability of the porous media at low temperatures. Good agreement was found between the room temperature and the low temperature K(p)-value of the plugs.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-177075 , NAS 1.26:177075
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    Adapting a Navier-Stokes code to the ICL-DAP (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The results of an experiment are reported, i.c., to adapt a Navier-Stokes code, originally developed on a serial computer, to concurrent processing on the CL Distributed Array Processor (DAP). The algorithm used in solving the Navier-Stokes equations is briefly described. The architecture of the DAP and DAP FORTRAN are also described. The modifications of the algorithm so as to fit the DAP are given and discussed. Finally, performance results are given and conclusions are drawn.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178034 , ICASE-85-61 , NAS 1.26:178034
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    Active control of compressible flows on a curved surface (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize and unstable wave.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178018 , ICASE-85-52 , NAS 1.26:178018
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    Marching iterative methods for the parabolized and thin layer Navier-Stokes equations (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Downstream marching iterative schemes for the solution of the Parabolized or Thin Layer (PNS or TL) Navier-Stokes equations are described. Modifications of the primitive equation global relaxation sweep procedure result in efficient second-order marching schemes. These schemes take full account of the reduced order of the approximate equations as they behave like the SLOR for a single elliptic equation. The improved smoothing properties permit the introduction of Multi-Grid acceleration. The proposed algorithm is essentially Reynolds number independent and therefore can be applied to the solution of the subsonic Euler equations. The convergence rates are similar to those obtained by the Multi-Grid solution of a single elliptic equation; the storage is also comparable as only the pressure has to be stored on all levels. Extensions to three-dimensional and compressible subsonic flows are discussed. Numerical results are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-178028 , ICASE-85-60 , NAS 1.26:178028
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    Free vorticity field-boundary layer conversions: Effect of boundary configuration and scale (1985)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Progress was made on further flow visualization of vortex-leading edge interaction, in conjunction with characterization of the unsteady pressure field. The range of scale of an elliptical leading edge, relative to the incident primary vortex, was determined. The scale of the incident vortex was characterized in terms of mean shear layer parameters. An overview of the interaction mechanism for the range of thin to thick leading-edges is given. The interaction mechanism corresponding to the case where the incident vortex is above the leading-edge is given for hydrogen bubble wires well upstream of and at the tip of the leading edge. A sample of the instantaneous pressure distribution for the case where the incident vortex dives beneath the edge is presented. The effect of scale of the incident vortex relative to that of the leading-edge was examined. The circulation and length scale of the incident vortices in the street are being characterized.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-181265 , NAS 1.26:181265
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    Modelling of three-dimensional shock wave turbulent boundary layer interactions (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The accuracy of numerical computations of the three-dimensional sharp fin flow field using the Reynolds-averaged Navier-Stokes equations is examined. Computed flows are compared with a set of benchmark experiments at Mach 3 for two different Reynolds numbers. A detailed comparison is performed between experimental data and separate computational results for the three-dimensional sharp fin for a 10 deg fin angle in order to examine the accuracy of two different turbulence models. The computed surface pressure for the fin at a 20 deg angle is compared with recent experimental data. The computed yaw angle profiles are shown to be sensitive to the turbulence model. In the immediate vicinity of the surface, the calculated results using the Baldwin-Lomax (1978) model are in better agreement with the data than the Jones-Launder (1972) model. Within the inner portion of the boundary layer, both models tend to underpredict the yaw angle.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    The structure and characterization of air-assisted swirl atomizer sprays (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The detailed aerodynamic structure of air-assisted swirl atomizer sprays is investigated in this paper. In contrast to previously published papers on spray characterization, special emphasis is placed on the region near the atomizer exit where significant variation of the mean drop size and drop velocity occurs. Simple correlations are found for the spray mean drop size and some initial input parameters. Measurements of drop acceleration and deceleration can be well related to the line-of-sight variations in mean drop size and number density. It is found that the initial drop acceleration and spray dispersion cause the initial decrease of axial mean drop diameters and subsequent drop deceleration causes the increase of mean drop diameters.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 85-WA/HT-45
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    A comparison of three algebraic stress closures for combustor flow calculations (1985)
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    Publication Date: 2019-06-28
    Description: A comparison is made of the performance of two locally nonequilibrium and one equilibrium algebraic stress closures in calculating combustor flows. Effects of four different pressure-strain models on these closure models are also analyzed. The results show that the pressure-strain models have a much greater influence on the calculated mean velocity and turbulence field than the algebraic stress closures, and that the best mean strain model for the pressure-strain terms is that proposed by Launder, Reece and Rodi (1975). However, the equilibrium algebraic stress closure with the Rotta return-to-isotropy model (1951) for the pressure-strain terms gives as good a correlation with measurements as when the Launder et al. mean strain model is included in the pressure-strain model. Finally, comparison of the calculations with the standard k-epsilon closure results show that the algebraic stress closures are better suited for simple turbulent flow calculations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 85-WA/FE-3
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    Active control of compressible flows on a curved surface (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The effect of localized, time periodic surface heating and cooling over a curved surface is studied. This is a mechanism for the active control of unstable disturbances by phase cancellation and reinforcement. It is shown that the pressure gradient induced by the curvature significantly enhances the effectiveness of this form of active control. In particular, by appropriate choice of phase, active surface heating can completely stabilize an unstable wave.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: SAE PAPER 851856
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  • 94
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    On the structure of homogeneous turbulence (1985)
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    Publication Date: 2019-06-28
    Description: Full turbulence simulation has been conducted of homogeneous turbulence subject to irrotational strains and under relaxation from these. Effects of the mode and strength of the imposed mean strain rate on the Reynolds stress, dissipation and vorticity fields are analyzed, yielding new insight. Tensorial models for the relaxation process are proposed for the vorticity dissipation and Reynolds stress anisotropies.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 95
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    Unsteady turbulent boundary layers - Some effects of abrupt free-stream velocity changes (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The response of a turbulent boundary layer to abrupt changes in free-stream velocity is studied. Streamwise velocity measurements are examined during the abrupt events and after them, as the flow relaxes to its equilibrium condition. The measured velocity field is found to be in good agreement with the analytic solution of the Stokes equation for boundary conditions describing abrupt changes. While the flow recovers to its equilibrium state, changes in integral, boundary-layer parameters scale on the local free-stream time of flight.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 96
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    An experimental and computational study of turbulent boundary layers in oscillating flows (1985)
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    Publication Date: 2019-06-28
    Description: An experimental-computational study of the behavior of turbulent boundary layers for oscillating air flows over a plane surface with a small favorable mean pressure gradient is described. Experimental data were obtained for boundary layers generated on the test section wall of a new type of facility that produces a mean flow velocity with a superposed sinusoidal component over a wide frequency range. Experimental results for unsteady velocity profiles and turbulence intensity obtained from hot wire measurements at a fixed stream-wise position on the surface are presented for frequencies ranging from 5 to 21 Hz. Numerical predictions were obtained using an unsteady boundary layer computational code and the Cebeci-Smith and Glushko turbulence models. Predicted quantities related to unsteady velocity profiles exhibit fair agreement with experiment when the Cebeci-Smith model is used.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 97
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    Coherent structures in a turbulent mixing layer - A comparison between direct numerical simulations and experiments (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An eduction scheme has been developed in an attempt to determine the characteristics of large-scale vortical structures in a turbulent mixing layer. This analysis scheme has been applied to a set of experimental data taken in a new, larger mixing layer facility designed to minimize boundary and resonance effects. A similar scheme has been developed to apply to the results of a direct numerical simulation of a temporally growing mixing layer. A comparison of the two approaches shows important similarities in the coherent structures. The numerical simulations indicate that low levels of coherent forcing can dramatically change the evolution of the mixing layer. In the absence of such forcing, the numerical simulations and experiments show a lack of regularity in the transverse position, spacing, amplitude, shape and spanwise coherence of the large-scale vortical structures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 98
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    Entrainment region phenomena for a large plane shear layer (1985)
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    Publication Date: 2019-06-28
    Description: The subatmospheric test section of the present free shear layer facility allows the entrainment air to be introduced with a negligible disturbance level. The very low frequency oscillations, which are prominently observed in the entrainment stream and which are present throughout the shear layer, are attributed to an inherent instability in the transition from a boundary layer to a free shear layer state. The basic features of the disturbance field are documented herein.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 99
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    The behaviour of turbulence anisotropy through shock waves and expansions (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A second order closure has been implemented in an implicit Navier-Stokes solver to study the behavior of the Reynolds stresses under the influence of severe pressure gradients. In the boundary layer zone, the strongly sheared character of the mean flow dominates the turbulence generation mechanisms. However, the pressure gradients play also a very important role for these processes, but at different locations within the boundary layer. This aspect may be emphasized by the analysis of turbulence anisotropy through shock waves and expansions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 100
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    Calculation of three-dimensional boundary layers on rotating turbine blades (1985)
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    Publication Date: 2019-06-28
    Description: An assessment has been made of the applicability of a three dimensional boundary layer analysis to the calculation of heat transfer and streamline flow patterns on the surfaces of both stationary and rotating turbine passages. In support of this effort, an analysis has been developed to calculate a general nonorthogonal surface coordinate system for arbitrary three dimensional surfaces and also to calculate the boundary layer edge conditions for compressible flow using the surface Euler equations and experimental pressure distributions. Using available experimental data to calibrate the method, calculations are presented for the endwall, and suction surfaces of a stationary cascade and for the pressure surface of a rotating turbine blade. The results strongly indicate that the three dimensional boundary layer analysis can give good predictions of the flow field and heat transfer on the pressure, suction, and endwall surfaces in a gas turbine passage.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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