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  • Inorganic Chemistry  (1.816)
  • Cell & Developmental Biology  (1.471)
  • FLUID MECHANICS AND HEAT TRANSFER  (655)
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  • 1
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    The Capillary Pumped Loop (CPL) GAS experiment G-471 (1986)
    In:  CASI
    Details
    Publikationsdatum: 2009-11-16
    Beschreibung: The Capillary Pumped Loop (CPL) experiment, G-471 is a thermal control system with high density heat acquisition and transport capability. The CPL consists of two capillary pumped evaporators with integral heaters, a fluid loop charged with ammonia (NH3), a condenser plate (heat sink), and various control electronics. The purpose of the experiment is to demonstrate the capability of a capillary pumped system under zero gravity conditions for use in the thermal control of large scientific instruments, advanced orbiting spacecraft, and space station components.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: The 1985 Get Away Special Experimenter's Symposium; p 237-253
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  • 2
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    Thermocapillary flow and gaseous convection in microgravity: Results from GAS payload G-0518 (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-12
    Beschreibung: Thermocapillary flow and gaseous convection in microgravity were investigated in GAS payload G-0518 during Space Shuttle Mission 41-D. A cylinder of paraffin was supported and heated differentially from its ends to induce a melt from solid to liquid and drive thermocapillary flow in the resulting liquid phase. Laminar thermocapillary flow was observed in the liquid paraffin and found to show a transition to time-dependent oscillatory motion at a Marangoni number of about Ma = 34000 with a period of approximately T = 8 seconds. In addition, free convection in a gas in microgravity was observed for the first time. The gaseous convection was caused by the thermal and/or velocity boundary layers present at the heater-liquid interface. Oscillation occurred in the gaseous convection simultaneously with those in the liquid, implying the two are strongly coupled. The gaseous convection may be driven by coupled thermocapillary flow/thermal expansion convection or microgravity bouyancy convection.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Goddard Space Flight Center The 1985 Get Away Special Experimenter's Symposium; p 293-301
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  • 3
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    GAS payload no. G-025: Study of liquid sloshing behaviour in microgravity (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-12
    Beschreibung: The Get Away Special (GAS) G-025, which flew on shuttle Mission 51-G, examined the behavior of a liquid in a tank under microgravity conditions. The experiment is representative of phenomena occurring in satellite tanks with liquid propellants. A reference fluid in a hemispherical model tank will be subjected to linear acceleration inputs of known levels and frequencies, and the dynamic response of the tank liquid system was recorded. Preliminary analysis of the flight data indicates that the experiment functioned perfectly. The results will validate and refine mathematical models describing the dynamic characteristics of tank-fluid systems. This will in turn support the development of future spacecraft tanks, in particular the design of propellant management devices for surface tension tanks.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Goddard Space Flight Center The 1985 Get Away Special Experimenter's Symposium; p 165-176
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  • 4
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    Water ball collision (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-12
    Beschreibung: What happens if a stainless steel ball hits a water ball in the weightless space ot the Universe? In other words, it was the objective of our experiments in the Space to observe the surface tension of liquid by means of making a solid collide with a liquid. Place a small volume of water between 2 glass sheets to make a thin water membrane: the 2 glass sheets cannot be separated unless an enormous force is applied. It is obvious from this phenomenom that the surface tension of water is far greater than presumed. On Earth, however, it is impossible in most cases to observe only the surface tension of liquid, because gravity always acts on the surface tension. Water and stainless steel balls were chosen the liquid and solids for the experiments. Because water is the liquid most familiar to us, its properties are well known. And it is also of great interest to compare its properties on the Earth with those in the weightless space.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Goddard Space Flight Center The 1985 Get Away Special Experimenter's Symposium; p 81-84
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  • 5
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    Shuttle Continuous Open Wind Tunnel (SCOWT) (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The aerodynamic and heat transfer coefficients are studied within the range of thermo-fluid-dynamic conditions experienced by a satellite during Tethered Satellite System (TSS) atmospheric flights. The gasdynamic processes occuring downstream of the bow wave standing in front of the satellite are also studied. The knowledge of the chemistry and physics of the upper atmosphere related to satellite aerothermodynamics is furthered. The existence of an overshooting of the air drag coefficient of the sphere in the transition regime is validated. A complete set of measurements is performed in order to provide the data base to develop and validate theoretical models of free molecule transition flow fields.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA, Washington Applications of Tethers in Space. Workshop Proceedings, Vol. 2; p 225-249
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  • 6
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    Fluid behavior in microgravity (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-06-11
    Beschreibung: An experiment designed to study some fundamental aspects of microgravity fluid dynamics has been built and is scheduled for flight. The purpose of the experiment is to investigate differences in behavior of wetting and nonwetting fluid systems at low Bond numbers. Methods were developed to determine liquid quantity, estimate vapor contact area and measure liquid layer thickness. Both the responses of the fluid systems to external perturbations and the transfer of liquid through a connection between two containers can be studied.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Goddard Space Flight Center The 1985 Get Away Special Experimenter's Symposium; p 33-40
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  • 7
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    An analysis of ullage heat transfer in the orbital refueling system (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The Orbital Refueling System was an experiment flown on Shuttle Mission STS 41-G in October, 1984. Liquid hydrazine fuel was transferred back and forth from one spherical bladder tank to another using pressurized nitrogen as the driving force. Compressive heating of the ullage gas in the receiving tank could lead to a hazardous situation if any hydrazine leaked through to the ullage side of the bladder and was heated above about 175 F, where it can undergo spontaneous exothermic decomposition. Early analysis of the flight data indicated that the ullage compression process was much closer to an isothermal than an adiabatic one. In this study, a thorough review of the pertinent literature was used to make an a priori best-estimate for the ullage gas heat transfer coefficient (defining the Nusselt Number as a function of Reynolds and Rayleigh Numbers). Experimental data from the flight were analyzed in detail. It is evident that there is considerably more heat transfer than can be accounted for by conduction alone, but the observed increases do not correlate well with Reynolds Number, Rayleigh Number or vehicle acceleration. There are large gaps in the present understanding of convective heat transfer in closed containers with internal heat generation, especially in the presence of vibrations or other random disturbances. A program of experiments to fill in these gaps is suggested, covering both ground and orbital environments.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Johnson Space Center NASA/American Society for Engineering Educati; NASA. Johnson Space
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  • 8
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    Flow phenomena peculiar to calculation of compressible turbulent boundary layers (1977)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: Calculation procedures for compressible turbulent boundary layers were based upon techniques, modeling constants, etc., developed originally for the low speed case. Significant differences and new or altered physics which occur in the compressible case were considered, as compared with the low speed situation. Possible pitfalls and sources of inaccuracy in the calculations were indicated.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 9-46
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  • 9
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    Summary of calculation procedures for nonsimilar two- and three-dimensional compressible turbulent boundary layers (finite difference, finite element and weighted residual methods), appendix (1977)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: This numerical prediction summary indicates the wide variety of such procedures which are available. Most procedures have detailed user manuals, and in many cases the codes are available. Many of the special effects treated by various methods (such as nonequilibrium or equilibrium chemistry, transition, roughness etc.) are indicated.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 69-78
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  • 10
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    Calculation of three-dimensional compressible turbulent boundary layers (1977)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: From comparisons of high speed data with low speed closure procedures using variable mean density, there does not appear to be any appreciable influence of compressibility upon turbulent shear stress modeling in compressible turbulent boundary layers, even for extreme cases such as Mach 14 to 20 with a change in density across the layer of up to a factor of 100. Other evidence of apparent lack of compressibility caused new physics which may alter the shear stress for the compressible boundary layer cases including: (1) fluctuation Mach number was generally less than 1; (2) the shear stress distribution through the boundary layer was not a function of Mach number for zero pressure gradient flows; (3) the Morkovin hypothesis was valid up to Mach 5 (based on fluctuation data); (4) profile N power was not a function of Mach number, at least up to Mach 10; and (5) the nondimensional burst period was approximately the same as that for low speed.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 47-68
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  • 11
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    Equations and closure methods (1977)
    In:  CASI
    Details
    Publikationsdatum: 2006-01-16
    Beschreibung: Basic differential equations governing compressible turbulent boundary layer flow are reviewed, including conservation of mass and energy, momentum equations derived from Navier-Stokes equations, and equations of state. Closure procedures were broken down into: (1) simple or zeroth-order methods, (2) first-order or mean field closure methods, and (3) second-order or mean turbulence field methods.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Calculation Methods for Compressible Turbulent Boundary Layers, 1976; p 6-8
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  • 12
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    Materials considerations in the design of a metal-hydride heat pump for an advanced extravehicular mobility unit (1986)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A metal-hydride heat pump (HHP) has been proposed to provide an advanced regenerable nonventing thermal sink for the liquid-cooled garment worn during an extravehicular activity (EVA). The conceptual design indicates that there is a potential for significant advantages over the one presently being used by shuttle crew personnel as well as those that have been proposed for future use with the space station. Compared to other heat pump designs, a HHP offers the potential for extended use with no electrical power requirements during the EVA. In addition, a reliable, compact design is possible due to the absence of moving parts other than high-reliability check valves. Because there are many subtleties in the properties of metal hydrides for heat pump applications, it is essential that a prototype hydride heat pump be constructed with the selected materials before a committment is made for the final design. Particular care must be given to the evaporator heat exchanger worn by the astronaut since the performance of hydride heat pumps is generally heat transfer limited.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Johnson Space Center NASA/American Society for Engineering Educati; NASA. Johnson Space
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  • 13
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    Condensation heat transfer under a microgravity environment (1986)
    In:  CASI
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    Publikationsdatum: 2006-02-14
    Beschreibung: A description of the condensation heat transfer process in microgravity is given. A review of the literature is also reported. The most essential element of condensation heat transfer in microgravity is the condensate removal mechanism. Two mechanisms for condensate removal are analyzed by looking into two problems. The first problem is concerned with film condensation on a flat porous plate with the condensate being removed by suction at the wall. The second problem is an analytical prediction of the heat transfer coefficient for condensing annular flows with the condensate film driven by the vapor shear. It is concluded that both suction and vapor shear can effectively drain the condensate to ensure continuous operation of the condensers operated under a microgravity environment. It is recommended that zero-g flight experiments be carried out to verify the prediction made in the present report. The results contained in this report should also aid in the design of future space condensers.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Johnson Space Center NASA/American Society for Engineering Educati; NASA. Johnson Space
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  • 14
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    Flow regimes in a shallow rotating cylindrical annulus with temperature gradients imposed on the horizontal boundaries (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Experimental flow regime diagrams are determined for a new rotating cylindrical annulus configuration which permits a measure of control over the internal vertical temperature gradient. The new annulus has radial temperature gradients imposed on plane horizontal thermally conducting endwalls (with the cylindrical sidewalls as insulators) and is considered to be more relevant to atmospheric dynamics studies than the classical cylindrical annulus. Observations have revealed that, in addition to the axisymmetric flow and nonaxisymmetric baroclinic wave flow which occur in the classical annulus, two additional nonaxisymmetric flow types occur in the new annulus: boundary-layer thermal convection and deep thermal convection. Flow regime diagrams for three different values of the imposed vertical temperature difference are presented, and explanations for the flow transitions are offered. The new annulus provides scientific backup for the proposed Atmospheric General Circulation Experiment for Spacelab. The apparatus diagram is included.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Fluid Mechanics (ISSN 0022-1120); 172; 401-418
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  • 15
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    The special relativistic shock tube (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The shock-tube problem has served as a popular test for numerical hydrodynamics codes. The development of relativistic hydrodynamics codes has created a need for a similar test problem in relativistic hydrodynamics. The analytical solution to the special relativistic shock-tube problem is presented here. The relativistic shock-jump conditions and rarefaction solution which make up the shock tube are derived. The Newtonian limit of the calculations is given throughout.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Fluid Mechanics (ISSN 0022-1120); 171; 365-375
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  • 16
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    Measurement and prediction of model-rotor flowfields (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 23; 843-851
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  • 17
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    Scaling relations for heating during gliding entry at parabolic speed (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The scaling relations presently derived illustrate the influence of ballistic coefficient and L/D primary vehicle parameters on the peak heating rate and total heating/unit area for gliding entry of the earth atmosphere at parabolic speed. Comparisons with stagnation-point and windward centerline laminar and turbulent heating during three Space Shuttle flights are presented. It is found that total heat input/unit area is reduced by decreasing both of the primary vehicle parameters.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 2047-204
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  • 18
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    Quadratic resonance in the three-dimensional oscillations of inviscid drops with surface tension (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The moderate-amplitude, three-dimensional oscillations of an inviscid drop are described in terms of spherical harmonics. Specific oscillation modes are resonantly coupled by quadratic nonlinearities caused by inertia, capillarity, and drop deformation. The equations describing the interactions of these modes are derived from the variational principle for the appropriate Lagrangian by expressing the modal amplitudes to be functions of a slow time scale and by preaveraging the Lagrangian over the time scale of the primary oscillations. Stochastic motions are predicted for nonaxisymmetric deformations starting from most initial conditions, even those arbitrarily close to the axisymmetric shapes. The stochasticity is characterized by a redistribution of the energy contained in the initial deformation over all the degrees of freedom of the interacting modes.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 2788-279
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  • 19
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    Numerical experiments of axisymmetric flow in a nonuniform gravitational field (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 1483-148
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  • 20
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    Is Navier-Stokes turbulence chaotic? (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Whether turbulent solutions of the Navier-Stokes equations are chaotic is considered. Initially neighboring solutions for a low-Reynolds-number fully developed turbulence are compared. The turbulence is sustained by a nonrandom time-independent external force. The solutions separate exponentially with time, having a positive Liapunov characteristic exponent. Thus the turbulence is characterized as chaotic.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 1453-145
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  • 21
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    A theoretical model for the annular jet instability (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The instability of an annular gas-core liquid jet is modeled theoretically by treating the liquid layer as a membrane moving under the influences of its own inertia, surface tension, and the gaseous hydrostatic pressure difference between its two sides. Essential physical mechanisms are reconstructed without making any attempt to fit experimental data with model constants. The results compare favorably with those of experiment.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 2076-208
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  • 22
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    Experiments on annular liquid jet instability and on the formation of liquid shells (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Experiments are described in which such a flow is generated by an annular nozzle operated at fairly specific conditions. It is shown that periodic, axisymmetric oscillations arise spontaneously within the cylindrical sheet emerging from the nozzle and grow with such rapidity along the axial dimension that a sealing-off and encapsulation of the core gas occurs within a few jet diameters. This is closely followed by a pinchoff of the liquid between adjacent bubbles. The liquid shells set free thereby assume spherically symmetric form under capillary forces, and each contains a precisely uniform measure of gas and of liquid on account of the extremely high frequency-stability of the process. Description is given of the fluid dynamic processes by which the shells are formed, and mention is made of exploiting the instability for the production of rigid shells for technological applications.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 2086-209
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  • 23
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    Turbulent Reynolds analogy factors of stacked large-eddy breakup devices (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Direct measurements are made of turbulent Reynolds analogy factors, referenced to a flat plate, for turbulent boundary layer flows altered by stacked arrays of large eddy breakup devices (LEBUs). These are of interest as drag reducers when inserted into a boundary layer transverse to the flow. The data thus obtained furnish evidence that heat transfer, skin friction drag, and LEBU performance factors in low Reynolds number flows are sensitive to flow history. Attention is given to the apparatus and measurement procedures used.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Spacecraft and Rockets (ISSN 0022-4650); 23; 348-350
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  • 24
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    Coupling conditions for integrating boundary layer and rotational inviscid flow (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The matching of a boundary layer and a rotational inviscid flow is reexamined by extending the Johnson and Sockol (1979) coupling conditions to include the case where the boundary layer solution includes the second-order effects of the freestream vorticity and the total temperature gradient. It is pointed out that two of the three conditions are not independent. If the boundary layer solution satisfies the appropriate momentum and energy integral equations, it follows that the imposition of the normal mass flux condition insures that the conditions on a normal flux of streamwise momentum and total enthalpy will also be satisfied.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 1033-103
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  • 25
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    A new approach for solving the three-dimensional steady Euler equations. I - General theory (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The present iterative procedure combines the Clebsch potentials and the Munk-Prim (1947) substitution principle with an extension of a semidirect Cauchy-Riemann solver to three dimensions, in order to solve steady, inviscid three-dimensional rotational flow problems in either subsonic or incompressible flow regimes. This solution procedure can be used, upon discretization, to obtain inviscid subsonic flow solutions in a 180-deg turning channel. In addition to accurately predicting the behavior of weak secondary flows, the algorithm can generate solutions for strong secondary flows and will yield acceptable flow solutions after only 10-20 outer loop iterations.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Computational Physics (ISSN 0021-9991); 60; 23-61
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  • 26
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    Numerical analysis of confined recirculating gas-solid turbulent flows (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Particle dispersion in confined recirculating turbulent flows has been investigated numerically. The present computational scheme utilizes Eulerian forms of the governing equations and allows two-way coupling between gas and solid phases. A recently developed two-phase closure model based on the multiple-scale turbulence model was used for the estimation of turbulent viscosities and diffusivities. For the particle size and loading considered in this study, the effect of particulate phase on the conveying gas is small, the nonequilibrium between the two phases is significant. Effects of recirculation, expanded chamber size and secondary annular jet momentum on the particle mixing rate are also investigated. In general, the present numerical results are in reasonably good agreement with the available experimental data.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 27
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    Two-phase flows and heat transfer within systems with ambient pressure above the thermodynamic critical pressure (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: In systems where the design inlet and outlet pressure P sub amb are maintained above the thermodynamic critical pressure P sub c, it is often assumed that heat and mass transfer are governed by single-phase relations and that two-phase flows cannot occur. This simple rule of thumb is adequate in many low-power designs but is inadequate for high-performance turbomachines, boilers, and other systems where two-phase regions can exist even though P sub amb P sub c. Heat and mass transfer and rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two-phase zone can differ significantly from those for a single-phase zone. By using a laminar, variable-property bearing code and a rotating boiler code, pressure and temperature surfaces were determined that illustrate nesting of a two-phase region within a supercritical pressure region. The method of corresponding states is applied to bearings with reasonable rapport.
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    Forced convection heat transfer to air/water vapor mixtures (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Heat transfer coefficients were measured using both dry air and air/water vapor mixtures in the same forced convection cooling test rig (jet array impingement configurations) with mass ratios of water vapor to air up to 0.23. The primary objective was to verify by direct experiment that selected existing methods for evaluation of viscosity and thermal conductivity of air/water vapor mixtures could be used with confidence to predict heat transfer coefficients for such mixtures using as a basis heat transfer data for dry air only. The property evaluation methods deemed most appropriate require as a basis a measured property value at one mixture composition in addition to the property values for the pure components.
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    Implicit solution methods in computational fluid dynamics (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A class of implicit finite difference schemes of the Beam and Warming approximate factorization type will be addressed. The development and analysis of various aspects of this class of schemes will be given along with the motivations behind many of the choices. Various acceleration and efficiency modifications such as matrix reduction, diagonalization and flux split schemes will be presented. The methods are demonstrated in fully vectorized codes for a CRAY type architecture. The emphasis will be on the Euler equations in generalized coordinates.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Applied Numerical Mathematics (ISSN 0168-9274); 2; 441-474
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    Distribution of resistive body-force in curved free-surface flow (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The customary procedure for including resistive effects in turbulent hydraulic and stratified atmospheric flows is to integrate the empirically-known boundary shears over the entire wetted boundary of a thin fluid slab. A resistive body-force is then assumed to exist everywhere in each slab to replace the boundary shearing force. For the classical Saint-Venant (1871) model, this body-force can be shown to have a constant distribution in the vertical direction, and therefore can be evaluated for use in the momentum differential equation. In the newer Dressler theory (1978), however, for unsteady flow over curved beds, it is proved here that a constant body-force distribution is not possible. Its variable distribution is determined as well as its magnitude for use in the curved-flow equations. This variable distribution acts to produce an equal resultant in every thin layer of fluid parallel to the bed in an angular wedge over the curved channel bed. The new curved-flow equations are therefore extended to include resistive effects.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Mathematical Methods in the Applied Sciences (ISSN 0170-4214); 8; 4, 19; 492-501
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    Numerical study of sink-flow boundary layers (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Direct numerical simulations of sink-flow boundary layers, with acceleration parameters K between 1.5 x 10 to the -6th and 3.0 x 10 to the -6th, are presented. The three-dimensional, time-dependent Navier-Stokes equations are solved numerically, using a spectral method, with about one million degrees of freedom. The flow is assumed to be statistically steady, and self-similar. A multiple-scale approximation and periodic conditions are applied to the fluctuations. The turbulence is studied using instantaneous and statistical results. Good agreement with the experiments of Jones and Launder (1972) is observed. The two effects of the favorable pressure gradient are to extend the logarithmic layer, and to alter the energy balance of the turbulence near the edge of the boundary layer. At low Reynolds number the logarithmic layer is shortened and slightly displaced, but wall-layer streaks are present even at the lowest values of R(theta) for which turbulence can be sustained. Large quiescent patches appear in the flow. Relaminarization occurs at K = 3.0 x 10 to the -6th, corresponding to a Reynolds number R(theta) of about 330.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Fluid Mechanics (ISSN 0022-1120); 172; 307-328
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    On the possibility of diffusionally driven oscillations in two component gas bubbles in fluids (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The problem of an isolated, stationary, two-component gas bubble in a fluid is analyzed. The appropriate governing equations, and an approximate version of these equations, for this model system are reviewed. The qualitative differences in bubble dissolution behavior between single- and two-component gas bubbles are elucidated. In particular, it is demonstrated that in the latter case the gas bubble radius may exhibit extrema as a function of time for certain values of the controlling parameters. The conditions under which these extrema may occur, and the maximum number of extrema which are permitted are elucidated.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Chemical Engineering Science (ISSN 0009-2509); 41; 9, 19; 2333-234
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    Oscillations of a viscous compound drop (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The effect of viscosity on normal mode oscillations of a compound drop is determined for a range of values of the viscosity, and the effect of a host medium is considered. The general form of the dispersion relation is derived, and numerical values are obtained for the case of an annular liquid region composed of silicon oil and with the core and host regions taken to be air. Results indicate that the sloshing mode of the compound drop is more damped than the bubble mode.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 3481-348
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  • 34
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    Multiple-scale turbulence model in confined swirling jet predictions (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A recently developed multiple-scale turbulence model which attempts to circumvent the deficiencies of earlier models by taking nonequilibrium spectral energy transfer into account is presented. The model's validity is tested by predicting the confined swirling coaxial jet flow in a sudden expansion. It is noted that, in order to account for anisotropic turbulence, a full Reynolds stress model is required.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 1717-171
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  • 35
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    Modeling of transition and surface roughness effects in boundary-layer flows (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Experiments were carried out to examine the influence of three-dimensional, stochastic roughness on the growth of incompressible turbulent boundary layers, as well as the effect of streamwise pressure gradients and freestream turbulence intensity on smooth-wall boundary-layer transition. The modeling of these effects in a two-dimensional boundary-layer computation program was examined with the help of the experiments. A model for surface roughness was developed that relates directly measurable statistical parameters quantifying the roughness geometry to the aerodynamic effects. This model should be valid for a limited class of surfaces found on turbomachinery blading and in other engineering applications. Commonly used criteria for the transition onset performed poorly and presumably need to be modified to account for other factors influencing the process.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 1642-164
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  • 36
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    Large volume water sprays for dispersing warm fogs (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A new method for dispersing of warm fogs which impede visibility and alter schedules is described. The method uses large volume recycled water sprays to create curtains of falling drops through which the fog is processed by the ambient wind and spray-induced air flow; the fog droplets are removed by coalescence/rainout. The efficiency of this fog droplet removal process depends on the size spectra of the spray drops and optimum spray drop size is calculated as between 0.3-1.0 mm in diameter. Water spray tests were conducted in order to determine the drop size spectra and temperature response of sprays produced by commercially available fire-fighting nozzles, and nozzle array tests were utilized to study air flow patterns and the thermal properties of the overall system. The initial test data reveal that the fog-dispersal procedure is effective.
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    Liquid fuel spray processes in high-pressure gas flow (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Atomization of single liquid jets injected downstream in high pressure and high velocity airflow was investigated to determine the effect of airstream pressure on mean drop size as measured with a scanning radiometer. For aerodynamic - wave breakup of liquid jets, the ratio of orifice diameter D sub o to measured mean drop diameter D sub m which is assumed equal to D sub 32 or Sauter mean diameter, was correlated with the product of the Weber and Reynolds numbers WeRe and the dimensionless group G1/square root of c, where G is the gravitational acceleration, 1 the mean free molecular path, and square root of C the root mean square velocity, as follows; D sub o/D sub 32 = 1.2 (WeRe) to the 0.4 (G1/square root of c) to the 0.15 for values of WeRe 1 million and an airstream pressure range of 0.10 to 2.10 MPa.
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  • 38
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    Application of the method of lines for solution of the Navier-Stokes equations using nonuniform grid distributions (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The method of lines is investigated for the numerical solution of the stream function and velocity form of the Navier-Stokes equations on nonuniform grids. Stiffness characteristics of a linear one-dimensional model equation are examined to establish the feasibility of applying the method to the volicity equation in two dimensions. It is observed that the transformed governing equations in computational domain become stiffer with increasing the number of grid points and the differencing technique affects the stiffness characteristics. The results demonstrate that the method of lines under certain circumstances is highly suitable for the numerical solution of physical problems on domains covered with variable grids.
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    Computation of nonstationary strong shock diffraction by curved surfaces (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A two-dimensional, high resolution shock-capturing algorithm was used on a supercomputer to solve Eulerian gasdynamic equations in order to simulate nonstationary strong shock diffraction by a circular arc model in a shock tube. The hypersonic Mach shock wave was assumed to arrive at a high angle of incidence, and attention was given to the effect of varying values of the ratio of specific heats on the shock diffraction process. Details of the conservation equations of the numerical algorithm, written in curvilinear coordinates, are provided, and model output is illustrated with the results generated for a Mach shock encountering a 15 deg circular arc. The sample graphics include isopycnics, a shock surface density profile, and pressure and Mach number contours.
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    Nonlinear critical layers eliminate the upper branch of spatially growing Tollmien-Schlichting waves (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: This letter is concerned with the effect of nonlinear critical layers on spatially growing Tollmien-Schlichting waves in a Blasius boundary layer. It is shown that they effectively eliminate the upper branch of the neutral stability curve predicted by strictly linear theory.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 2344
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    The generation of capillary instabilities on a liquid jet (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The coupling between imposed disturbances and capillary instabilities on a liquid jet is examined. It is shown that in most physical situations the forcing produces neutral waves, which can then turn into growing waves as the profile relaxes or may be amplified nonlinearly by a mechanism of the type considered by Akylas and Benney (1980). The effectiveness of the coupling is expressed quantitatively by numerically computed values of the 'coupling coefficient'.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Fluid Mechanics (ISSN 0022-1120); 168; 479-500
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    On symmetric and upwind TVD schemes (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The performance of the upwind and symmetric total variation diminishing (TVD) schemes in viscous and inviscid airfoil steady-state calculations is considered, and the extension of the implicit second-order-accurate TVD scheme for hyperbolic systems of conservative laws in curvilinear coordinates is discussed. For two-dimensional steady-state applications, schemes are implemented in a conservative noniterative alternating direction implicit form, and results illustrate that the algorithm produces a fairly good solution for an RAE2822 airfoil calculation. The study demonstrates that the symmetric TVD scheme is as accurate as the upwind TVD scheme, while requiring less computational effort than it.
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    Higher-order flux difference splitting schemes for the Euler equations using upstream interpolations (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A class of explicit two time-level, 2p + 1 space-point, (2p 1)-th order, upwind-biased flux difference splitting schemes are proposed for the numerical advection based on Lagrange's interpolation, and the method is an accord with the physical domain of dependence. A normalized Jacobian coefficient matrix is introduced to convert the schemes to hyperbolic systems of conservation laws, and approaches to make the higher-order schemes total variation stable are discussed. Accuracy and stability of the present schemes are examined, and implicit total variation diminishing schemes are developed for steady-state calculations.Application to gasdynamic problems for both steady and unsteady flows covering a wide range of Mach numbers is considered, and results for a blast wave passing a cylinder, and head-on collision of two blast waves over a circular arc, are presented. The flow patterns were found to be symmetric, and good resolution of flow structures was obtained.
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    Thermal response of integral, multicomponent composite thermal protection systems (1986)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Spacecraft and Rockets (ISSN 0022-4650); 23; 420-427
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  • 45
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    Convective and absolute instability of a viscous liquid jet (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The effect of viscosity on the capillary instability of a liquid jet is examined. The critical Weber number for convective instability is determined as a function of Reynolds number and comparison is made with the inviscid limit. It is shown that certain waves that are neutral in the inviscid case exhibit growth for finite Reynolds numbers.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 952-954
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    Free boundary shape of a convectively cooled solidified region (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The two-dimensional steady-state shape of a solidified region, such as a frost layer, was determined analytically for formation on a plate that is convectively cooled. The nonuniform shape of the layer is produced by exposure to a spatially nonuniform distribution of radiant energy. For high convective cooling the cooled wall approaches a uniform temperature, and an exact solution is obtained for the free boundary shape. For a lesser amount of convective cooling, the variation in temperature along the cooled boundary is treated by a boundary perturbation method. Some illustrative examples are given that show the effects of nonuniform heating and the magnitude of convective heat transfer at the cooled wall. Only one boundary condition is approximated by the perturbation solution; all of the other boundary conditions are satisfied exactly. The calculated results given here were found to satisfy the approximate boundary condition within a very small error.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: International Journal of Heat and Mass Transfer (ISSN 0017-9310); 29; 309-315
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    Boundary perturbation method for free boundary problem in convectively cooled continuous casting (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Novel mathematical techniques are here used to treat general boundary conditions in convectively cooled continuous ingot casting problems, applying a constant convective heat transfer coefficient at the ingot sides (so that the temperature distribution along the sides is unknown). The problem is first inverted to treat the physical coordinates as dependent variables of temperature and heat flow, mapping the ingot into a region that is nearly rectangular. A boundary perturbation method is then used to obtain an analytical solution in this near-rectangular region. Solidification interface shapes depend on two dimensionless parameters: one is a function of the casting velocity, while the other is dependent on the convective heat transfer coefficient at the cooled wall.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 108; 230-234
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    An experimental study using flow visualization on the effect of an acoustic field on heat transfer from spheres (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The physical mechanisms responsible for the heat transfer process in a thermal-acoustic field were investigated using the technique of holographic interferometry for flow visualization. Experimental results were obtained with sound pressure levels in the range of 120 to 150 decibels, relative to a pressure of 0.0002 dynes/sq cm. Steady state laminar flow was observed when the vibrational Reynolds number was below 400; separated flow was observed when it was above 400. In the presence of a horizontal sound field, the data indicate that the relation between the vibrational Nusselt number, Nu(v) and the vibrational Reynolds number, Re(v) is given by Nu(v) = Re(v) exp 0.22. In the presence of a vertical sound field, the corresponding relation is Nu(v) = Re(v) exp 0.15.
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    Turbulence modeling (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A survey designed to provide an introduction to the subject of turbulence modeling, and to explain the need for such models is given. The subject is developed along chronological lines since this provides a logical development plan and also because it then moves from relatively simple phenomenological models through more complicated procedures and ultimately to the subject of large-eddy simulation.
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    Turbulent solutions of the Navier-Stokes equations (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Analytical and numerical approaches to the mechanics of turbulent flow are examined in a general introduction and illustrated with graphs. Topics discussed include the averaged and unaveraged basic equations, numerical solutions and methods, homogeneous fluctuations and turbulence with no mean flow, uniformly sheared fluctuations and turbulence, inhomogeneous fluctuations and turbulence in a developing shear layer, and steady-state homogeneous turbulence with a spatially periodic body force.
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    Volume-energy parameters for heat transfer to supercritical fluids (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Reduced Nusselt numbers of supercritical fluids from different sources were grouped by several volume-energy parameters. A modified bulk expansion parameter was introduced based on a comparative analysis of data scatter. Heat transfer experiments on liquefied methane were conducted under near-critical conditions in order to confirm the usefulness of the parameters. It was experimentally revealed that heat transfer characteristics of near-critical methane are similar to those of hydrogen. It was shown that the modified bulk expansion parameter and the Gibbs-energy parameter grouped the heat transfer data of hydrogen, oxygen and methane including the present data on near-critical methane. It was also indicated that the effects of surface roughness on heat transfer were very important in grouping the data of high Reynolds numbers.
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    Unsteady heat transfer and direct comparison to steady-state measurements in a rotor-wake experiment (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Circumferentially local and time-resolved heat transfer measurements were obtained for a circular cylinder in crossflow located downstream of a rotating spoked wheel wake generator in a steady flow tunnel. The unsteady heat transfer effects were obtained by developing an extension of a thin film gauge technique employed to date exclusively in short-duration facilities. The time-average thin film results and conventional steady-state heat transfer measurements were compared. Time-averaged wake-induced stagnation heat transfer enhancement levels above the nowake case were about 10 percent for the four cylinder Reynolds numbers. This enhancement level was nearly independent of bar passing frequency and was related directly to the time integral of the heat transfer spikes observed at the bar passing frequency. It is observed that the wake-induced heat transfer spikes have peak magnitudes averaging 30 to 40 percent above the interwake heat transfer level.
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    Calculation of confined swirling jets (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Computations of a confined coaxial swirling jet are carried out using a standard two-equation (k-epsilon) model and two modifications of this model based on Richardson-number corrections of the length-scale (epsilon) governing equation. To avoid any uncertainty involved in the setting up of inlet boundary conditions, actual measurements are used at the inlet plane of this calculation domain. The results of the numerical investigation indicate that the k-epsilon model is inadequate for the predictions of confined swirling flows. Although marginal improvement of the flow predictions can be achieved by these two corrections, neither can be judged satisfactory.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Communications in Applied Numerical Methods (ISSN 0748-8025); 2; 333-338
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    Initial conditions for parabolic calculation of reacting flows (1986)
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Propulsion and Power (ISSN 0748-4658); 2; 235-240
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    Equilibrium shapes of acoustically levitated drops (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The quantitative determination of the shape of liquid drops levitated in an ultrasonic standing wave has provided experimental data on the radiation pressure-induced deformations of freely suspended liquids. Within the limits of small deviations from the spherical shape and small drop diameter relative to the acoustic wavelength, an existing approximate theory yields a good agreement with experimental evidence. The data were obtained for millimeter and submillimeter drops levitated in air under 1 g, where g is the sea level gravitational acceleration.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Acoustical Society of America, Journal (ISSN 0001-4966); 79; 1335-133
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    Evolution of a curved vortex filament into a vortex ring (1986)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The deformation of a hairpin-shaped vortex filament under self-induction and in the presence of shear is studied numerically using the Biot-Savart law. It is shown that the tip region of an elongated hairpin vortex evolves into a vortex ring and that the presence of mean shear impedes the process. Evolution of a finite-thickness vortex sheet under self-induction is also investigated using the Navier-Stokes equations. The layer evolves into a hairpin vortex which in turn produces a vortex ring of high Reynolds stress content. These results indicate a mechanism for the generation of ring vortices in turbulent shear flows, and a link between the experimental and numerical observation of hairpin vortices and the observation of ring vortices in the outer regions of turbulent boundary layers.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids (ISSN 0031-9171); 29; 955-963
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    Turbulent boundary-layer wall pressure fluctuations downstream of a tandem LEBU (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An initial measurement of turbulent wall pressure fluctuations downstream of tandem large eddy breakup devices (LEBUs) indicates a significant reduction by comparison with the reference case of a flat plate; the average magnitude of the reduction is 12.5 percent. Peak reduction is at 7-8 kHz, and is of the order of the C(f) reduction due to the tandem LEBUs. These data indicate a secondary benefit derivable from LEBUs, in addition to their skin friction reduction effect.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 689-691
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    Three-dimensional low Reynolds number flows with a free surface (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The two-dimensional leveling problem (Degani, Gutfinger, 1976) is extended to three dimensions in the case where the flow Re number is very low and attention is paid to the free surface boundary condition with surface tension effects included. The no-slip boundary condition on the wall is observed. The numerical solution falls back on the Marker and Cell (MAC) method (Harlow and Welch, 1965) with the computation region divided into a finite number of stationary rectangular cells (or boxes in the 3-D case) and fluid flow traverses the cells (or boxes).
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Computational Physics; 24; May 1977
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    Kinetic theory analysis of rarefied gas flow through finite length slots (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: A kinetic-theory analysis is made of the flow of a rarefied monatomic gas through a two-dimensional slot connecting two reservoirs. Numerical solutions are obtained by the moment and discrete-ordinate methods. The former method portrays the transition-regime characteristics well but has limitations in the free-molecule regime. The latter method gives accurate results in the free-molecule and slip regimes and bolsters confidence in the accuracy of the transition-regime results. The numerical solution for the mass flux through the slot agrees well with an approximate analytical solution of the moment equations for length-to-width ratios from 6 to 0.5, pressure ratios from 0.8 to 0.1, and Knudsen numbers from 5 to 0.5.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Physics of Fluids; 20; June 197
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  • 60
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    Effect of compliant wall motion on turbulent boundary layers (1977)
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    Publikationsdatum: 2011-08-17
    Beschreibung: A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 61
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    An implicit-iterative solution of the heat conduction equation with a radiation boundary condition (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: For the problem of predicting one-dimensional heat transfer between conducting and radiating mediums by an implicit finite difference method, four different formulations were used to approximate the surface radiation boundary condition while retaining an implicit formulation for the interior temperature nodes. These formulations are an explicit boundary condition, a linearized boundary condition, an iterative boundary condition, and a semi-iterative boundary method. The results of these methods in predicting surface temperature on the space shuttle orbiter thermal protection system model under a variety of heating rates were compared. The iterative technique caused the surface temperature to be bounded at each step. While the linearized and explicit methods were generally more efficient, the iterative and semi-iterative techniques provided a realistic surface temperature response without requiring step size control techniques.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: International Journal for Numerical Methods in Engineering; 11; 10, 1; 1977
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  • 62
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    Computational fluid dynamics overview (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: The hierarchy of codes; boundary layers and turbulence models; uniqueness and artificial viscosity; efficiency of solution algorithms; data display and analysis; and cost of experimental validation are briefly examined.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Langley Symposium on Aerodynamics, Volume 1; p 5-24
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  • 63
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    Boundary layer transition (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: The boundary layer stability, its active control by sound and surface heating and the effect of curvature are studied numerically and experimentally for subsonic flow. In addition, the experimental and flight test data are correlated using the stability theory for supersonic Mach numbers. Active transition fixing and feedback control of boundary layer by sound interactions are experimentally investigated at low speed over an airfoil. Numerical simulation of active control by surface heating and cooling in air shows that by appropriate phase adjustment a reduction in the level of perturbation can be obtained. This simulation is based on the solution of two-dimensional compressible Navier-Stokes equations for a flat plate. Goertler vortices are studied experimentally on an airfoil in the Low Turbulence Pressure Tunnel (LTPT). The flow pattern was visualized using the sublimating chemical technique and data were obtained using a three component laser velocimeter. The effect of curvature on swept leading-edge stability on a cylinder was numerically studied. The results suggest that transition is dominated by traveling disturbance waves and that the waves with the greatest total amplification has an amplitude ratio of e sup 11. Experimental data from the quiet supersonic tunnel and flight tests are analyzed using linear compressible stability theory.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Langley Symposium on Aerodynamics, Volume 1; p 333-345
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  • 64
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    Numerical simulation of a controlled boundary layer (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: The problem of interest is the boundary layer over a flat plate. The three standard laminar flow control (LFC) techniques are pressure gradient, suction, and heating. The parameters used to describe the amount of control in the context of the boundary layer equations are introduced. The numerical method required to find the mean flow, the linear eigenvalues of the Orr-Sommerfeld equation, and the full, nonlinear, 3-D solution of the Navier-Stokes equations are outlined. A secondary instability exists for the parallel boundary subject to uniform pressure gradient, suction, or heating. Selective control of the spanwise mode reduces the secondary instability in the parallel boundary layer at low Reynolds number.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Langley Symposium on Aerodynamics, Volume 1; p 137-152
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  • 65
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    Radiative and free-convective heat transfer from a finite horizontal plate inside an enclosure (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: An experimental and analytical investigation of heat transfer from a horizontal, thin, square plate inside of an enclosure was carried out. Experimental results were obtained from both the upward-facing and the downward-facing sides of the heated plate. Starting with the integrated momentum and energy equations, approximate solutions were obtained for heat transfer in the laminar and the turbulent regime that correlate well with experimental data. Radiative heat transfer correction was given special attention. Effects of the enclosure-related recirculation of the test fluid, as well as effects of simultaneous heat transfer on both sides of the plate, caused an early transition, and indicated a high level of internal turbulence.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA- Goddard Space Flight Center, Greenbelt, Md. Fourteenth Space Simulation Conference: Testing for a Permanent Presence in Space; p 42-60
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  • 66
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    Turbulent flow field predictions in sharply curved turn around ducts (1986)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: In this investigation, two-dimensional turbulent flow of incompressible Newtonian fluids in sharply curved 180 deg turn around ducts is studied. Results of an approximate numerical flow field analysis utilizing an orthogonal, body-fitted, curvilinear coordinate system are compared to results based on a traditional cylindrical reference frame. Qualitative indication of general streamfield characteristics as well as quantitative benchmarks for the planning of future experimentation are provided. In addition, preliminary results of an augmented kappa-epsilon turbulence model analysis, which explicitly accounts for the effects of streamline curvature and pressure strain in internal turbulent flows, are presented. Specific model difficulties are discussed and comparisons with standard kappa-esilon model predictions are included.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Marshall Space Flight Center Research Reports: 1985 NASA(ASEE Summer Faculty Fellowship Program; 38 p
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    Low density gas dynamic wall boundary conditions (1986)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Low density nozzles or large expansion ratio nozzles used in space experience rarefaction effects near their exit in the form of velocity slip and temperature jump at the walls. In addition, the boundary layers become very thick and there is a very strong viscous/inviscid interaction. For these reasons no existing design technique has been found to accurately predict the nozzle flow properties up to the nozzle exit. The objective of this investigation was to examine the slip boundary conditions and formulate them in a form appropriate for use with a full Navier-Stokes numerical code. The viscous/inviscid interaction would automatically be accounted for by using a compressible Navier-Stokes code. Through examination of the interaction of molecules with solid surfaces, a model for the distribution function of the reflected molecules has been determined and this distribution function has been used to develop a new slip boundary condition that can be shown to yield more realistic surface boundary conditions.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Marshall Space Flight Center Research Reports: 1985 NASA(ASEE Summer Faculty Fellowship Program; 25 p
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    Numerical turbulence modeling (1977)
    In:  CASI
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    Publikationsdatum: 2012-05-19
    Beschreibung: The underlying bases and developments in two techniques of detailed turbulence modeling are described where the flow is treated in the Eulerian sense, and one technique where the Lagrangian motions of vortices are followed. First, a technique is described for solving the single-point statistically averaged conservation equations. The Reynolds stresses that appear in these equations are evaluated by solving supplemental differential equations which contain terms that are modeled. A sequence of increasingly complex, but also increasingly general, modeling equations is described and computations based on these equations are compared with experimental data. The hierarchy of models described terminates with equations for the individual components of the Reynolds stress tensor. The second Eulerian technique approach to turbulence modeling is the direct numerical simulation of turbulent fields. In this approach, all three dimensional eddies between a predetermined range of sizes are computed in time within a specified volume of flow. Present day computers require a tradeoff between the size of the volume that can be considered and the degree of resolution of the turbulent eddies. Techniques of modeling the smallest eddies are described that permit enlarging the volume, or Reynolds number, that can be considered.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AGARD Computational Fluid Dyn.; 37 p
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    Prediction of outer layer mixing lengths in turbulent boundary layers (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: Predictions of mixing length by Pletcher's (1976) method (using a two-layer eddy viscosity model for a turbulent boundary layer at low Reynolds numbers) are compared to some values derived from turbulent boundary-layer profiles by other authors. The model is incorporated into a finite-difference scheme, to accurately predict low Reynolds number skin friction in supersonic flow.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal; 15; Apr. 197
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    Hot-wire anemometry in transonic flow (1977)
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    Publikationsdatum: 2011-08-17
    Beschreibung: The use of hot-wire anemometry for obtaining fluctuating data in transonic flows has been evaluated. From hot-wire heat loss correlations based on previous transonic data, the sensitivity coefficients for velocity, density, and total temperature fluctuations have been calculated for a wide range of test conditions and sensor parameters. For sensor Reynolds number greater than 20 and high sensor overheat ratios, the velocity sensitivity remains independent of Mach number and equal to the density sensitivity. These conditions were verified by comparisons of predicted sensitivities with those from recent direct calibrations in transonic flows. Based on these results, techniques are presented to obtain meaningful measurements of fluctuating velocity, density, and Reynolds shear stress using hot-wire and hot-film anemometers. Example of these measurements are presented for two transonic boundary layers.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal; 15; Mar. 197
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  • 71
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    A block iterative finite element algorithm for numerical solution of the steady-state, compressible Navier-Stokes equations (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: An iterative method for numerically solving the time independent Navier-Stokes equations for viscous compressible flows is presented. The method is based upon partial application of the Gauss-Seidel principle in block form to the systems of the nonlinear algebraic equations which arise in construction of finite element (Galerkin) models approximating solutions of fluid dynamic problems. The continuous cubic element on triangles is employed for function approximation. Computational results for a free shear flow at Re = 1000 indicate significant achievement of economy in iterative convergence rate over finite element and finite difference models which employ the customary time dependent equations and symptotic time marching procedure to steady solution. Numerical results are in excellent agreement with those obtained for the same test problem employing time marching finite element and finite difference solution techniques.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: International Journal for Numerical Methods in Engineering; 11; 12, 1; 1977
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    Condensation heat transfer in rotating heat pipes in the presence of a non-condensable gas (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: An analysis of condensation problems in rotating heat pipes containing vapors with different concentrations of non-condensable gases is given. In situations such as this, temperature and concentration gradients are set up in the vapor-gas mixture. There is a transport of mass due to temperature gradients accompanied by an energy transport phenomena due to a concentration gradient. A Nusselt type analysis is not suited to this type of problem; however, a boundary layer type approach has successfully been used to analyze stationary condensation systems with non-condensable gases present. The present boundary layer analysis is presented for condensation processes on the inside of a rotating heat pipe in the presence of non-condensable gases.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Revue Roumaine des Sciences Techniques; vol. 22
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    Revised international representations for the viscosity of water and steam and new representations for the surface tension of water (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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    Boundary layer measurements using hot-film sensors (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Measurements in the aerodynamic boundary layer using heat transfer, hot-film sensors are receiving a significant amount of effort at the Langley Research Center. A description of the basic sensor, the signal conditioning employed, and several manifestations of the sensor are given. Results of a flow reversal sensor development are presented, and future work areas are outlined.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Laminar Flow Aircraft Certification; p 141-153
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    Boundary layer flow visualization for flight testing (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Flow visualization is used extensively in flight testing to determine aerodynamic characteristics such as surface flow direction and boundary layer state. Several visualization techniques are available to the aerodynamicist. Two of the most popular are oil flows and sublimating chemicals. Oil is used to visualize boundary layer transition, shock wave location, regions of separated flow, and surface flow direction. Boundary layer transition can also be visualized with sublimating chemicals. A summary of these two techniques is discussed, and the use of sublimating chemicals is examined in some detail. The different modes of boundary layer transition are characterized by different patterns in the sublimating chemical coating. The discussion includes interpretation of these chemical patterns and the temperature and velocity operating limitations of the chemical substances. Information for selection of appropriate chemicals for a desired set of flight conditions is provided.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA, Langley Research Center, Laminar Flow Aircraft Certification; p 129-140
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    Laminar flow integration: Flight tests status and plans (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Under the Aircraft Energy Efficiency - Laminar Flow Control Program, there are currently three flight test programs under way to address critical issues concerning laminar flow technology application to commercial transports. The Leading-Edge Flight Test (LEFT) with a JetStar aircraft is a cooperative effort with the Ames/Dryden Flight Research Facility to provide operational experience with candidate leading-edge systems representative of those that might be used on a future transport. In the Variable Sweep Transition Flight Experiment (VSTFE), also a cooperative effort between Langley and Ames/Dryden, basic transition data on an F-14 wing with variable sweep will be obtained to provide a data base for laminar flow wing design. Finally, under contract to the Boeing Company, the acoustic environment on the wing of a 757 aircraft will be measured and the influence of engine noise on laminar flow determined with a natural laminar flow glove on the wing. The status and plans for these programs are reported.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Langley Symposium on Aerodynamics, Volume 1; p 485-518
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    Separated flow (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: A brief overview of flow separation phenomena is provided. Langley has many active research programs in flow separation related areas. Three cases are presented which describe specific examples of flow separation research. In each example, a description of the fundamental fluid physics and the complexity of the flow field is presented along with a method of either reducing or controlling the extent of separation. The following examples are discussed: flow over a smooth surface with an adverse pressure gradient; flow over a surface with a geometric discontinuity; and flow with shock-boundary layer interactions. These results will show that improvements are being made in the understanding of flow separation and its control.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Langley Symposium on Aerodynamics, Volume 1; p 361-374
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    Applications of heat pipes to cool PWBS and hybrid microcircuits (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Some of the advanced thermal management techniques used to reduce operating junction temperature under extreme environmental temperature conditions are discussed. Heat pipes in actual electronic packaging applications, and those under development, are discussed. Performance characteristics of heat pipes are given, and examples are described of how thermal problems in electronic packaging are solved through the use of heat pipes.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA- Goddard Space Flight Center, Greenbelt, Md. Fourteenth Space Simulation Conference: Testing for a Permanent Presence in Space; p 331-340
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    Explicit finite-volume time-marching calculations of total temperature distributions in turbulent flow (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: A method was developed which calculates two-dimensional, transonic, viscous flow in ducts. The finite volume, time-marching formulation is used to obtain steady flow solutions of the Reynolds-averaged form of the Navier-Stokes equations. The entire calculation is performed in the physical domain. This paper investigates the introduction of a new formulation of the energy equation which gives improved transient behavior as the calculation converges. The effect of variable Prandtl number on the temperature distribution through the boundary layer is also investigated. A turbulent boundary layer in an adverse pressure gradient (M = 0.55) is used to demonstrate the improved transient temperature distribution obtained when the new formulation of the energy equation is used. A flat plate turbulent boundary layer with a supersonic free-stream Mach number of 2.8 is used to investigate the effect of Prandtl number on the distribution of properties through the boundary layer. The computed total temperature distribution and recovery factor agree well with the measurements when a variable Prandtl number is used through the boundary layer.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Thermodynamic Evaluation of Transonic Compressor Rotors Using the Finite Volume Approach; p 71-82
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    An explicit finite-volume time-marching procedure for turbulent flow calculations (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: A method was developed which calculates two-dimensional, transonic, viscous flow in ducts. The finite-volume, time-marching formulation is used to obtain steady flow solutions of the Reynolds-averaged form of the Navier-Stokes equations. The entire calculation is performed in the physical domain. Control volumes are chosen so that smoothing of flow properties, typically required for stability, is not required. Different time steps are used in the different governing equations. A new pressure interpolation scheme is introduced which improves the shock capturing ability of the method. A multi-volume method for pressure changes in the boundary layer allows calculations which use very long and thin control volumes (length/height - 1000). The method is compared with two test cases. Essentially incompressible turbulent boundary layer flow in an adverse pressure gradient is calculated and the computed distributions of mean velocity and shear are in good agreement with the measurements. Transonic viscous flow in a converging diverging nozzle is calculated; the Mach number upstream of the shock is approximately 1.25. The agreement between the calculated and measured shock strength and total pressure losses is good.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Thermodynamic Evaluation of Transonic Compressor Rotors Using the Finite Volume Approach; p 59-70
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    Development of an explicit time marching procedure for laminar and turbulent flow (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: A finite-volume based, time-marching method for turbulent and laminar flows is described. Extensions to the computational procedure to allow the handling of shock induced separation and large regions of strong backflow are emphasized. Two test cases are considered, the United Technologies Research Center (UTRC) separated and reattached turbulent boundary layer and the strong shock case in the McDonnell Douglas Research Lab (MDRL) transonic diffuser G. The extended method worked well on the UTRC flow with a boundary layer blockage of 58% and a maximum backflow velocity of 37% of the local maximum free-stream velocity. It also worked well on the MDRL diffuser with a shock Mach number of 1.353 and a maximum backflow velocity of -71.7 m/s. A Mach number dependent interpolation formula for effective pressure was developed for use in density-update time-marching methods.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Thermodynamic Evaluation of Transonic Compressor Rotors Using the Finite Volume Approach; p 4-46
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    Sharply curved turn around duct flow predictions using spectral partitioning of the turbulent kinetic energy and a pressure modified wall law (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Computational predictions of turbulent flow in sharply curved 180 degree turn around ducts are presented. The CNS2D computer code is used to solve the equations of motion for two-dimensional incompressible flows transformed to a nonorthogonal body-fitted coordinate system. This procedure incorporates the pressure velocity correction algorithm SIMPLE-C to iteratively solve a discretized form of the transformed equations. A multiple scale turbulence model based on simplified spectral partitioning is employed to obtain closure. Flow field predictions utilizing the multiple scale model are compared to features predicted by the traditional single scale k-epsilon model. Tuning parameter sensitivities of the multiple scale model applied to turn around duct flows are also determined. In addition, a wall function approach based on a wall law suitable for incompressible turbulent boundary layers under strong adverse pressure gradients is tested. Turn around duct flow characteristics utilizing this modified wall law are presented and compared to results based on a standard wall treatment.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Marshall Space Flight Center Research Reports: 1986 NASA(ASEE Summer Faculty Fellowship Program; 37 p
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  • 83
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    Computation of nozzle flow fields using the PARC2D Navier-Stokes code (1986)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: Supersonic nozzles which operate at low Reynolds numbers and have large expansion ratios have very thick boundary layers at their exit. This leads to a very strong viscous/inviscid interaction upon the flow within the nozzle and the traditional nozzle design techniques which correct the inviscid core with a boundary layer displacement do not accurately predict the nozzle exit conditions. A full Navier-Stokes code (PARC2D) was used to compute the nozzle flow field. Grids were generated using the interactive grid generator code TBGG. All computations were made on the NASA MSFC CRAY X-MP computer. Comparison was made between the computations and in-house wall pressure measurements for CO2 flow through a conical nozzle having an area ratio of 40. Satisfactory agreement existed between the computations and measurements for a stagnation pressure of 29.4 psia and stagnation temperature of 1060 R. However, agreement did not exist at a stagnation pressure of 7.4 psia. Several reasons for the lack of agreement are possible. The computational code assumed a constant gas gamma whereas gamma for CO2 varied from 1.22 in the plenum chamber to 1.38 at the nozzle exit. Finally, it is possible that condensation occurred during the expansion at the lower stagnation pressure.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Marshall Space Flight Center Research Reports: 1986 NASA(ASEE Summer Faculty Fellowship Program; 25 p
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  • 84
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    Advanced thermal energy management: A thermal test bed and heat pipe simulation (1986)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA. Marshall Space Flight Center Research Reports: 1986 NASA(ASEE Summer Faculty Fellowship Program; 25 p
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  • 85
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    Transient modeling of the thermohydraulic behavior of high temperature heat pipes for space reactor applications (1986)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: Many proposed space reactor designs employ heat pipes as a means of conveying heat. Previous researchers have been concerned with steady state operation, but the transient operation is of interest in space reactor applications due to the necessity of remote startup and shutdown. A model is being developed to study the dynamic behavior of high temperature heat pipes during startup, shutdown and normal operation under space environments. Model development and preliminary results for a hypothetical design of the system are presented.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA- Goddard Space Flight Center, Greenbelt, Md. Fourteenth Space Simulation Conference: Testing for a Permanent Presence in Space; p 313-330
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  • 86
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    Experiments and modeling of dilution jet flow fields (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Experimental and analytical results of the mixing of single, double, and opposed rows of jets with an isothermal or variable-temperature main stream in a straight duct are presented. This study was performed to investigate flow and geometric variations typical of the complex, three-dimensional flow field in the dilution zone of gas-turbine-engine combustion chambers. The principal results, shown experimentally and analytically, were the following: (1) variations in orifice size and spacing can have a significant effect on the temperature profiles; (2) similar distributions can be obtained, independent of orifice diameter, if momentum-flux ratio and orifice spacing are coupled; (3) a first-order approximation of the mixing of jets with a variable-temperature main stream can be obtained by superimposing the main-stream and jets-in-an-isothermal-crossflow profiles; (4) the penetration of jets issuing mixing is slower and is asymmetric with respect to the jet centerplanes, which shift laterally with increasing downstream distance; (5) double rows of jets give temperature distributions similar to those from a single row of equally spaced, equal-area circular holes; (6) for opposed rows of jets, with the orifice centerlines in line, the optimum ratio of orifice spacing to duct height is one-half the optimum value for single-side injection at the same momentum-flux ratiol and (7) for opposed rows of jets, with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is twice the optimum value for single-side injection at the same momentum-flux ratio.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA-Chinese Aeronautical Establishment (CAE) Symposium; p 149-174
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  • 87
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    Two-phase flow (1986)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: An experimental program to characterize the spray from candidate nozzles for icing-cloud simulation is discussed. One canidate nozzle, which is currently used for icing research, has been characterized for flow and drop size. The median-volume diameter (MVD) from this air-assist nozzle is compared with correlations in the literature. The new experimental spray facility is discussed, and the drop-size instruments are discussed in detail. Since there is no absolute standard for drop-size measurements and there are other limitations, such as drop -size range and velocity range, several instruments are used and results are compared. A two-phase model was developed at Pennsylvania State University. The model uses the k-epsilon model of turbulence in the continous phase. Three methods for treating the discrete phase are used: (1) a locally homogeneous flow (LHF) model, (2) a deterministic separated flow (DSF) model, and (3) a stochastic separated flow (SSF) model. In the LHF model both phases have the same velocity and temperature at each point. The DSF model provides interphase transport but ignores the effects of turbulent fluctuations. In the SSF model the drops interact with turbulent eddies whose properties are determined by the k-epsilon turbulence model. The two-phase flow model has been extended to include the effects of evaporation and combustion.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA-Chinese Aeronautical Establishment (CAE) Symposium; p 63-87
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  • 88
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    Modeling turbulent, reacting flow (1986)
    In:  CASI
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    Publikationsdatum: 2013-08-31
    Beschreibung: Several of the approximations or models involved in the development of a numerical combustor flow code are examined. In the first section, the importance of numerical accuracy is illustrated, and the impact that improved-accuracy schemes have on slowing convergence is demonstrated. Solution algorithms that can speed convergence are discussed and some performance features of these algorithms are illustrated. A sample calculation displaying the importance of boundary conditions on a three-dimensional numerical prediction is presented. The inaccuracy of a current turbulence model in highly turbulent (nonequilibrium) regions is described. Finally, the surprisingly good performance of a six-flux model in describing radiation heat transfer is displayed. In all the areas examined, continued research is still needed, but valuable engineering tools are available today.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA-Chinese Aeronautical Establishment (CAE) Symposium; p 31-46
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  • 89
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    Experimental and analytical investigation of the variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer (1986)
    In:  CASI
    Details
    Publikationsdatum: 2013-08-31
    Beschreibung: The variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer was measured by laser light-scattering technology. An analytical model was developed to predict the variation of spray characteristics along the radial distance. A comparison of the predicted and experimental data showed excellent agreement. Therefore, the spray model proposed, although relatively simple, is correct and can be used, with some expansion and modification of the prepared model, to predict more complicated spray systems.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: NASA- Lewis Research Center NASA-Chinese Aeronautical Establishment (CAE) Symposium; p 47-62
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  • 90
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    Using the boundary-layer equations in three-dimensional viscous flow simulation (1986)
    In:  CASI
    Details
    Publikationsdatum: 2012-05-17
    Beschreibung: A simple and computationally efficient algorithm for solving the unsteady three dimensional boundary layer equations in a time accurate or relaxation mode is presented. The algorithm is used to compute the separated flow over a 6:1 ellipsoid at angle of attack and the transonic flow over a finite wing with shock induced separation. These results are compared to available experimental data. A method of using the boundary layer algorithm to accelerate a Navier-Stokes computation is also presented. Example computations indicate that a boundary layer algorithm can be used to improve both the accuracy and efficiency of a Navier-Stokes algorithm.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AGARD Applications of Computational Fluid Dynamics in Aeronautics; 12 p
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  • 91
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    Monte Carlo turbulence simulation (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The paper describes turbulence simulation experiments based on the principles of control system theory, that is, the construction of a system characterized by a system function such that upon exciting the system with prescribed noise processes the output of the system is a realization of a random processing the desired statistical attributes of turbulence. An experimental autocorrelation of Jimsphere measurements of wind velocity was approximated to simulate turbulent wind. From the approximate autocorrelation function, the required system function is obtained, and a discrete time system is designed. Another method of simulation is to solve the convolution integral by filter techniques. Other methods include discrete Fourier simulation and self-similar simulation.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 92
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    Turbulence processes and simple closure schemes (1977)
    In:  Other Sources
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    Publikationsdatum: 2011-08-17
    Beschreibung: The problem of closure in turbulence in the case of two-point correlations resides in the existence of two unknowns E and W, the energy spectrum function and the transfer function, respectively, in the spectrum equation. In the case of weak turbulence, W is negligible. In case of higher correlations, closure can be effective by neglecting the inertia term in the highest order term used. Specifying a certain number of spectra at an initial time is also a way of getting around the closure problem. A simple case of turbulent shear flow is then considered, where two-point correlation equations are used and the velocity is broken into mean and fluctuating components. This yields a differential equation for the energy spectrum, the three terms of which are the energy spectrum, production term and dissipation term. They are plotted for a particular time. Similar analyses and comparisons with experiment are made for pipe and boundary layer flows.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 93
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    Modeling dilution of jet flowfields (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Propulsion and Power (ISSN 0748-4658); 2; 4-10
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  • 94
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    Wall temperature control of low-speed body drag (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The use of thermal means to control drag under turbulent boundary layer conditions is examined. Numerical calculations are presented for both skin friction and (unseparated) pressure drag for turbulent boundary-layer flows over a fuselage-like body with wall heat transfer. In addition, thermal control of separation on a bluff body is investigated. It is shown that a total drag reduction of up to 20 percent can be achieved for wall heating with a wall-to-total-freestream temperature ratio of 2. For streamlined slender bodies, partial wall heating of the forebody can produce almost the same order of total drag reduction as the full body heating case. For bluff bodies, the separation delay from partial wall cooling of the afterbody is approximately the same as for the fully cooled body.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Aircraft (ISSN 0021-8669); 23; 93
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  • 95
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    Monte Carlo turbulence simulation using rational approximations to von Karman spectra (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Turbulence simulation is computationally much simpler using rational spectra, but turbulence falls off as f exp -5/3 in frequency ranges of interest to aircraft response and as predicted by von Karman's model. Rational approximations to von Karman spectra should satisfy three requirements: (1) the rational spectra should provide a good approximation to the von Karman spectra in the frequency range of interest; (2) for stability, the resulting rational transfer function should have all its poles in the left half-plane; and (3) at high frequencies, the rational spectra must fall off as an integer power of frequency, and since the -2 power is closest to the -5/3 power, the rational approximation should roll off as the -2 power at high frequencies. Rational approximations to von Karman spectra that satisfy these three criteria are presented, along with spectra from simulated turbulence. Agreement between the spectra of the simulated turbulence and von Karman spectra is excellent.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 62-66
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  • 96
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    Implicit conservative schemes for the Euler equations (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: AIAA Journal (ISSN 0001-1452); 24; 215-223
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  • 97
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    The structure of the vorticity field in turbulent channel flow. II - Study of ensemble-averaged fields (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Several conditional sampling techniques are applied to a data base generated by large-eddy simulation of turbulent channel flow. It is shown that the bursting process is associated with well-organized horseshoe vortices inclined at about 45 deg to the wall. These vortical structures are identified by examining the vortex lines of three-dimensional, ensemble averaged vorticity fields. Two distinct horseshoe-shaped vortices corresponding to the sweep and ejection events are detected. These vortices are associated with high Reynolds shear stress and hence make a significant contribution to turbulent energy production. The dependency of the ensemble averaged vortical structures on the detection criteria, and the question of whether this ensemble-averaged structure is an artifact of the ensemble averaging process are examined. The ensemble-averaged pattern of these vortical structures that emerge from the analysis could provide the basis for a hypothetical model of the organized structures of wall-bounded shear flows.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Journal of Fluid Mechanics (ISSN 0022-1120); 162; 339-363
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  • 98
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    Experimental verification of corrosive vapor deposition rate theory in high velocity burner rigs (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The ability to predict deposition rates is required to facilitate modelling of high temperature corrosion by fused salt condensates in turbine engines. A corrosive salt vapor deposition theory based on multicomponent chemically frozen boundary layers (CFBL) has been successfully verified by high velocity burner rig experiments. The experiments involved internally air-impingement cooled, both rotating full and stationary segmented cylindrical collectors located in the crossflow of sodium-seeded combustion gases. Excellent agreement is found between the CFBL theory and the experimental measurements for both the absolute amounts of Na2SO4 deposition rates and the behavior of deposition rate with respect to collector temperature, mass flowrate (velocity) and Na concentration.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
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  • 99
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    Patched-grid calculations with the Euler and Navier-Stokes equations: Theory and application (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The Rai (1984,85) patch-boundary scheme for the Euler equations is described. The integration methods used to update the interior grid points are are discussed. Stability of patch-boundary schemes and the use of these schemes in Navier-Stokes calculations are mentioned. Results for inviscid, supersonic flow over a cylinder, blast wave diffraction by ramp, and the motion of a vortex in a freestream are presented. These test cases demonstrate the quality of solutions possible with the scheme.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Von Karman Inst. for Fluid Dynamics Computational Fluid Dynamics, Volume 1; 102 p
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  • 100
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    Efficient solution methods for the Navier-Stokes equations (1986)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Implicit finite difference schemes for solving two-dimensional and three-dimensional Euler and thin layer Navier-Stokes equations are addressed. The methods are demonstrated in fully vectorized codes for a Cray type architecture. The Beam and Warming implicit approximate factorization algorithm in generalized coordinates is used. The methods are either time accurate or accelerated non-time accurate steady state schemes. Acceleration and efficiency modifications such as matrix reduction, diagonalization, and flux split schemes are presented. Two dimensional inviscid and viscous calculations (e.g., airfoils with a deflected spoiler, circulation control airfoils, and unsteady buffeting) and of three dimensional viscous elliptical bodies, exhausting boattails, and generic oblique wing computations are discussed.
    Schlagwort(e): FLUID MECHANICS AND HEAT TRANSFER
    Materialart: Von Karman Inst. for Fluid Dynamics Numerical Techniques for Viscous Flow Calculations in Turbomachinery Bladings; 104 p
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