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NONITERATIVE PARABOLIC GRID GENERATION FOR PARABOLIZED EQUATIONS

AIAA JOURNAL 1987年第4期25卷 542-549页

作者： HODGE, JK LEONE, SA MCCARTY, RL Air Force Institute of Technology Wright-Patterson Air Force Base Ohio

Three-dimensional generalized curvilinear grids are generated for Cartesian, cylindrical, and spherical shaped bodies using parabolic partial differential equations. Elliptic grid equations are parabolized in an axial direction consistent with the Parabolized Navier Stokes (PNS) equations or the boundary-layer equations. The parabolized grid equations are solved in a noniterative fashion by marching in two directions. Any limitations of parabolic grid generation are investigated on convex and concave corners. Even though body surfaces are not smooth, the grid between axial stations is smoothed. Highly stretched and optimized grids for high Reynold's number are accurately and efficiently generated for the first time using parabolic grid equations with a difference approximation based on exponentials. The grid can also be adapted easily based on a flow solution at the previous axial station using this approach. © 1987 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Boundary Layer Equations Poisson's Equation Turbulent Flow Velocity Profiles Finite Difference Approximation Cartesian Coordinate System solution algorithm Iterative solution Computer Memory Flow Equations

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RAYLEIGH MEASUREMENTS OF SPECIES CONCENTRATION IN A COMPLEX TURBULENT-FLOW

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AIAA JOURNAL 1987年第8期25卷 1142-1144页

作者： DEGROOT, WA LATHAM, R JAGODA, JI STRAHLE, WC Georgia Institute of Technology Atlanta Georgia

Local bleed gas concentrations were measured for an axial inlet velocity of 70 m/s and a bleed gas velocity of 0. 5 m/s, which corresponds to a typical gasification rate of the fuel in the solid-fueled ramjets. None of the pdf's obtained were bimodal, indicating that the residence times in the recirculation zone were long enough for molecular mixing to prevent any pockets of pure bleed gas to be observed above 0. 1 step height above the bleed plate.

关键词： Two Dimensional Flow Mixing Length Model solution algorithm Exploratory Testing Data Acquisition Rayleigh Scattering Mie Scattering Shear Layers Ramjet Turbulence Intensity

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APPLICATION OF A VARIATIONAL METHOD FOR GENERATING ADAPTIVE GRIDS

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AIAA JOURNAL 1986年第3期24卷 404-410页

作者： KREIS, RI THAMES, FC HASSAN, HA NASA LANGLEY RES CTRDIV TRANSON AERODYNAMTHEORET AERODYNAM BRANCHHAMPTONVA 23665

Application of variational methods for generating adaptive grids is not as straightforward as one is led to believe. Proper scaling, suitable weight functions, and appropriate clustering on boundaries must be employed to obtain a satisfactory grid. This work, which is based on the framework developed by Brackbill and Salt/man, provides simple methods for determining scaling and investigates possible options for selecting the weight function and clustering points on the boundaries. The concepts developed here are applied to 2 two-dimensional problems: a model problem based on Burger's equation containing two length scales and transonic flow past airfoils using the Euler equations. © 1986 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Euler Equations Transonic Flow NACA 0012 Airfoil Flow solution algorithm Gasdynamics

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CALCULATION OF AXISYMMETRICAL, TURBULENT, CONFINED DIFFUSION FLAMES

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AIAA JOURNAL 1986年第3期24卷 462-469页

作者： VANKA, SP Argonne National Laboratory Argonne Illinois

A solution algorithm based on a fully coupled solution of the time-averaged Navier-Stokes equations is developed for the calculation of turbulent reacting flows. The governing elliptic partial differential equations are discretized by finite differences and the nonlinear algebraic equations are solved by a block-implicit algorithm employing Newton’s method and sparse matrix techniques. Calculations have been made of a confined turbulent diffusion flame. Turbulence is represented by the k - ∈ model and chemical reaction is assumed to occur in one step at an infinite rate, controlled by the mixing of fuel and oxidant streams. It is demonstrated that the strategy of a coupled solution is rapidly convergent even in the presence of significant density variations. Calculations with finite difference grids as large as 80 × 100 have been made successfully in modest computer time and with modest storage. The calculations are compared with experimental data. © 1986 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Fuel Air Ratio Continuity Equation Chemically Reacting Flow Aspect Ratio Kinetic Energy solution algorithm Numerical Stability Shear Layers Gaseous Fuel Turbulence Models

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TRILATERATION AND EXTENSION TO GLOBAL POSITIONING SYSTEM NAVIGATION

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1986年第6期9卷 715-717页

作者： FANG, BT The Analytic Sciences Corporation McLean Virginia

Trilateration is the determination of a navigation position based on simultaneous ranging from three trackers. It is a problem of simple geometry and a solution algorithm is given by Escobal. The Escobal algorithm is unnecessarily complex. By referencing the navigation position to the plane defined by the three trackers, simple explicit solutions are obtained in this Note. It is shown that the method can be easily extended to Global Positioning Systems (GPS) navigation, which requires the determination of time in addition to the position.

关键词： GPS Earth Iterative solution solution algorithm Earth Satellites Doppler Shift

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ARTIFICIAL DISSIPATION MODELS FOR THE EULER EQUATIONS

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AIAA JOURNAL 1986年第12期24卷 1931-1940页

作者： PULLIAM, TH NASA Ames Research Center Moffett Field California

Various artificial dissipation models that are used with central difference algorithms for the Euler equations are analyzed for their effect on accuracy, stability, and convergence rates. In particular, linear and nonlinear models are investigated using an implicit approximate factorization code (ARC2D) for transonic airfoils. Fully implicit application of the dissipation models is shown to improve robustness and convergence rates. The treatment of dissipation models at boundaries will be examined. It will be shown that accurate, error free solutions with sharp shocks can be obtained using a central difference algorithm coupled with an appropriate nonlinear artificial dissipation model. © 1986 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Rankine Hugoniot Relation Total Variation Diminishing Supersonic Flow Viscosity NACA 0012 Navier Stokes Equations solution algorithm Angle of Attack Numerical algorithms Specific Heat

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3-DIMENSIONAL INVISCID FLOW IN MIXERS .1. MIXER ANALYSIS USING A CARTESIAN GRID

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JOURNAL OF PROPULSION AND POWER 1986年第3期2卷 275-281页

作者： BARBER, TJ MULLER, GL RAMSAY, SM MURMAN, EM PRATT & WHITNEY AIRCRAFT E HARTFORDCT 06108 MIT AERONAUT & ASTRONAUTCAMBRIDGEMA 02139

A three-dimensional potential flow analysis has been formulated and applied to the inviscid flow over a turbofan forced mixer. In Part I, a method using a novel small disturbance formulation is presented which analytically uncouples the circumferential flow from the radial and axial flow problem, thereby reducing the analysis to the solution of a series of axisymmetric problems. These equations are discretized using a flux volume formulation along a Cartesian grid. The method extends earlier applications of the Cartesian method to complex cambered multicomponent geometries. Calculations are presented for a symmetric mixer in a planar duct. Good agreement is obtained with a small disturbance singularity superposition analysis. In Part II, the method is extended to treat flows with different energy levels and applied to experimentally tested turbofan forced mixer geometries. © 1986 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： One Dimensional Flow Pressure Coefficient Vortex Sheet Compressibility Static Pressure Mach Numbers Mass Flux Turbofan solution algorithm Gas Turbine Engines

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IMPLICIT CONSERVATIVE SCHEMES FOR THE EULER EQUATIONS

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AIAA JOURNAL 1986年第2期24卷 215-223页

作者： WORNOM, SF HAFEZ, MM UNIV CALIF DAVIS DEPT MECH ENGNDAVISCA 95616

A new approach to a characteristic modeling scheme is presented that does not require the governing equations to be written in characteristic variables or the flux terms to be split into positive and negative parts. The method is based on the observation that, for certain finite volume schemes, the upwind influence can be accounted for through the conditions applied at the boundaries of individual cells instead of flux differencing. The method is developed and applied to the one-dimensional nozzle flow equations for subsonic, transonic, and supersonic flows and is then extended to two dimensions using an approximate factorization. For the problem of a shock wave reflecting from a flat plate, the present solution algorithm reduces the computational work per time step by 40% of that required by standard, central difference, implicit, calculations. © 1986 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Continuity Equation One Dimensional Flow solution algorithm Mach Cones Finite Volume Scheme Aerodynamics Computational Fluid Dynamics Central Processing Unit Implicit Methods Conservation of Mass

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APPROXIMATE FACTORIZATION algorithm FOR 3-DIMENSIONAL TRANSONIC NACELLE INLET FLOWFIELD COMPUTATIONS

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JOURNAL OF PROPULSION AND POWER 1985年第1期1卷 58-64页

作者： VADYAK, J ATTA, EH Lockheed-Georgia Company Marietta Georgia

A highly efficient computer analysis has been developed for predicting transonic nacelle/inlet flowfields. This algorithm can compute the three-dimensional transonic flowfield about axisymmetric or asymmetric nacelle/inlet configurations at zero or nonzero incidence. The flowfield is determined by solving the fullpotential equation in conservative form on a body-fitted curvilinear computational mesh. The difference equations are solved using the AF2 approximate factorization scheme. The effects of boundary-layer viscous entrainment are approximated in the inviscid algorithm by applying a surface transpiration velocity determined from the calculated boundary-layer growth. Computed results and correlations with existing methods and experiment are presented to illustrate application of the analysis. © 1985 American Institute of Aeronautics and Astronautics, Inc.

关键词： Nacelles Boundary Layer Analysis Freestream Mach Number Supercritical Flow Angle of Attack Pressure Coefficient Viscosity solution algorithm Numerical Stability Computing

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CALCULATION OF UNSTEADY FAN ROTOR RESPONSE CAUSED BY DOWNSTREAM FLOW DISTORTIONS

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JOURNAL OF PROPULSION AND POWER 1985年第6期1卷 464-469页

作者： OBRIEN, WF NG, WF RICHARDSON, SM Virginia Polytechnic Institute and State University Blacksburg Virginia

A method for the calculation of the circumferentially-varying flow field in an axial-flow fan with downstream stator guide vanes and casing support struts is described. A time-marching solution for the rotor is coupled to a potential flow solution for downstream flow in the vane and strut regions. The influence of strut design parameters is studied employing the method. It is found that strut thickness, circumferential spacing, and sepation distance from the rotor are primary variables determining unsteady rotor response. The stator row is shown to reduce the effective rotor-strut spacing, contributing to increased rotor-strut flow interaction. Good agreement is obtained between predicted and measured on-rotor pressure fluctuations from a test rig. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Incompressible Flow Pressure Coefficient Angle of Attack Rotor Blades Euler Equations Fluid Mechanics Mach Number solution algorithm Turbofan Engines Perfect Gas

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