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GENERAL 3-DIMENSIONAL VISCOUS PRIMARY SECONDARY FLOW-ANALYSIS

AIAA JOURNAL 1991年第3期29卷 361-370页

作者： GOVINDAN, TR BRILEY, WR MCDONALD, H Scientific Research Associates Inc. Glastonbury Connecticut 06033

Generalized primary/secondary flow equations are derived as an approximation to the Navier-Stokes equations for three-dimensional viscous flows with a dominant flow direction. The primary/secondary flow equations are well posed for solution by spatial marching and can be solved one to two orders of magnitude faster than the Navier-Stokes equations. A key element in the approximations, which is a distinguishing feature of the present approach, is that accuracy is related to curvature terms obtained from a local primary flow direction rather than the coordinate system used to describe geometry of the flowfield. Potential flow streamlines for the flow geometry under consideration are a suitable choice for the primary flow direction. A sequentially decoupled implicit algorithm has been developed that exploits the form of the primary/secondary flow equations to obtain decoupled subsets of equations through choices for dependent variables, the sequence of equations, and the linearization scheme. Each of the equation subsets is solved by efficient and appropriate implicit numerical procedures. Computed solutions for flow in 90-deg bends agree very well with experimental data and Navier-Stokes solutions. The combined efficiency and accuracy of the approximate equations and solution algorithm make this approach attractive for problems in which a suitable primary flow direction can be identified.

关键词： Three Dimensional Turbulent Flow Navier Stokes Equations Mach Numbers solution algorithm No Slip Condition Continuity Equation Vortices Prandtl Number Velocity Profiles Mass Flux

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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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UNSTEADY EULER algorithm WITH UNSTRUCTURED DYNAMIC MESH FOR COMPLEX-AIRCRAFT AERODYNAMIC ANALYSIS

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AIAA JOURNAL 1991年第3期29卷 327-333页

作者： BATINA, JT NASA Langley Research Center Hampton Virginia 23665

An Euler solution algorithm is presented for unsteady aerodynamic analysis of complex-aircraft configurations. The flow solver involves a multistage Runge-Kutta time-stepping scheme that uses a finite-volume spatial discretization on an unstructured grid made up of tetrahedra. A significant contribution of the research is the development and implementation of a moving mesh algorithm that is employed for problems involving static or dynamic deformation of the aircraft. The mesh algorithm is a general procedure that can treat realistic motions and deformations of complex-aircraft configurations. Steady and unsteady results are presented for a supersonic fighter configuration to demonstrate applications of the Euler solver and dynamic mesh algorithm. The unsteady flow results were obtained for the aircraft oscillating harmonically in a complete-vehicle bending mode. Effects of angle of attack and reduced frequency on instantaneous pressures and force responses were investigated. The paper presents descriptions of the Euler solver and dynamic mesh algorithm along with results that assess the capability.

关键词： Boeing 747 Lift Coefficient Aircraft Configurations Unstructured Grid Flow Conditions Unsteady Aerodynamic Analysis solution algorithm Aerodynamic Simulation Euler Equations Canard

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Numerical optimization of the suction distribution for laminar flow control

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AIAA JOURNAL 2000年第2期38卷 370-372页

作者： Tutty, OR Hackenberg, P Nelson, PA Univ Southampton Sch Engn Sci Southampton SO17 1BJ Hants England Univ Southampton Inst Sound & Vibrat Res Southampton SO17 1BJ Hants England

Eight years ago, Southampton initiated a program of research into the experimental application of distributed suction for the automatic control of boundary-layer transition. In addition to the experimental work, a complementary program of theoretical work was performed. This work was aimed at both modeling the experiments and extending the scope of the research by considering more suction panels and more realistic geometries. The resulting data was analyzed.

关键词： Numerical Optimization Laminar Flow Freestream Velocity Adverse Pressure Gradient Freestream Turbulence solution algorithm Operating Costs NACA Airfoil Wind Tunnels Vortices

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INTERFERENCE FLOWS PAST CYLINDER-FIN-STING-CAVITY ASSEMBLIES

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JOURNAL OF AIRCRAFT 1992年第2期29卷 194-202页

作者： BAYSAL, O FOULADI, K LEUNG, RW SHEFTIC, JS Old Dominion University NorfolkVirginia 23529 Lockheed Missiles and Space Company Inc. SunnyvaleCalifornia 94089

A computer code, VISCC, is developed to solve the three-dimensional, Reynolds-averaged, unsteady, compressible, and complete Navier-Stokes equations. The equations are solved by an implicit, fully vectorized, finite-volume, upwind-biased, approximately factored, and multigrid method. A hybrid domain decomposition method is developed to utilize the combined advantages of overlapped grids, zonal grids, and block-structured grids. An algebraic turbulence model is developed to represent the Reynolds stresses. The store considered here for simulation is a missile configuration with four tail fins and an L-shaped offset sting. The missile is placed first directly above the opening of a rectangular box cavity, then submerged completely inside the cavity. These two cases represent two distinct and important interference characteristics for an internal store carriage and a subsequent separation. The freestream Mach and the unit Reynolds numbers are 2.75 and 2.97 million per foot, respectively. The results of the time-accurate computations depict these complex flows and help understanding the interference effects between the store and the cavity. These effects are more pronounced when the store is placed inside the parent body. The time-averaged surface pressures compare well with the wind-tunnel data.

关键词： Boundary Layer Thickness Aerodynamic Simulation Supersonic Flow Wind Tunnel Tests Pressure Coefficient Vortex Shedding Navier Stokes Equations solution algorithm Inviscid Flow Equations Flight Testing

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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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Retrodictor-Corrector Filter

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2017年第9期40卷 2329-2333页

作者： Modenini, Dario Zannoni, Marco Tortora, Paolo Univ Bologna Dept Ind Engn Via Fontanelle 40 I-47121 Forli Italy

The retrodictor–corrector filter (RCF) algorithm belongs to the first family of filters and consists of a single-stage recursive scheme, based upon a generalization of the iterated extended Kalman filter. The motivating idea stems from recognizing an approximation shared by the nonlinear recursive methods, which is inherent to their predictor–corrector structure. Having obtained estimates for the state and error covariance matrix at a certain time instant, say k − 1, the estimate at the subsequent measurement instant k is computed through two steps. Despite its intuitive nature, the predictor step can be performed exactly only in the linear filtering problem, leading to the well-celebrated KF, whereas its extension to the nonlinear case gives rise to a certain degree of approximation, due to the fact that one needs to propagate through a nonlinear transformation the first and second moment of a random variable.

关键词： Unscented Kalman Filter Power Spectral Density Numerical Integration Three Axis Magnetometer Earth's Magnetic Field Nonlinear Dynamics Nonlinear Filter Monte Carlo Simulation Numerical Simulation solution algorithm

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Finite volume discretization aspects for viscous flows on mixed unstructured grids

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AIAA JOURNAL 1999年第2期37卷 177-184页

作者： Haselbacher, A McGuirk, JJ Page, GJ Univ Loughborough Dept Aeronaut Engn Loughborough LE11 3TU Leics England

A solution method for compressible turbulent flows on unstructured grids in two dimensions is described. The method can be used on grids consisting of triangular and/or quadrilateral cells. Control volumes are constructed from dual cells, and the solution variables are stored at the vertices of the grid. Grid-transparent algorithms are developed that do not require knowledge of cell types, leading to simple discretization schemes on mixed grids. The inviscid fluxes are computed from limited high-resolution schemes originally developed for unstructured triangular grids. They are easily applied to quadrilateral or mixed grids and are grid transparent. The discretization of the viscous fluxes is studied in detail. A positive, grid-transparent discretization of Laplace's equation is developed, The existence of tangential derivatives in the viscous terms prevents grid transparency. By neglecting tangential derivatives, an approximate form of the viscous fluxes is developed, which recovers grid transparency. The approximate form is shown to be similar to the thin-shear-layer approximation. Results are obtained for a transonic inviscid flow, a laminar separated flow, and a transonic turbulent flow. Different control-volume constructions and quadrilateral, triangular, and mixed grids are assessed using a grid-refinement study. The approximate form of the viscous fluxes is investigated in detail.

关键词： Unstructured Grid Laplace Equation Shear Layers Viscous Flow NACA 0012 solution algorithm Eddy Viscosity Navier Stokes Equations Euler Equations Eddy Viscosity Turbulence Models

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Comparative Study Between Cubic and Ellipsoidal Fokker-Planck Kinetic Models

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AIAA JOURNAL 2019年第6期57卷 2524-2533页

作者： Jun, Eunji Pfeiffer, Marcel Mieussens, Luc Gorji, M. Hossein German Aerosp Ctr DLR DLR Site Gottingen German Aerosp Ctr DLR Bunsenstr 10 D-37073 Gottingen Germany Univ Stuttgart Inst Space Syst Pfaffenwaldring 29 D-70569 Stuttgart Germany Univ Bordeaux Bordeaux INP INRIA IMBCNRSUMR 5251 F-33400 Talence France EPF Lausanne Computat Math & Simulat Sci Dept Math Lausanne Switzerland

Motivated by improving the performance of particle-based Monte-Carlo simulations in the transitional regime, Fokker-Planck kinetic models have been devised and studied as approximations of the Boltzmann collision operator. By generalizing the linear drift model, the cubic Fokker-Planck (cubic-FP) and ellipsoidal Fokker-Planck (ES-FP) have been proposed, in order to obtain the correct Prandtl number of 2/3 for a dilute monatomic gas. This study provides a close comparison between both models in low Mach and supersonic settings. While direct simulation Monte-Carlo (DSMC) here serves as the benchmark, overall close performance between cubic-FP, ES-FP, and DSMC is observed. Furthermore, while the ES-FP outperforms the cubic-FP model in the shock region of the supersonic flow around a cylinder, the latter shows a better accuracy in the near continuum regime. It is argued that the reason behind these discrepancies lies in the entropy law besides the transport properties.

关键词： Direct Simulation Monte Carlo Flow Conditions Prandtl Number Entropy Number of Particles Diffusion Coefficient Knudsen Numbers Free Stream Velocity Velocity Profiles solution algorithm

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PROBABILITY DENSITY-FUNCTION APPROACH FOR MULTIDIMENSIONAL TURBULENT-FLOW CALCULATIONS WITH APPLICATION TO IN-CYLINDER FLOWS IN RECIPROCATING-ENGINES

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AIAA JOURNAL 1991年第2期29卷 208-218页

作者： HAWORTH, DC ELTAHRY, SH General Motors Research Laboratories Warren Michigan 48090

The probability density function (pdf) method is extended to two- and three-dimensional transient turbulent flows. The numerical approach couples a Lagrangian Monte Carlo method to solve for the joint pdf of velocity and scalar compositions with an Eulerian finite-volume algorithm to calculate mean pressure and a turbulence time scale. A general approach applicable to variable-density chemically reacting flows has been taken;the present results are for nearly uniform density inert flows. Three engine-like configurations have been investigated: 1) a noncompressing axisymmetric cylinder-piston assembly with a central port;2) a noncompressing axisymmetric cylinder-piston assembly with an annular port;and 3) a compressing three-dimensional configuration with an off-center valve. Pdf results are compared with measurements and with conventional k-epsilon calculations for the two axisymmetric geometries. For these noncompressing flows the pdf approach is found to have little advantage over a k-epsilon model. Mean velocity profiles from both models are in good agreement with experiment for the central port case, whereas agreement for the annular port is less satisfying. Root-mean-square axial velocities from both models are low at early times in the intake process, but improve later in the cycle. Influence of numerical parameters on solution accuracy is assessed. The present work confirms the feasibility of the pdf approach for complex turbulent flows and represents an intermediate step in the application of pdf methods to multidimensional turbulent reacting flows, where they are expected to offer their greatest advantage.

关键词： Reciprocating Engine Kinematic Viscosity Axisymmetric Flow Monte Carlo Method Chemically Reacting Flow Reynolds Stress Kinetic Energy Turbulence Models Number of Particles solution algorithm

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