检索结果-内蒙古大学图书馆

IMPLICIT CONSERVATIVE SCHEMES FOR THE EULER EQUATIONS

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

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

CALCULATION OF UNSTEADY FAN ROTOR RESPONSE CAUSED BY DOWNSTREAM FLOW DISTORTIONS

引用

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

来源：评论

学校读者我要写书评

暂无评论

PREDICTION OF SECONDARY VORTEX FLOWFIELDS GENERATED BY AN INTERACTING MULTIPLE FREE-JET CONFIGURATION

引用

AIAA JOURNAL 1985年第7期23卷 983-984页

作者： BAKER, AJ ORZECHOWSKI, JA STUNGIS, GE COMPUTAT MECH CONSULTANTS INC KNOXVILLETN BROWN & WILLIAMSON TOBACCO CORP LOUISVILLEKY

A PENALTY finite element algorithm for solution of the three-dimensional parabolic Navier-Stokes equations for subsonic turbulent flows is applied to the prediction of secondary vortex flowfields induced by a multiple free-jet configuration. The combined action of rapid decay of the initial high-speed parallel jets, turbulence level, induced entrainment from the far field, and geometric discreteness of a four-jet configuration, is predicted to produce a persistent system of eight counterrotating vortex pairs in the plane normal to the initial jet axis. Numerical predictions are interpreted and compared with available experimental data. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Vortex Structure Subsonic Turbulent Flow Navier Stokes Equations Smoke Flow Visualization Continuity Equation Poisson's Equation Numerical algorithms solution algorithm Computer Programs Streamtube

来源：评论

学校读者我要写书评

暂无评论

INTERACTIVE GRAPHICS FOR GEOMETRY GENERATION - A PROGRAM WITH A CONTEMPORARY DESIGN

引用

JOURNAL OF AIRCRAFT 1985年第12期22卷 1054-1058页

作者： LABOZZETTA, WF COLE, PE Lockheed-Georgia Company Marietta Georgia

The aerodynamic design process is now strongly influenced by the application of advanced computational tools due mainly to recent advances in computer capabilities. Today’s aerodynamic analysis codes require large amounts of geometric data to define the surfaces in sufficient detail for proper analysis. A program has been developed to aid the engineer in generating geometric models for computational aerodynamics codes. The program, Interactive Graphics for Geometry Generation (I3G), is not dramatically different on the “outside” from other interactive graphics programs of this type. It is, however, different on the “inside,” i.e., in how it performs its functions. I3G is capable of accepting input from a variety of geometry sources and can support the generation of geometric models for many different computational codes. User-friendly operation encourages program use. Graphics devices ranging from sophisticated systems to low-cost display-only terminals can be easily supported by I3G. The program’s modular structure allows new modeling capabilities to be readily incorporated. A system for indexing and retrieving existing geometric models is available to the user. In summary, “flexibility” is the key word behind I3G’s basic design and structure. This feature allows modifications and enhancements to be readily made as needs change or arise. Succinctly, it is a program designed to last. © 1985 American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Computational Aerodynamics Data Store CAD System Data Storage Aerodynamic Codes Interactive Computer Graphics Structured Programming solution algorithm Computing Hardware

来源：评论

学校读者我要写书评

暂无评论

BOUNDARY-LAYER THICKNESS AND BASE-PRESSURE

引用

AIAA JOURNAL 1985年第12期23卷 1987-1989页

作者： TANNER, M Institut fur Theoretische Stromungsmechanik DFVLR Gottingen Federal Republic of Germany

An inviscid supersonic flow past a backward-facing step is correlated with a corresponding flow of a viscous fluid. The theoretical influence of the boundary-layer thickness in the base pressure coefficient for variou... 详细信息

关键词： Boundary Layer Thickness Freestream Mach Number Pressure Coefficient Supersonic Flow Viscous Fluid Vortex Sheet Aspect Ratio Navier Stokes Equations Continuity Equation solution algorithm

来源：评论

学校读者我要写书评

暂无评论

ANALYTIC FOURIER-TRANSFORM FOR A CLASS OF FINITE-TIME CONTROL-PROBLEMS

引用

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 1985年第4期8卷 539-541页

作者： TURNER, JD CHUN, HM CHARLES STARK DRAPER LAB INC CAMBRIDGEMA 02139

A computationally efficient algorithm has been presented for obtaining the complex Fourier transform of a class of vector functions that frequently occur in modern control theory. The basic algorithm requires (1) the evaluation of a single matrix exponential for the dynamics of the time-varying control;(2) the solution for either the right and left eigenvectors or a real Schur decomposition of the constant control dynamics matrix;(3) the sequential solution for the reducing subspace transformation vector p;and (4) the evaluation of a single scalar complex exponential.

关键词： Numerical Integration Spacecraft Attitude Euler Angles State Space Representation Linear Quadratic Gaussian Frequency Domain Multivariable Control solution algorithm Stochastic Control Optical Telescopes

来源：评论

学校读者我要写书评

暂无评论

VISCOUS SHOCK-LAYER FLOWFIELD ANALYSIS BY AN EXPLICIT-IMPLICIT METHOD

引用

AIAA JOURNAL 1985年第5期23卷 723-732页

作者： GUPTA, RN GNOFFO, PA MACCORMACK, RW UNIV WASHINGTON DEPT AERONAUT & ASTRONAUTSEATTLEWA 98195

The present work extends the recently reported implicit analog of MacCormack’s earlier, widely used explicit method to external axisymmetric laminar flows with strong entropy gradients. The details of the “numerics” of the implicit part are provided in a body-oriented coordinate system with a moving outer (shock) boundary during the transient part of the solutions. The limiting values of the Courant number are obtained when the shock boundary is treated explicitly. The solution algorithm outlined includes the treatment of the source term associated with the equations in weak conservation form. From the results obtained for two sample problems, it becomes clear that accuracy of predictions is, indeed, very good at higher values of the Courant number. There is a significant saving in overall computing time, depending on the Courant number used and the flow Reynolds number. These properties combined with the simplicity of programming of the implicit analog may appeal to researchers in the analysis of three-dimensional flow problems. © 1985 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.

关键词： Shock Layers In Compressible Viscous Flows Numerical Integration Freestream Mach Number Courant Friedrichs Lewy Heat Transfer Coefficients solution algorithm Gas Constant Viscosity Navier Stokes Equations

来源：评论

学校读者我要写书评

暂无评论

STABILITY OF THE THIN-JET MODEL OF THE UNSTEADY JET FLAP

引用

AIAA JOURNAL 1985年第7期23卷 1118-1120页

作者： PULLIN, DI SIMMONS, JM University of Queensland Brisbane Australia

A jet flap results if air is ejected from a spanwise slot at or near the trailing edge of an airfoil. It produces lift both by the component of thrust in the lift direction and by the modification of circulation around the airfoil. The steady jet flap, for which flow parameters are constant, has received considerable attention because of interest in V/STOL aircraft.

关键词： Jet Flaps Starting Vortex Incompressible Flow Kutta Condition Freestream Linear Interpolation Numerical Stability Bernoulli's Equation solution algorithm Helicopter Rotor

来源：评论

学校读者我要写书评

暂无评论

EFFECT OF CONTACT SPACING ON EFFICIENCY OF FLAT-PLATE SOLAR COLLECTORS

引用

JOURNAL OF SPACECRAFT AND ROCKETS 1985年第6期22卷 585-591页

作者： CRHA, S SCHNEIDER, GE University of Waterloo Ontario Canada

The attachment of an extended surface to an energy removal tube in a noncontinuous manner is considered. Rather than to provide continuous weld or solder to form thermal contact, the use of a uniform distribution of finite regions of contact is examined. In particular, the application to solar energy collection is considered where a discrete, discontinuous system of contacts offers potential economic benefit in the fabrication and reliability aspects of construction. The problem is formulated mathematically in nondimensional terms and numerical solutions employing the finite element method are obtained. Specifically, the sensitivity of the thermal performance of the collector system to weld/solder joint dimensions is presented. It is found that the discontinuous nature of the weld can significantly degrade system performance with the degree of degradation strongly dependent on the fin surface Biot modulus. Further, it is observed that the controlling parameter with respect to the weld dimensions is the perimeter length of the weld location of contact. This observation will permit direct application of the results obtained to situations other than the rectangular weld planform specifically considered. A novel and useful method of representation, in the form of a relative performance ratio, is also introduced and should prove useful in future two-dimensional fin analyses. © American Institute of Aeronautics and Astronautics, Inc., 1985, All rights reserved.

关键词： Flat Plate Solar Collector Finite Element Method Thermal Performance Solar Energy Heat Transfer Coefficients Natural Convection Energy Transfer Heat Exchangers Thermal Conductivity solution algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：