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Author: R. M. Traci Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 126
Book Description
A theory and numerical solution method are presented for the problem of two-dimensional unsteady transonic flow about thin airfoils undergoing harmonic oscillation. The theory is based on a treatment of the unsteady flow as a small perturbation on the non-linear steady flow. The governing equations for the steady and unsteady perturbation potentials are of mixed elliptic/hyperbolic type and are solved by the mixed differencing line relaxation technique of Murman and Cole. Detailed steady and unsteady calculations are performed and compared when possible to available experimental data. The solution procedure is found to be highly efficient and promises further improvements in efficiency through the use of extrapolation schemes. Also the method can be generalized in a straightforward manner to perform calculations with supersonic freestreams and three-dimensional finite wing calculations. (Author).
Author: R. M. Traci Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 126
Book Description
A theory and numerical solution method are presented for the problem of two-dimensional unsteady transonic flow about thin airfoils undergoing harmonic oscillation. The theory is based on a treatment of the unsteady flow as a small perturbation on the non-linear steady flow. The governing equations for the steady and unsteady perturbation potentials are of mixed elliptic/hyperbolic type and are solved by the mixed differencing line relaxation technique of Murman and Cole. Detailed steady and unsteady calculations are performed and compared when possible to available experimental data. The solution procedure is found to be highly efficient and promises further improvements in efficiency through the use of extrapolation schemes. Also the method can be generalized in a straightforward manner to perform calculations with supersonic freestreams and three-dimensional finite wing calculations. (Author).
Author: J. L. Farr (Jr.) Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 140
Book Description
Computer programs are described which implement a small disturbance potential flow theory for the two-dimensional unsteady transonic flow about thin airfoils undergoing low reduced frequency harmonic oscillations. The theory is based upon the treatment of the unsteady flow as a small perturbation to the steady transonic flow. Separating the perturbation potential into a steady and unsteady component results in a pair of coupled boundary value problems for the components. The governing equation for the steady perturbation potential is the usual nonlinear transonic potential equation and it is solved in computer program STRANS using the mixed differencing relaxation procedure of Murman and Cole. The governing equation for the unsteady perturbation potential is linear and, for the harmonic boundary disturbance considered, of mixed elliptic hyperbolic type depending on the local nature of the steady potential. Using a steady solution previously generated by STRANS, computer program UTRANS solves the unsteady potential equation by the same relaxation procedure. The solution procedures are found to be quite efficient, permitting the calculation of unsteady aerodynamic forces to engineering accuracy in a few minutes on a CDC 6600 computer.
Author: R. M. Traci Publisher: ISBN: Category : Languages : en Pages : 179
Book Description
A theory and numerical solution method are presented for the problem of two or three dimensional flow about thin wings undergoing harmonic oscillations. The theory is based on a treatment of the unsteady flow as a small perturbation on the nonlinear steady flow. The coupled governing equations for the steady and unsteady perturbation potentials are of mixed elliptic/hyperbolic type and are solved using the mixed differencing line relaxation techniques of Murman and Cole. The theory and solution method have been generalized to treat subsonic or supersonic freestream flows, solid or porous wall effects and three dimensional flow about planar wings. Calculations demonstrating each of these capabilities are presented. Accuracy of the method for realistic steady and unsteady flows is examined by comparison to more exact numerical results and experimental data. The comparison indicates that the present method provides a useful and efficient inviscid solution. Quantitative differences between the present results and experimental data are attributed primarily to viscous effects, pointing out the importance of such effects for transonic flows.
Author: Christopher J. Borland Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 78
Book Description
A bibliography of recent developments in unsteady transonic flow is presented. Papers have been divided into survey, experimental, and theoretical classifications, selected publications have been reviewed, and a more comprehensive set of publications has been listed and summarized in tabular form. Primary emphasis has been placed on numerical solution of unsteady transonic flow problems. Relevant steady methods have been included. (Author)
Author: Wilson Chin Publisher: John Wiley & Sons ISBN: 1119580862 Category : Technology & Engineering Languages : en Pages : 363
Book Description
A powerful new monograph from an aerodynamicist reviewing modern conventional aerodynamic approaches, this volume covers aspects of subsonic, transonic and supersonic flow, inverse problems, shear flow analysis, jet engine power addition, engine and airframe integration, and other areas, providing readers with the tools needed to evaluate their own ideas and to implement the newer methods suggested in this book. This new book, by a prolific fluid-dynamicist and mathematician who has published more than twenty research monographs, represents not just another contribution to aerodynamics, but a book that raises serious questions about traditionally accepted approaches and formulations, providing new methods that solve longstanding problems of importance to the industry. While both conventional and newer ideas are discussed, the presentations are readable and geared to advanced undergraduates with exposure to elementary differential equations and introductory aerodynamics principles. Readers are introduced to fundamental algorithms (with Fortran source code) for basic applications, such as subsonic lifting airfoils, transonic supercritical flows utilizing mixed differencing, models for inviscid shear flow aerodynamics, and so on. These are models they can extend to include newer effects developed in the second half of the book. Many of the newer methods have appeared over the years in various journals and are now presented with deeper perspective and integration. This book helps readers approach the literature more critically. Rather than simply understanding an approach, for instance, the powerful "type differencing" behind transonic analysis, or the rationale behind "conservative" formulations, or the use of Euler equation methods for shear flow analysis when they are unnecessary, the author guides and motivates the user to ask why and why not and what if. And often, more powerful methods can be developed using no more than simple mathematical manipulations. For example, Cauchy-Riemann conditions, which are powerful tools in subsonic airfoil theory, can be readily extended to handle compressible flows with shocks, rotational flows, and even three-dimensional wing flowfields, in a variety of applications, to produce powerful formulations that address very difficult problems. This breakthrough volume is certainly a "must have" on every engineer's bookshelf.
Author: F. Edward Ehlers Publisher: ISBN: Category : Aerodynamics, Transonic Languages : en Pages : 88
Book Description
A finite difference method for the solution of the transonic flow about a harmonically oscillating wing is presented. The partial differential equation for the unsteady transonic flow was linearized by dividing the flow into separate steady and unsteady perturbation velocity potentials and by assuming small amplitudes of harmonic oscillation. The resulting linear differential equation is of mixed type, being elliptic or hyperbolic whereever the steady flow equation is elliptic or hyperbolic. Central differences were used for all derivatives except at supersonic points where backward differencing was used for the streamwise direction. Detailed formulas and procedures are described in sufficient detail for programming on high speed computers. To test the method, the problem of the oscillating flap on a NACA 64A006 airfoil was programmed. The numerical procedure was found to be stable and convergent even in regions of local supersonic flow with shocks.
Author: R. M. Traci
Author: R. M. Traci
Author: J. L. Farr (Jr.)
Author: R. M. Traci
Author: 
Author: Christopher J. Borland
Author: 
Author: Liu Gao-lian
Author: Wilson Chin
Author: F. Edward Ehlers
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