Author: Chung-Lung ChenPublisher:
ISBN:
Category :
Languages : en
Pages : 16
Book Description
Computation of Viscous Transonic Flow Over Porous Airfoils
Author: Chung-Lung ChenComputation of Transonic Flow Over Porous Airfoils
Author: Chung-Lung ChenPublisher:
ISBN:
Category : Aerodynamics, Transonic
Languages : en
Pages : 206
Book Description
Computation of Viscous Transonic Flow about a Lifting Airfoil
Author: Calculation of Viscous Effects on Transonic Flow for Oscillating Airfoils and Comparisons with Experiment
Author: James T. HowlettGrumfoil: a Computer Code for the Computation of Viscous Transonic Flow Over Airfoils
Author: R.E. MelnikBoundary Value Problems for Transonic Flow
Author: Alexander G Kuz'minPublisher: John Wiley & Sons
ISBN: 047085295X
Category : Technology & Engineering
Languages : en
Pages : 316
Book Description
Transonic flow occurs around moving objects as they approach and cross the sound barrier. Serious problems can occur at this point, such as shock-induced flow separation which can cause the aircraft to spin out of control. Another important practical problem is the achievement of higher aerodynamic performance of aircraft at cruise conditions, which leads to considerable fuel savings. The success in application of numerical methods for simulation of transonic flow and aircraft design depends on developments in the underlying mathematical theory. This book presents a breakthrough in the solvability analysis of boundary value problems, which makes it possible to establish convergence of finite element approximations for shock-free flow and to provide a framework for putting the existing numerical methods on a more sound basis. Also, physical aspects concerned with patterns of formation and propagation of weak shock waves are analysed. This contributes to the understanding of the extreme sensitivity of transonic flow to perturbation of freestream conditions. The developed theoretical knowledge base yields promising concepts of the airfoil design and active flow control by airfoil/wing shape modifications or suction/blowing through a perforated surface. Boundary Value Problems for Transonic Flow * Focuses on Computational Fluid Dynamics. * Addresses practical problems, such as airfoil design and flow control. * Presents developments made in the last two decades. In essence this is a much needed monograph for researchers and engineers in applied mathematics and numerical analysis applied to aerodynamics and for algorithm developers in Computational Fluid Dynamics in the aircraft industry. It gives design engineers the underlying mathematical theory necessary for developing new concepts for airfoil/wing design and flow control.
The Viscous Transonic Flow Over Two-Element Airfoil Systems
Author: G. VolpePublisher:
ISBN:
Category :
Languages : en
Pages : 49
Book Description
A numerical procedure has been developed to compute the transonic viscous-inviscid interacting flow field about airfoils with leading edge slats or trailing edge flaps. The inviscid theory utilizes conformal mappings in a full potential flow formulation, with analytic removal of singularities and a mixed flow relaxation procedure. The turbulent boundary layer is computed with methods based on a turbulent kinetic energy formulation and is coupled to the inviscid flow using surface source flow boundary conditions. Semiempirical methods are used to compute local strong interaction regions occurring in the vicinity of shock waves, trailing edges, and to account for flow separation. Our results are in good agreement with existing wind tunnel data for several typical two-element airfoil configurations. (Author).
Numerical Study of Porous Airfoils in Transonic Flow
Author: Viscous-inviscid Interaction in Transonic Flow
Author: Laurence Byron WigtonPublisher:
ISBN:
Category :
Languages : en
Pages : 244
Book Description
The aim of this thesis is to couple an inviscid two dimensional steady transonic flow calculation with a boundary layer calculation. This interaction is especially important in transonic problems since the boundary layer has a significant effect on the inviscid portion of the flow. Here, the inviscid solution is obtained by an algorithm developed for the full potential equation by Holst and Ballhaus while the attached and separated turbulent boundary layer calculations are performed by Green's lag entrainment method. Guided by a model problem suggested by Le Balleur, a viscous-inviscid coupling algorithm is developed. Theoretical analysis indicates that it coverages rapidly for attached flows ad also performs well for separated flows. These conclusions are confirmed through a series of challenging transonic calculations involving both attached and separated flows. The coupling algorithm is remarkably stable and allows computation of coupled viscous-inviscid flows within times required to perform the inviscid calculations by themselves. (Author).
Calculation of Viscous Transonic Flows about a Supercritical Airfoil
Author: Miguel R. VisbalPublisher:
ISBN:
Category :
Languages : en
Pages : 94
Book Description
A critical examination of several aspects of the numerical simulation of high Reynolds number transonic airfoil flows is presented. Subcritical and supercritical flow fields about an aft-cambered airfoil were generated by solving the mass-averaged Navier-Stokes equations with turbulence incorporated through an algebraic eddy viscosity model. The governing equations were solved on curvilinear body-fitted grids utilizing two different algorithms., i.e., MacCormack's explicit and Beam-Warming implicit. The numerical uncertainties associated with different schemes, grid resolution, artificial viscosity and far field boundary placement were investigated and found to be of the same order of magnitude or less than the corresponding uncertainties in the available experimentat data. Comparison of computed and experimental results showed good prediction of all the essential flow features. However, detailed comparison of velocity profiles pointed out deficiencies of the turbulence model downstream of the shock/boundary layer interaction in the airfoil cove and in the near-wake. Thin-layer and Navier-Stokes computed results were found in excellent agreement with each other. However, the Euler equations failed to provide a reasonable approximation of the flow due to the dramatic viscous-inviscid interaction effects for supercritical airfoils. Keywords: Computational fluid dynamics, MacCormack's explicit algorithm, Transonic flow, and Numerical methods and procedures.