Numerical Study of Separated Turbulent Flow Over Airfoils PDF Download
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Author: Ananthanarayanan Sugavanam
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 252
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Book Description
Author: Ananthanarayanan Sugavanam
Publisher:
ISBN:
Category : Aerofoils
Languages : en
Pages : 252
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Turbulent boundary layer separation was studied numerically using a special code to integrate the model equations for transient two-dimensional turbulent flow. For three calculations, separation was induced by interaction of a boundary layer with oblique shock waves; for three others, separation was caused by flow into the compression corner formed by an adiabatic flat-plate and ramp. In every case the free-stream Mach number was 2.96, the Reynolds number based on boundary layer thickness just upstream of the interaction region ranged from 1/4 to 1 million, and the static pressure rose by a factor of either 3.7 or 5.1.
Author: Zaffar Mahmood
Publisher:
ISBN:
Category :
Languages : en
Pages : 485
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Book Description
The present research work has been concerned with the measurement and computation of incompressible turbulent flow development around single and multi-element aerofoils. Detailed measurements of the mean velocity and turbulence stress fields over NACA 4412 aerofoil and NACA 4415 flap section are made using a flying hot-wire system. The results are analyzed and characteristics of the mean flow and turbulence field development as a function of angle of attack and flap gap/deflection are presented. The results indicate increasing intermittent separation over single aerofoil with increase in angle of incidence. A large separation is observed for multi-element cases at large incidences (......) accompanied by high turbulence levels observed in the separated shear layers. The effectiveness of the flap in the multi-element aerofoil as a source of additional lift is observed only at low angles of attack (......) and with moderate flap deflections only. The numerical computations are carried out by solving Reynolds-averaged, Navier-Stokes equations employing both the standard .... and Reynolds stress (RSM) turbulence models using a commercially available CFD package. The problems associated with geometry complexity, deriving from closely coupled configuration of multi-element aerofoils, are overcome by employing structured computational grids using curvilinear coordinates. The comparison of computations with experimental results for single element aerofoil gives reasonable accuracy at low angles of attack (....) using both turbulence models. However, for the multi-element aerofoil discrepancies are observed near the trailing edge of the main aerofoil at large incidences even with RSM, implying the insufficient and simplifying assumptions used in modeled terms which are unable to deal with complex flow features observed in the present investigation. It is recommended that the various modeled terms (such as pressure-strain) be reexamined to take into account the curved mixing layers.
Author: Paul K. Chang
Publisher: Elsevier
ISBN: 1483181286
Category : Technology & Engineering
Languages : en
Pages : 800
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Book Description
Interdisciplinary and Advanced Topics in Science and Engineering, Volume 3: Separation of Flow presents the problem of the separation of fluid flow. This book provides information covering the fields of basic physical processes, analyses, and experiments concerning flow separation. Organized into 12 chapters, this volume begins with an overview of the flow separation on the body surface as discusses in various classical examples. This text then examines the analytical and experimental results of the laminar boundary layer of steady, two-dimensional flows in the subsonic speed range. Other chapters consider the study of flow separation on the two-dimensional body, flow separation on three-dimensional body shape and particularly on bodies of revolution. This book discusses as well the analytical solutions of the unsteady flow separation. The final chapter deals with the purpose of separation flow control to raise efficiency or to enhance the performance of vehicles and fluid machineries involving various engineering applications. This book is a valuable resource for engineers.
Author: James C. Wu
Publisher: Springer
ISBN: 3662440407
Category : Technology & Engineering
Languages : en
Pages : 147
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Book Description
This book opens with a discussion of the vorticity-dynamic formulation of the low Mach number viscous flow problem. It examines the physical aspects of the velocity and the vorticity fields, their instantaneous relationship, and the transport of vorticity in viscous fluids for steady and unsteady flows. Subsequently, using classical analyses it explores the mathematical aspects of vorticity dynamics and issues of initial and boundary conditions for the viscous flow problem. It also includes the evolution of the vorticity field which surrounds and trails behind airfoils and wings, generalizations of Helmholtz’ vortex theorems and the Biot-Savart Law. The book introduces a theorem that relates the aerodynamic force to the vorticity moment and reviews the applications of the theorem. Further, it presents interpretations of the Kutta-Joukowski theorem and Prandtl’s lifting line theory for vorticity dynamics and discusses wake integral methods. The virtual-mass effect is shown to be the seminal event in unsteady aerodynamics and a simple approach for evaluating virtual-mass forces on the basis of vorticity dynamics is presented. The book presents a modern viewpoint on vorticity dynamics as the framework for understanding and establishing the fundamental principles of viscous and unsteady aerodynamics. It is intended for graduate-level students of classical aerodynamics and researchers exploring the frontiers of fully unsteady and non-streamlined aerodynamics.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Turbulent boundary layer separation was studied numerically using a special code to integrate the model equations for transient two-dimensional turbulent flow. For three calculations, separation was induced by interaction of a boundary layer with oblique shock waves; for three others, separation was caused by flow into the compression corner formed by an adiabatic flat-plate and ramp. In every case the free-stream Mach number was 2.96, the Reynolds number based on boundary layer thickness just upstream of the interaction region ranged from 1/4 to 1 million, and the static pressure rose by a factor of either 3.7 or 5.1.
Author: S. M. Belotserkovsky
Publisher: CRC Press
ISBN: 9780849393068
Category : Technology & Engineering
Languages : en
Pages : 322
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Book Description
Two-Dimensional Separated Flows provides a systematic presentation of the theory of separated flow around bodies. The main classes of aerodynamic problems of plane-parallel flow around bodies are described, and the steady aerodynamic, unsteady aerodynamic, and statistical characteristics of a trailing wake are determined. Numerical methods based on the synthesis of models for non-viscous incompressible flow and boundary layer, algorithms, examples, and systematic comparisons are presented. The book also includes numerical results for the problem of separated flow around fixed, oscillating, and rotating cylinders, in addition to results for separated flow around an aerofoil over a wide range of angles. Two-Dimensional Separated Flows will benefit researchers and students studying aerodynamics, aircraft dynamics, aeroelasticity, and the aerodynamics of building structures.
Author: Yunpeng Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 408
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Book Description
Author: Vincent DeHenau
Publisher:
ISBN:
Category :
Languages : en
Pages : 183
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Book Description
Author: Shao-Chi Huang
Publisher:
ISBN:
Category :
Languages : en
Pages : 53
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Book Description
In a recent study, Lu, Aithal & Ferrante (AIAA J., 2021) have discovered the law of incipient separation for curved ramps that predicts the incipiency of flow separation by knowing only a few geometrical parameters of the ramp and the Reynolds number of the incoming flow. In the present study, we have searched for a similar law to predict the separation of the turbulent flow over airfoils. With that goal, we have conducted two-dimensional Reynolds averaged Navier-Stokes (RANS) wall-resolved simulations of incompressible turbulent flows over several airfoils over a range of angles of attack. Along the study, we have carried out verification and validation of RANS using the Spalart-Allmaras model against the experimental measurements by Wadcock (NASA-CR-177450, 1987) for the turbulent flow over a NACA4412 airfoil at a Reynolds number based on the airfoil chord length of Re = 1640000. From such comparison, we have found that although the RANS prediction fails when the airfoil approaches its maximum lift (alpha
