Download or read book Numerical Simulation of Transonic Flow Around Airfoils at High Reynolds Numbers Using Algebraic Turbulence Models written by Jaakko Hoffren and published by . This book was released on 1990 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Numerical Simulation and Stability Analysis of Transonic Flow Around Airfoils at Moderate Reynolds Numbers written by Markus Zauner and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Calculation of Viscous Transonic Flows about a Supercritical Airfoil written by Miguel R. Visbal and published by . This book was released on 1986 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Navier Stokes Calculations of Transonic Flows Past Cavities written by Oktay Baysal and published by . This book was released on 1989 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Numerical Simulation of Flow Over a NACA0025 Airfoil Using Large Eddy Simulation Turbulence Models written by Babak Babaee Owlam and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability of computational fluid dynamic (CFD) to predict critical flow characteristics has always been questionable. Flow separation over lifting surfaces such as airfoils are one of the critical features which can significantly deteriorate their aerodynamic performances. The purpose of this research is to evaluate the accuracy of two CFD methods in predicting the flow separation over a NACA0025 airfoil at low Reynolds numbers. The first code is an in-house code which is based on a 3D compressible Navier-Stokes solver with preconditioning and self-adaptive upwinding methods. The second code is the commercial FLUENT software. In order to accurately simulate the laminar boundary layer separation, the Large Eddy Simulation (LES) method is used for turbulence modeling of both codes. Results comparison shows that Fluent is not able to capture this feature. In addition the results are also compared with another similar numerical simulation and validated with available experimental data.

Download or read book Numerical Studies of Unsteady Transonic Flow Over an Oscillating Airfoil written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-24 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: A finite-difference solution to the Navier-Stokes equations combined with a time-varying grid-generation technique was used to compute unsteady transonic flow over an oscillating airfoil. These computations were compared with experimental data (obtained at Ames Research Center) which form part of the AGARD standard configuration for aeroelastic analysis. A variety of approximations to the full Navier-Stokes equations was used to determine the effect of frequency, shock-wave motion, flow separation, and airfoil geometry on unsteady pressures and overall air loads. Good agreement is shown between experiment and theory with the limiting factor being the lack of a reliable turbulence model for high-Reynolds-number, unsteady transonic flows. Chyu, W. J. and Davis, S. S. Ames Research Center NASA-TM-86011, A-9857, NAS 1.15:86011

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Numerical Simulation of Three dimensional Transonic Flow with Application to the C 141 Wing written by Harvard Lomax and published by . This book was released on 1973 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results computed by a finite-difference, relaxation algorithm are presented for the supercritical flow (M = 0.825) about the C-141 airplane wing, which has sweep, taper, and twist. Comparisons with both wind-tunnel and flight data indicate that computed solutions of the classical transonic small disturbance equation can accurately simulate high Reynolds number flows when the shock sweep angle is small. It is also shown that this equation poorly approximates the complete potential equation when embedded shock waves are swept at angles greater than about 15 deg. Hence, a more consistent small disturbance equation is derived for use in more general cases.

Download or read book Fluent Simulation of Airflow Around Airfoils written by Chunlin Liu and published by . This book was released on 2008 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical simulation of flow past airfoils is important in the aerodynamics design of aircraft. The complex commercial computational fluid dynamics software FLUENT provide a convenient way to model fluid flow dynamics problem. To test accuracy of CFD in predicting Lift and Drag coefficient under a wide range of flow conditions. In this thesis, numerical simulation of steady flow around NACA 0012 was conducted using control volume approach in Gambit and Fluent at three different Reynolds Number(Re), 1.0x10[superscript]6, 3.0x10[superscript]6 and 5x10[superscript]6. Lift and drag coefficient were measured for an attack angle between 0[degree] and 16[degree] in 2[degree] intervals. The purpose of this study was to establish a verified solution method in the subsonic and transonic flow regimes around airfoil. The results from FLUENT model were found closely to the published experimental data except for the stall point of the airfoil. The flow field is determined by solving two-dimensional incompressible Navier-Stokers equations while the effects of turbulence are accounted for by the Spalart-Allmaras model. Boundary layer developed at the surfaces of the airfoil is investigated together with relevant pressure and velocity contours for different Attack angle and Reynolds Number. This study shows that CFD can provide accurate predictions under the flow conditional scheduling.

Download or read book Numerical Simulation of the Transonic DFVLR F5 Wing Experiment written by Wilhelm Kordulla and published by . This book was released on 1988 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boundary Value Problems for Transonic Flow written by Alexander G Kuz'min and published by John Wiley & Sons. This book was released on 2003-02-28 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Reynolds Number Effects in Transonic Flow written by A. Elsenaar and published by . This book was released on 1988 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reynolds number effects in transonic flow are critically reviewed. This review, which may be considered a supplement to AR 224 'Boundary Layer Simulation and Control in Wind Tunnels', is mainly concered with a discussion of viscous effects actually observed on realistic configurations. The following geometries are considered: Airfoils and high aspect ratio wings typical and transport aircraft, fighter-type low aspect ratio delta wings, tow- and three-dimensional bodies characteristic of missiles and combat aircraft fuselages, and afterbodies. "Pseudo"--Reynolds number on the wind tunnel environment and in turn affect the flow about a model. As an introduction, a brief retrospect of the "history" of Reynolds number effect is presented. This AGARDograph has been produced at the request of the Fluid Dynamics Panel of AGARD.

Download or read book Aeronautical Engineering written by and published by . This book was released on 1991 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Airfoil Characteristics With Higher Order Turbulence Models written by Thomas B. Gatski and published by . This book was released on 1996 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study focuses on the prediction of airfoil characteristics, including lift and drag over a range of Reynolds numbers. Two different turbulence models, which represent two different types of models, are tested. The first is a standard isotropic eddy-viscosity two-equation model, and the second is an explicit algebraic stress model (EASM). The turbulent flow field over a general-aviation airfoil (GA(W)-2) at three Reynolds numbers is studied. At each Reynolds number, predicted lift and drag values at different angles of attack are compared with experimental results, and predicted variations of stall locations with Reynolds number are compared with experimental data. Finally, the size of the separation zone predicted by each model is analyzed, and correlated with the behavior of the lift coefficient near stall. In summary, the EASM model is able to predict the lift and drag coefficients over a wider range of angles of attack than the two-equation model for the three Reynolds numbers studied. However, both models are unable to predict the correct lift and drag behavior near the stall angle, and for the lowest Reynolds number case, the two-equation model did not predict separation on the airfoil near stall.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: