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Study Of Low Speed Turbulent Flow Over High Lift Multi Element Airfoil System Using Overlapping Grid Scheme
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Book Synopsis Study of Low-speed Turbulent Flow Over High-lift Multi-element Airfoil System Using Overlapping-grid Scheme by : Hsueh-Chung Wu
Download or read book Study of Low-speed Turbulent Flow Over High-lift Multi-element Airfoil System Using Overlapping-grid Scheme written by Hsueh-Chung Wu and published by . This book was released on 1995 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :Philippe Godin Publisher :Library and Archives Canada = Bibliothèque et Archives Canada ISBN 13 :9780612942325 Total Pages :272 pages Book Rating :4.9/5 (423 download)
Book Synopsis Turbulence Modeling for High-lift Multi-element Airfoil Configurations [microform] by : Philippe Godin
Download or read book Turbulence Modeling for High-lift Multi-element Airfoil Configurations [microform] written by Philippe Godin and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study provides a detailed comparison of two turbulence closures for aerodynamic flows around high-lift airfoils; the first based on turbulent viscosity and the second on the algebraic Reynolds-stress approximation. A detailed analysis of their derivation helps shed light on their inherent limitations in predicting complex flow phenomena such as confluent boundary layers and flow separation found in typical take-off and landing conditions. One of each of the following categories: one-equation, two-equation, IARSM and EARSM is selected and compared on several low-speed high-lift configurations. Comparisons to experimental data for both mean flow and turbulence quantities are provided for all cases studied. Amongst the turbulent viscosity models coded and studied are the Spalart-Allmaras, Baldwin-Barth, Wilcox k - o and Menter's Shear Stress Transport model. A parameter study based on different pressure-strain correlations and dissipation models (or near-wall treatment) is included when studying the algebraic Reynolds-stress models for both the explicit (EARSM) and the more traditional or implicit (IARSM) forms. Results are generally very promising and of sufficient accuracy for engineering interest. Overall, the study indicates that for flows around low-speed high-lift airfoils, the algebraic Reynolds-stress construct does not represent a higher level of description than the eddy viscosity models since it fails to improve on accuracy. The basic underlying assumption of weak-equilibrium in algebraic Reynolds-stress models is outperformed by well calibrated eddy-viscosity models.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1996 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP. written by and published by . This book was released on 1992 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent and Separated Flow Over Multi-element Aerofoils by : Zaffar Mahmood
Download or read book Turbulent and Separated Flow Over Multi-element Aerofoils written by Zaffar Mahmood and published by . This book was released on 1995 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Analysis of Incompressible Visious Flow Over Single and Multi-element Airfoils by : Omer Ali El-Sayed
Download or read book Computational Analysis of Incompressible Visious Flow Over Single and Multi-element Airfoils written by Omer Ali El-Sayed and published by . This book was released on 2003 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow-field around a multi-element airfoil with leading-edge slat and trailing edge flap in landing configuration was performed as well as the prediction of the time dependent flow over a NACA 0012 airfoil. The two dimensional incompressible Navier-Stokes equations with a numerical method based on the pseudo compressibility approach was developed to simulate viscous turbulent flow around single and multi-element airfoils. The algorithm uses upwind-biased scheme of third order accuracy for the calculation of the inviscid fluxes, while a second order central differencing in sued for viscous fluxes, the equations are solved using Lower-Upper Symmetric Gauss Seidel (LU-SGS) schemes. The grids around multi-element airfoil are efficiently generated using a multi-block structure technique. The Baldwin-Lomax algebraic turbulence model is used to consider the effect of turbulence. Computed results for the studied cases were compared with experimental data in terms of surface pressure and lift coefficients which show reasonable agreement.
Download or read book Journal of Aircraft written by and published by . This book was released on 1999 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis American Doctoral Dissertations by :
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1995 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1993 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
Book Synopsis Aeronautical Engineering: A Cumulative Index to a Continuing Bibliography (supplement 261) by :
Download or read book Aeronautical Engineering: A Cumulative Index to a Continuing Bibliography (supplement 261) written by and published by . This book was released on 1991 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Recent Advances in Computational Methods to Solve the High-Lift Multi-Component Airfoil Problem by : B. Oskam
Download or read book Recent Advances in Computational Methods to Solve the High-Lift Multi-Component Airfoil Problem written by B. Oskam and published by . This book was released on 1984 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current research in the area of high-lift aerodynamics is directed towards development of a computational design capability for high-lift systems consisting of flaps and slats. The development of mathematical models to analyze viscous flow over high-lift multi-component airfoil configurations is the first phase in such a research program. This paper describes recent advances made in solving this high-lift multicomponent airfoil problem. Two particular aspects of the problem are addressed. The first aspect concerns the calculation of viscous wakes subjected to large adverse pressure gradients. This 'off-the-surface' pressure recovery is a flow feature unique to multi-component airfoils, and is not present in the single-component airfoil problem. The second aspect dealt with concerns the locally supersonic flow over the slat of a high-lift configuration, with a free stream Mach number of around 0.2. In this 'low speed' regime the highest local velocities are found to reach Mach numbers of around 1.6 indicating that in the final analysis of viscous flow over high-lift multi-component airfoil configurations it is imperative to include the nonlinear compressible flow effects.
Book Synopsis Computational Aerodynamics on Unstructed Meshes by : Yun Zheng
Download or read book Computational Aerodynamics on Unstructed Meshes written by Yun Zheng and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: New 2D and 3D unstructured-grid based flow solvers have been developed for simulating steady compressible flows for aerodynamic applications. The codes employ the full compressible Euler/Navier-Stokes equations. The Spalart-Al Imaras one equation turbulence model is used to model turbulence effects of flows. The spatial discretisation has been obtained using a cell-centred finite volume scheme on unstructured-grids, consisting of triangles in 2D and of tetrahedral and prismatic elements in 3D. The temporal discretisation has been obtained with an explicit multistage Runge-Kutta scheme. An "inflation" mesh generation technique is introduced to effectively reduce the difficulty in generating highly stretched 2D/3D viscous grids in regions near solid surfaces. The explicit flow method is accelerated by the use of a multigrid method with consideration of the high grid aspect ratio in viscous flow simulations. A solution mesh adaptation technique is incorporated to improve the overall accuracy of the 2D inviscid and viscous flow solutions. The 3D flow solvers are parallelised in a MIMD fashion aimed at a PC cluster system to reduce the computing time for aerodynamic applications. The numerical methods are first applied to several 2D inviscid flow cases, including subsonic flow in a bump channel, transonic flow around a NACA0012 airfoil and transonic flow around the RAE 2822 airfoil to validate the numerical algorithms. The rest of the 2D case studies concentrate on viscous flow simulations including laminar/turbulent flow over a flat plate, transonic turbulent flow over the RAE 2822 airfoil, and low speed turbulent flows in a turbine cascade with massive separations. The results are compared to experimental data to assess the accuracy of the method. The over resolved problem with mesh adaptation on viscous flow simulations is addressed with a two phase mesh reconstruction procedure. The solution convergence rate with the aspect ratio adaptive multigrid method and the direct connectivity based multigrid is assessed in several viscous turbulent flow simulations. Several 3D test cases are presented to validate the numerical algorithms for solving Euler/Navier-Stokes equations. Inviscid flow around the M6 wing airfoil is simulated on the tetrahedron based 3D flow solver with an upwind scheme and spatial second order finite volume method. The efficiency of the multigrid for inviscid flow simulations is examined. The efficiency of the parallelised 3D flow solver and the PC cluster system is assessed with simulations of the same case with different partitioning schemes. The present parallelised 3D flow solvers on the PC cluster system show satisfactory parallel computing performance. Turbulent flows over a flat plate are simulated with the tetrahedron based and prismatic based flow solver to validate the viscous term treatment. Next, simulation of turbulent flow over the M6 wing is carried out with the parallelised 3D flow solvers to demonstrate the overall accuracy of the algorithms and the efficiency of the multigrid method. The results show very good agreement with experimental data. A highly stretched and well-formed computational grid near the solid wall and wake regions is generated with the "inflation" method. The aspect ratio adaptive multigrid displayed a good acceleration rate. Finally, low speed flow around the NREL Phase 11 Wind turbine is simulated and the results are compared to the experimental data.
Book Synopsis The Structure and Behaviour of Laminar Separation Bubbles by : Michael Gaster
Download or read book The Structure and Behaviour of Laminar Separation Bubbles written by Michael Gaster and published by . This book was released on 1969 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Transition and Vortex Systems of a Dynamically Pitching Airfoil Under the Free-stream Turbulence Conditions by : Anurag Gandhi
Download or read book Investigation of Transition and Vortex Systems of a Dynamically Pitching Airfoil Under the Free-stream Turbulence Conditions written by Anurag Gandhi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of reduced frequency on dynamic stall behavior of a pitching NACA0012 airfoil in a turbulent wake using Direct Numerical Simulations is presented in the current study. Upstream turbulence with dynamically oscillating blades and airfoils is associated with ambient flow unsteadiness and is encountered in many operating conditions. Wake turbulence, a more realistic scenario for airfoils in operation, is generated using a small solid cylinder placed upstream, the vortices shed from which interact with the pitching airfoil affecting dynamic stall behavior. A recently developed moving overlapping grid approach is used using a high-order Spectral Element Method (SEM) for spatial discretization combined with a dynamic time-stepping procedure allowing for up to third order temporal discretization. Two cases of reduced frequency (k = 0:16 and 0:25) for airfoil oscillation are investigated and the change in dynamic stall behavior with change in reduced frequency is studied and documented using flow-fields and aerodynamic coefficients (Drag, Lift and Pitching Moment) with a focus on understanding vortex system dynamics (including formation of secondary vortices) for different reduced frequencies and it's affect on airfoil aerodynamic characteristics and fatigue life. Transition of the flow over the surface of an airfoil for both undisturbed and disturbed flow cases will also be discussed using Pressure coefficient and Skin Friction coefficient data for a given cycle combined with a wavelet analysis using Morse wavelets in MATLAB.
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1994 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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