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Numerical Investigation Of Static And Dynamic Stall Of Single And Flapped Airfoils
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Book Synopsis Numerical Investigation of Static and Dynamic Stall of Single and Flapped Airfoils by : Nicholas Dwayne Liggett
Download or read book Numerical Investigation of Static and Dynamic Stall of Single and Flapped Airfoils written by Nicholas Dwayne Liggett and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Separated flows about single and multi-element airfoils are featured in many scenarios of practical interest, including: stall of fixed wing aircraft, dynamic stall of rotorcraft blades, and stall of compressor and turbine elements within jet engines. In each case, static and/or dynamic stall can lead to losses in performance. More importantly, modeling and analysis tools for stalled flows are relatively poorly evolved and designs must completely avoid stall due to a lack of understanding. The underlying argument is that advancements are necessary to facilitate understanding of and applications involving static and dynamic stall.\r : \r : The state-of-the-art in modeling stall involves numerical solutions to the governing equations of fluids. These tools often either lack fidelity or are prohibitively expensive. Ever-increasing computational power will likely lead to increased application of numerical solutions. The focus of this thesis is improvements in numerical modeling of stall, the need of which arises from poorly evolved analysis tools and the spread of numerical approaches. Technical barriers have included ensuring unsteady flow field and vorticity reproduction, transition modeling, non-linear effects such as viscosity, and convergence of predictions.\r : \r : Contributions to static and dynamic stall analysis have been been made. A hybrid Reynolds-Averaged Navier-Stokes/Large-Eddy-Simulation turbulence technique was demonstrated to predict the unsteadiness and acoustics within a cavity with accuracy approaching Large-Eddy-Simulation. Practices to model separated flows were developed and applied to stalled airfoils. Convergence was characterized to allow computational resources to be focused only as needed. Techniques were established for estimation of integrated coefficients, onset of stall, and reattachment from unconverged data. Separation and stall onset were governed by turbulent transport, while the location of reattachment depended on the mean flow. Application of these methodologies to oscillating flapped airfoils revealed flow through the gap was dominated by the flap angle for low angles of attack. Lag between the aerodynamic response and input flap scheduling was associated with increased oscillation frequency and airfoil/flap gap size. Massively separated flow structures were also examined.
Book Synopsis Numerical Investigation of Airfoil Dynamic Stall in Simultaneous Harmonic Oscillatory and Translatory Motion by : John A. Ekaterinaris
Download or read book Numerical Investigation of Airfoil Dynamic Stall in Simultaneous Harmonic Oscillatory and Translatory Motion written by John A. Ekaterinaris and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Investigation of the Effect of Leading Edge Geometry on Dynamic Stall of Airfoils by :
Download or read book Numerical Investigation of the Effect of Leading Edge Geometry on Dynamic Stall of Airfoils written by and published by . This book was released on 1990 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic stall of rapidly pitching and oscillating airfoils is investigated by the numerical solution of the full compressible unsteady two- dimensional Navier-Stokes equations using an alternating-direction-implicit scheme. The flow is assumed to be fully turbulent, and the turbulent stresses are modelled by the Baldwin-Lomax eddy viscosity model. Three airfoils (NACA 0012, NACA 0012-33, and NACA 0012-63) are analyzed for the purpose of examining the influence of leading-edge geometry on unsteady flow separation. It is found that a larger leading edge radius, thicker contouring of the forward part of the airfoil, or increasing reduced frequency results in delaying flow separation and formation of the dynamic stall vortex to a higher angle of attack, yielding higher peak Cl. Within the scope of this study, the pressure gradient encountered by the flow at initial separation is found to be independent of reduced frequency and freestream speed. The critical pressure gradient is dependent on leading edge radius and increases for decreasing leading edge radius.
Book Synopsis Numerical Investigation of Airfoil Dynamic Stall in Simulatneous Harmonic Oscillatory and Translatory Motion by : J. A. Ekaterinaris
Download or read book Numerical Investigation of Airfoil Dynamic Stall in Simulatneous Harmonic Oscillatory and Translatory Motion written by J. A. Ekaterinaris and published by . This book was released on 1997 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental and Numerical Investigation of Airfoil Dynamic Stall in Combined Pitch-translation Oscillation by : Michel Pascazio
Download or read book Experimental and Numerical Investigation of Airfoil Dynamic Stall in Combined Pitch-translation Oscillation written by Michel Pascazio and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Experimental Study of Dynamic Stall on Advanced Airfoil Sections. Volume 1: Summary of the Experiment by :
Download or read book An Experimental Study of Dynamic Stall on Advanced Airfoil Sections. Volume 1: Summary of the Experiment written by and published by . This book was released on 1982 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The static and dynamic characteristics of seven helicopter sections and a fixed-wing supercritical airfoil were investigated over a wide range of nominally two-dimensional flow conditions, at Mach numbers up to 0.30 and Reynolds numbers up to 4x10 to the 6th power. Details of the experiment, estimates of measurement accuracy, and test conditions are described in this volume. The results of the experiment show important differences between airfoils, which would otherwise tend to be masked by differences in wind tunnels, particularly in steady cases. All of the airfoils tested provide significant advantages over the conventional NACA 0012 profile. In general, however, the parameters of the unsteady motion appear to be more important than airfoil shape in determining the dynamic-stall airloads.
Book Synopsis Experimental and numerical investigations of dynamic stall on a pitching airfoil by : P. Wernert
Download or read book Experimental and numerical investigations of dynamic stall on a pitching airfoil written by P. Wernert and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Suppression of Dynamic Stall with a Leading-edge Slat on a VR-7 Airfoil by : K. W. McAlister
Download or read book Suppression of Dynamic Stall with a Leading-edge Slat on a VR-7 Airfoil written by K. W. McAlister and published by . This book was released on 1993 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Adm Nasa Publisher :Independently Published ISBN 13 :9781723809088 Total Pages :64 pages Book Rating :4.8/5 (9 download)
Book Synopsis Airfoil Dynamic Stall and Rotorcraft Maneuverability by : National Aeronautics and Space Adm Nasa
Download or read book Airfoil Dynamic Stall and Rotorcraft Maneuverability written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-18 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to effects such as the airfoil section profile and Mach number, and appears to be independent of such parameters as Reynolds number, reduced frequency, and blade sweep. For single-element airfoils there is little that can be done to improve rotorcraft maneuverability except to provide good static C(l(max)) characteristics and the chord or blade number that is required to provide the necessary rotor thrust. However, multi-element airfoils or airfoils with variable geometry features can provide augmented lift in some cases that exceeds that available from a single-element airfoil. The dynamic stall function is shown to be a useful tool for the evaluation of both measured and calculated dynamic stall characteristics of single element, multi-element, and variable geometry airfoils.Bousman, William G.Ames Research CenterAERODYNAMIC STALLING; ROTARY WING AIRCRAFT; MANEUVERABILITY; VORTICES; AIRFOIL PROFILES; THRUST; LEADING EDGES; MACH NUMBER; PITCHING MOMENTS; REYNOLDS NUMBER; DRAG; AERODYNAMIC LOADS
Book Synopsis Numerical Investigation of Dynamic Stall of an Oscillating Wing by : John A. Ekaterinaris
Download or read book Numerical Investigation of Dynamic Stall of an Oscillating Wing written by John A. Ekaterinaris and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulation of Dynamic Stall of NACA0012 Airfoil Oscillating Near Static Stall Angle Using the Navier-Stokes Equations by :
Download or read book Numerical Simulation of Dynamic Stall of NACA0012 Airfoil Oscillating Near Static Stall Angle Using the Navier-Stokes Equations written by and published by . This book was released on 1992 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Numerical Investigation of Laminar Airfoil Stall by : Daniel Wayne Black
Download or read book A Numerical Investigation of Laminar Airfoil Stall written by Daniel Wayne Black and published by . This book was released on 1993 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of the Development of Dynamic Stall Based on Oscillating Airfoil Experiments by : Lawrence W. Carr
Download or read book Analysis of the Development of Dynamic Stall Based on Oscillating Airfoil Experiments written by Lawrence W. Carr and published by . This book was released on 1977 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Analysis of Airfoils with Gurney Flaps at Low Reynolds Number by : Valentin Roy
Download or read book Numerical Analysis of Airfoils with Gurney Flaps at Low Reynolds Number written by Valentin Roy and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "A two-dimensional numerical investigation was performed to determine the effect of a Gurney flap on symmetric and cambered airfoils at very low Reynolds number. A Gurney flap is a device consisting of a small tab attached at the trailing edge and perpendicular to the chord line of the airfoil. Originally installed on a race car wing, a Gurney flap was proven to have a positive influence on the lift to drag ratio, and leading therefore to better efficiency and performance. First studies of Gurney flap showed that the optimal length of such a device is in the order of 1-4% of the chord length. The increase in lift comes primarily from the increased effective camber of the airfoil without disturbing the upper surface flow. The flow field around the airfoil is numerically studied in this thesis using an efficient numerical analysis based on a pseudo-time integration method using artificial compressibility. Gurney flap of sizes ranging from 1 to 4% of the airfoil chord were studied. The numerical solutions show the pressure distribution along the airfoil and flap as well as the lift and drag coefficients. The streamline contours illustrating the flow separation regions have also been generated. The influence of the flap length and the angle of attack on the aerodynamic coefficients was thoroughly studied." --
Book Synopsis An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence by :
Download or read book An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence written by and published by DIANE Publishing. This book was released on 2003 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Low Reynolds Number by : Mustafa Serdar Genç
Download or read book Low Reynolds Number written by Mustafa Serdar Genç and published by BoD – Books on Demand. This book was released on 2012-04-04 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports the latest development and trends in the low Re number aerodynamics, transition from laminar to turbulence, unsteady low Reynolds number flows, experimental studies, numerical transition modelling, control of low Re number flows, and MAV wing aerodynamics. The contributors to each chapter are fluid mechanics and aerodynamics scientists and engineers with strong expertise in their respective fields. As a whole, the studies presented here reveal important new directions toward the realization of applications of MAV and wind turbine blades.
