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Flow Visualization Of Dynamic Stall On An Oscillating Airfoil
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Book Synopsis Flow Visualization of Dynamic Stall on an Oscillating Airfoil by : Bruce E. Brydges
Download or read book Flow Visualization of Dynamic Stall on an Oscillating Airfoil written by Bruce E. Brydges and published by . This book was released on 1989 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stroboscopic schlieren photography was used to investigate the effects of compressibility, reduced frequency, and amplitude on the dynamic stall of a NACA 0012 airfoil subjected to sinusoidal oscillation. The Mach number was varied from M at infinity = 0.25 to M at infinity = 0.45 (corresponding to a Reynolds number variation of Re = 450,000 to Re = 810,000); the reduced frequency was varied from k = 0.025 to k = 0.10. Oscillation amplitudes of alpha sub m = 5 deg and alpha sub m = 10 deg were compared. Schlieren photographs are presented, which document the dynamic stall vortex formation, convection, and shedding sequence for various experimental conditions. Additionally, a preliminary examination of the flow reattachment process was conducted. Data derived from the photographs indicates that increasing the compressibility causes dynamic stall to occur at lower angles of attack; while, increasing the reduced frequency and/or the oscillation amplitude effectively delays dynamic stall effects to a higher angle of attack. Flow reattachment is sensitive to both Mach number and reduced frequency for low values of these parameters; when either the Mach number or reduced frequency is sufficiently high, the reattachment process stabilizes. Keywords: Dynamic stall; Dynamic lift; Unsteady lift; Helicopter retreating blade stall; Oscillating airfoil; Flow visualization; Schlieren method. Theses. (jhd).
Book Synopsis Flow Visualization of Dynamic Stall on an Oscillating Airfoil by :
Download or read book Flow Visualization of Dynamic Stall on an Oscillating Airfoil written by and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stroboscopic schlieren photography was used to investigate the effects of compressibility, reduced frequency, and amplitude on the dynamic stall of a NACA 0012 airfoil subjected to sinusoidal oscillation. The Mach number was varied from M at infinity = 0.25 to M at infinity = 0.45 (corresponding to a Reynolds number variation of Re = 450,000 to Re = 810,000); the reduced frequency was varied from k = 0.025 to k = 0.10. Oscillation amplitudes of alpha sub m = 5 deg and alpha sub m = 10 deg were compared. Schlieren photographs are presented, which document the dynamic stall vortex formation, convection, and shedding sequence for various experimental conditions. Additionally, a preliminary examination of the flow reattachment process was conducted. Data derived from the photographs indicates that increasing the compressibility causes dynamic stall to occur at lower angles of attack; while, increasing the reduced frequency and/or the oscillation amplitude effectively delays dynamic stall effects to a higher angle of attack. Flow reattachment is sensitive to both Mach number and reduced frequency for low values of these parameters; when either the Mach number or reduced frequency is sufficiently high, the reattachment process stabilizes. Keywords: Dynamic stall; Dynamic lift; Unsteady lift; Helicopter retreating blade stall; Oscillating airfoil; Flow visualization; Schlieren method. Theses. (jhd).
Book Synopsis Flow Visualization Studies of the Mach Number Effects on the Dynamic Stall of an Oscillating Airfoil by : M. Chandrasekhara
Download or read book Flow Visualization Studies of the Mach Number Effects on the Dynamic Stall of an Oscillating Airfoil written by M. Chandrasekhara and published by . This book was released on 1989 with total page 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 Flow Visualization of Dynamic Stall on a Pitching Airfoil by : K.F. Tchon
Download or read book Flow Visualization of Dynamic Stall on a Pitching Airfoil written by K.F. Tchon and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Unsteady Aerodynamics of Airfoil Oscillating in and Out of Dynamic Stall by : C. M. Wang
Download or read book Unsteady Aerodynamics of Airfoil Oscillating in and Out of Dynamic Stall written by C. M. Wang and published by . This book was released on 1985 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: A solution procedure is presented for the computation of dynamic stall phenomena encountered by arbitrary shaped airfoils under arbitrary flow conditions. This procedure solves the unsteady, incompressible Navier-Stokes and the unsteady boundary layer equations using an efficient, zonal approach. A number of results for a modified NACA 0012 airfoil experiencing dynamic stall are presented and compared with available numerical data. Qualitative comparisons with flow visualization experiments are also presented. (Author).
Book Synopsis Water-tunnel Experiments on an Oscillating Airfoil at RE by : Kenneth W. McAlister
Download or read book Water-tunnel Experiments on an Oscillating Airfoil at RE written by Kenneth W. McAlister and published by . This book was released on 1978 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reattachment Studies of an Oscillating Airfoil Dynamic Stall Flow Field by : S. Ahmed
Download or read book Reattachment Studies of an Oscillating Airfoil Dynamic Stall Flow Field written by S. Ahmed and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effects of Motion History on Leading Edge Separation for an Airfoil Pitching to Large Angles of Attack by : Todd Allen Brown
Download or read book Effects of Motion History on Leading Edge Separation for an Airfoil Pitching to Large Angles of Attack written by Todd Allen Brown and published by . This book was released on 1992 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamic Stall Analysis Utilizing Interactive Computer Graphics by : Eric L. Pagenkopf
Download or read book Dynamic Stall Analysis Utilizing Interactive Computer Graphics written by Eric L. Pagenkopf and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Navier-Stokes problem solver, developed by L.N. Sankar, is modified to provide dynamic, interactive graphical presentations of predicted flow field solutions about a NACA-0012 airfoil section oscillating in pitch, in order to demonstrate the capabilities of dynamic graphics applications in the study of complex, unsteady flows. Flow field solutions in the form of pressure coefficient and stream function contour plots about an airfoil experiencing dynamic stall are plotted utilizing an IRIS 3000-series workstation and Graphical Animation System (GAS) software, developed by Sterling Software for NASA. These full cycle solutions in conjunction with dynamic surface pressure distribution plots and integrated lift, pitching moment and full cycle solutions, in conjunction with dynamic surface pressure distribution plots and integrated lift, pitching moment and drag coefficient data, are compared to existing experimental data in order to provide an indication of the validity of the code's far-field solution. Full procedural documentation is maintained in order to provide an efficient analysis tool for use in future oscillating airfoil studies planned by the NASA-Ames Fluid Mechanics Laboratory and the Naval Postgraduate School Department of Aeronautics and Astronautics. Keywords: Dynamic stall, Computer graphics, IRIS, Flow visualization, Theses. (jes).
Book Synopsis A Computational and Experimental Investigation of the Propulsive and Lifting Characteristics of Oscillating Airfoils and Airfoil Combinations in Incompressible Flow by : Kerry S. Neace
Download or read book A Computational and Experimental Investigation of the Propulsive and Lifting Characteristics of Oscillating Airfoils and Airfoil Combinations in Incompressible Flow written by Kerry S. Neace and published by . This book was released on 1992 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamic Stall on Airfoils in Oscillating Flow by : John Joseph Zolan
Download or read book Dynamic Stall on Airfoils in Oscillating Flow written by John Joseph Zolan and published by . This book was released on 1976 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis PIV-based Examination of Dynamic Stall on an Oscillating Airfoil by : Daniel E. Fredberg
Download or read book PIV-based Examination of Dynamic Stall on an Oscillating Airfoil written by Daniel E. Fredberg and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Schlieren Studies of Compressibility Effects on Dynamic Stall of Transiently Pitching Airfoils by :
Download or read book Schlieren Studies of Compressibility Effects on Dynamic Stall of Transiently Pitching Airfoils written by and published by . This book was released on 1993 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressibility effects on the flowfield of an airfoil executing rapid transient pitching motion from 0-60 deg over a wide range of Mach numbers and pitching rates were studied using a stroboscopic schlieren flow visualization technique. The studies have led to the first direct experimental documentation of multiple shocks on the airfoil upper surface flow for certain conditions. Also, at low Mach numbers, additional coherent vortical structures were found to be present along with the dynamic stall vortex, whereas at higher Mach numbers the flow was dominated by a single vortex. The delineating Mach number for significant compressibility effects was 0.3 and the dynamic stall process was accelerated by increasing the Mach number above that value. Increasing the pitch rate monotonically delayed stall to angles of attack as large as 27 deg.
Book Synopsis Leading Edge Velocity Field of an Oscillating Airfoil in Compressible Dynamic Stall by : R. D. VanDyken
Download or read book Leading Edge Velocity Field of an Oscillating Airfoil in Compressible Dynamic Stall written by R. D. VanDyken and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Velocity and Vorticity Distributions Over an Oscillating Airfoil Under Compressible Dynamic Stall by :
Download or read book Velocity and Vorticity Distributions Over an Oscillating Airfoil Under Compressible Dynamic Stall written by and published by . This book was released on 1993 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The velocity and vorticity fields around an oscillating airfoil in compressible dynamic stall are reported. Phase averaged, two component laser velocimetry data were obtained at a freestream Mach number of 0.3 and a reduced frequency of 0.05. This is the first set of velocity data available at a high Reynolds number (540,000) under compressible flow conditions and it serves as a good database for development and validation of computer codes. Of particular interest is the formation of a separation bubble, which bursts coincidently with the formation of the dynamic stall vortex, adding an extra degree of physical complexity to the problem.
Book Synopsis Characterization of Dynamic Stall on 9-15 % Thick Airfoils Using Experiment and Computation by : Phillip B. Davidson
Download or read book Characterization of Dynamic Stall on 9-15 % Thick Airfoils Using Experiment and Computation written by Phillip B. Davidson and published by . This book was released on 2014 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the blade geometry on wind turbines and helicopters has been optimized for a particular span location. Unsteady flow phenomena like dynamic stall limit these designs and need to be better understood and correctly simulated. Currently, empirical and computational fluid dynamics (CFD) methods are used to simulate rotating wind turbine or helicopter blades, but each of these methods has limitations in predicting unsteady separated flows. To address these needs, the present work investigated oscillating airfoils over a range of conditions with an approach that provided fast, low-cost unsteady pressure data combined with a highly resolved flow field to better understand the physics of dynamic stall. An additional objective was to show how such data may be used to assess CFD simulations. This research has yielded interesting results showing characteristics of thin airfoil stall, leading edge stall, and trailing edge stall that were sorted and classified. Classification of the oscillating airfoil behavior with or without dynamic stall was performed using previous definitions for stall regime, separation characteristics, and other qualitative differences in stall pattern. After classifying the unsteady flow for each of the cases, comparison of experimental results and results obtained using an unsteady Reynolds Averaged Navier-Stokes (URANS) solver was performed to assess the ability of the solver to produce the same unsteady effects. Although both experiment and computation produced similar flow features, the timing and magnitude of the features in the dynamic stall and re-attachment process of the pitching cycle exhibited some significant differences.
