Journal ArticleDOI
The Effect of Varying Freestream Velocity on Airfoil Dynamic Stall Characteristics
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This article is published in Journal of The American Helicopter Society.The article was published on 1978-04-01. It has received 22 citations till now. The article focuses on the topics: Freestream & Stall (engine).read more
Citations
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Journal ArticleDOI
Dynamic stall simulation of a pitching airfoil under unsteady freestream velocity
Kobra Gharali,David A. Johnson +1 more
TL;DR: In this paper, the effects of horizontal oscillations of the freestream velocity superimposed on a pitch oscillating NACA0012 airfoil were investigated using Computational Fluid Dynamics (CFD).
Journal ArticleDOI
Unsteady Low-Speed Wind Tunnels
TL;DR: In this article, a theory based upon linearized governing equations is developed that describes the operation principles and design parameters for low-speed wind tunnels with longitudinal freestream oscillations.
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Airfoil in a high amplitude oscillating stream
Christoph Strangfeld,Hanns Müller-Vahl,Christian Navid Nayeri,Christian Oliver Paschereit,David Greenblatt +4 more
TL;DR: In this paper, a combined theoretical and experimental investigation was carried out with the objective of evaluating theoretical predictions relating to a two-dimensional airfoil subjected to high amplitude harmonic oscillation of the free stream at constant angle of attack.
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Modification of Transonic Blowdown Wind Tunnel to Produce Oscillating Freestream Mach Number
TL;DR: In this article, a modification to the Transonic Wind Tunnel at Ohio State University was proposed to enable modulation of the freestream Mach number in a harmonic fashion, which can achieve Mach oscillations between 0.4 and 0.6 at a controlled frequency up to 25Hz and a Reynolds number range of 2 -16 million per foot.
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Vortex formation on surging aerofoils with application to reverse flow modelling
Philip B. Kirk,Anya R. Jones +1 more
TL;DR: In this paper, the leading-edge vortex (LEV) is a powerful unsteady flow structure that can result in significant unstiredy loads on lifting blades and wings, and the authors present an experimental campaign to characterize LEV behavior in sinusoidally surging flows with widely varying amplitudes and frequencies.
References
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General Theory of Aerodynamic Instability and the Mechanism of Flutter
TL;DR: In this paper, the Kutta condition was used to analyze the aerodynamic forces on an oscillating airfoil or an air-foil-aileron combination of three independent degrees of freedom.
Airfoil in sinusoidal motion in a pulsating stream
TL;DR: In this paper, the forces and moments on a two-dimensional airfoil executing harmonic motions in a pulsating stream are derived on the basis of non-stationary incompressible potential flow theory, with the inclusion of the effect of the continuous sheet of vortices shed from the trailing edge.
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Dynamic Stall Considerations in Helicopter Rotors
Norman D. Ham,Melvin S. Garelick +1 more
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Aerodynamic loading on a two-dimensional airfoil during dynamic stall.
TL;DR: In this article, a general theory for the unsteady aerodynamic loading on an airfoil during dynamic stall is developed, which is represented by the shedding of vorticity from the vicinity of the leading edge.
A correlation of low-speed, airfoil-section stalling characteristics with Reynolds number and airfoil geometry
TL;DR: In this article, the low-speed stalling characteristics of a large number of airfoil sections have been correlated with Reynolds number and a single ordinate near the leading edge as the correlation parameters.