Results 211 to 220 of about 4,278 (263)

Starting vortex and lift on an airfoil

Physics of Fluids A: Fluid Dynamics, 1993
Consider an airfoil which is impulsively started from rest to a constant speed relative to an otherwise quiescent fluid at an angle of attack. The paper attempts to propose a precise definition for the ‘‘starting vortex’’ in viscous flow and investigate how an airfoil gains its lift through the starting vortex.
Chang, Chien-Cheng, Hsiau, Ying-Chien, Chu, Chin-Chou   +2 more
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Hybrid vortex method for lifting surfaces with free-vortex flow

18th Aerospace Sciences Meeting, 1980
A Nonlinear Hybrid Vortex method (NHV-method) has been developed for predicting the aerodynamic characteristics of wings exhibiting leading- and side-edge separations. This method alleviates the drawbacks of the Nonlinear Discrete Vortex method (NDV-method, also known as the multiple line vortex method.) The NHV-method combines continuous-vorticity and
O. KANDIL, L.-C. CHU, E. YATES, JR.
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Analytical prediction of vortex lift

17th Aerospace Sciences Meeting, 1979
General integral expressions are derived for the nonlinear lift and pitching moment of arbitrary wing planforms in subsonic flow. The analysis uses the suction analogy and an assumed pressure distribution based on classical linear theory results.
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Lift-induced vortex dipole collapse

Physical Review Fluids, 2017
Effects of buoyancy on fluid flow are studied through its action on countersigned light-cored vortex dipoles. Buoyant vortices can be modeled as spinning bodies experiencing a lift force. Theory and simulations show that buoyant vortex dipoles can annihilate, leading to large increases of enstrophy and kinetic energy.
S. Ravichandran, Harish N. Dixit, Rama Govindarajan   +2 more
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Interaction of a turbulent vortex with a lifting surface

23rd Aerospace Sciences Meeting, 1985
The impulsive noise due to blade-vortex-interaction is analyzing in the time domain for the extreme case when the blade cuts through the center of the vortex core with the assumptions of no distortion of the vortex path or of the vortex core. An analytical turbulent vortex core model, described in terms of the tip aerodynamic parameters, is used and ...
D. LEE, L. ROBERTS
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Application of Unsteady Vortex Lift in Turbomachinery

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2012
The Weis-Fogh mechansim is quite attractive because it can generate very high unsteady lift. It is indicated that the high unsteady lift is related to the attached vortex around the leading edge and trailing edge of wing/airfoil, which is caused by the relative motion.
Lin Du, Xiaofeng Sun, Vigor Yang
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Lift enhancement by an externally trapped vortex

10th Fluid and Plasmadynamics Conference, 1977
A theoretical study is made of the performance capabilities of a lift concept that utilizes a spanwise vortex over the upper surface of the wing. The vortex is generated by a vertical flap near the leading edge of the wing and maintained by suction through orifices in endplates at the wingtip.
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Augmentation of Vortex Lift by Spanwise Blowing

Journal of Aircraft, 1975
An investigation has been conducted to evaluate the aerodynamic effects associated with blowing a jet spanwise over a wing's upper surface in a direction parallel to the leading edge. Experimental pressure and force data were obtained on wings with sweep angles of 30 and 45 degrees and showed that spanwise blowing aids in the formation and control of ...
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Vortex wakes behind high-lift wings

Journal of Aircraft, 1971
At high wing lift coefficients pertinent to STOL operation, the conventional neglect of vortex roll-up effects can lead to errors when calculating downwash at the tail plane and in the presence of ground or wind-tunnel walls. A classical unsteady treatment in the cross-flow plane, which calculates the roll-up of an initial spanwise row of point ...
J. E. HACKETT, M. R. EVANS
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Some Ideas of Vortex Lift

SAE Technical Paper Series, 1975
<div class="htmlview paragraph">In tests on a glider designed for experimenting with vortex generated lift, the author experienced an unknown phenomenon which kept the glider afloat at half the usual sink rate and stalling speed. After study it was realized that a huge vortex had been forming after the stall which explained the presence of ...
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