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Simulations of Active Vortex GeneratorsWe are interested in the study, via numerical simulations, of active vortex generators. Vortex generators may be used to modify the inner part of the boundary layer or to control separation thus enhancing the performance and maneuverability of aerodynamic configurations. We consider generators that consist of a surface cavity elongated in the streamwise direction and partially covered with a moving lid that at rest lies flush with the boundary. Streamwise voracity is generated and ejected due to the oscillatory motion of the lid. The present simulations c Implement relevant experimental investigations of active vortex generators that have been conducted at NASA Ames Research Center and Stanford University. Jacobson and Reynolds used a piezoelectric device in water, allowing for small amplitude high frequency oscillations. They placed the lid asymmetrically on the cavity and observed a strong outward velocity at the small gap of the cavity. Saddoughi used a larger mechanically driven device in air to investigate this flow and observed a jet emerging from the wide gap of the configuration, contrary to the findings of Jacobson and Reynolds. More recently, Lachowiez and Wlezien are investigating the flow generated by an electro-mechanically driven lid to be used for assertion control in aerodynamic applications. We are simulating the flows generated by these devices and we are conducting a parametric study that would help us elucidate the physical mechanisms present in the flow. Conventional computational schemes encounter difficulties when simulating flows around complex configurations undergoing arbitrary motions. Here we present a formulation that achieves this task on a purely Lagrangian frame by extending the formulation presented by Koumoutsakos, Leonard and Pepin. The viscous effects are taken into account by modifying the strength of the particles, whereas fast multipole schemes employing hundreds of thousands ol'particle's allow for high resolution simulations. We shall present simulation results of an oscillating plate at various Reynolds numbers and Strouhal frequencies. Estimates of the forces needed to drive the devices will also be presented.
Document ID
20020042890
Acquisition Source
Ames Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Mansour, N. N.
(NASA Ames Research Center Moffett Field, CA United States)
Koumoutsakos, P.
(NASA Ames Research Center Moffett Field, CA United States)
Merriam, Marshal
Date Acquired
August 20, 2013
Publication Date
January 1, 1996
Subject Category
Fluid Mechanics And Thermodynamics
Funding Number(s)
PROJECT: RTOP 505-59-53
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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