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Van Buren T.,Rensselaer Polytechnic Institute | Amitay M.,Rensselaer Polytechnic Institute | Amitay M.,Center for Flow Physics and Control | Whalen E.,Boeing Company
50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2012

The effects of different geometries and input parameters on the flow structures of a finite span synthetic jet are explored in quiescent flow experiments using stereoscopic PIV. Common geometrical parameters, such as neck height, and orifice aspect ratio are varied along with the jet performance characteristics such as Strouhal numbers and Reynolds numbers. Orifice neck heights of 2, 4 and 6mm were tested at aspect ratios of 6, 12, and 18. Jet Strouhal numbers of 0.115 to 0.157 were tested at Reynolds numbers of 615. It is found that as the aspect ratio was increased the size of the vortical structures decreases, the vorticity dissipation rate increases, and axis switching occurred farther away from the orifice. The neck length had a large effect on the structures' size and strength, their dissipation rate, and the jet's spreading. Moreover, the driving frequency was found to affect the vortical structures spreading due to the streamwise spacing between structures, as well as drastically affecting dissipation of the structures in both planes. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. Source


Vasile J.D.,Rensselaer Polytechnic Institute | Amitay M.,Rensselaer Polytechnic Institute | Amitay M.,Center for Flow Physics and Control
52nd Aerospace Sciences Meeting | Year: 2014

An experimental investigation was performed to study the three-dimensional flow interaction of a finite-span synthetic jet located near the tip of a sweptback wing (crosssectional profile of the NACA 4421, AR = 4, sweep angle of 30°), at a Reynolds number of 105 and at three angles of attack of 0°, 9° and 15.5° (covering the range of attached to separated flow in the vicinity of the jet). Three blowing ratios were considered, 0.8, 1.2 and 2. Stereoscopic Particle Image Velocimetry (SPIV) data were collected at multiple 2-D planes in the vicinity of the jet’s orifice, which were then used to reconstruct the flow volume. The effect of the jet’s blowing ratio was analyzed using time-averaged and phase-averaged statistics. The study showed that the flow field in the vicinity of the synthetic-jet orifice becomes highly three-dimensional and is governed by the streamwise structures that are associated with the finite span of the orifice (edge vortices). The presence of a wing tip vortex results in the development of a non-uniform (in the spanwise direction) spanwise boundary layer that becomes more pronounced with increasing angle of attack. Consequently, the development of the jet and the associated flow structures are altered. © 2014, American Institute of Aeronautics and Astronautics Inc. All rights reserved. Source


Duffin D.A.,University of Notre Dame | Duffin D.A.,Center for Flow Physics and Control | Jumper E.J.,University of Notre Dame | Jumper E.J.,Center for Flow Physics and Control
AIAA Journal | Year: 2011

A feedforward adaptive-optic correction was made on a known, repeatable aero-optical aberration caused by a two-dimensional heated jet. Since the bandwidth requirements for traditional closed-loop adaptive-optic correction are significantly higher than current technology limitations, an unconventional feedforward adaptive-optic correction scheme was experimentally tested to determine the feasibility of adaptive-optic corrections for aerooptical disturbances in general. The feedforward adaptive-optic approach was successful in correcting aero-optical disturbances at a frequency of 240 Hz, as evidenced through Shack.Hartmann wave front sensor measurements. The feedforward correction scheme exceeded simulated performance predictions when it was able to boost the timeaveraged Strehl ratio from 0.64 without correction to 0.88 with correction. © 2011 by D. Duffin and E. Jumper. Source

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