Journal ArticleDOI
Influence of ZNMF jet flow control on the spatio-temporal flow structure over a NACA-0015 airfoil
TLDR
In this article, the spatio-temporal flow structure associated with zero-net-mass-flux (ZNMF) jet forcing at the leading edge of a NACA-0015 airfoil was investigated using high-repetition rate particle image velocimetry.Abstract:
The spatio-temporal flow structure associated with zero-net-mass-flux (ZNMF) jet forcing at the leading edge of a NACA-0015 airfoil (Re = 3 × 104) is investigated using high-repetition rate particle image velocimetry. Measurements are performed at an angle of attack of 18°, where in the absence of forcing, flow separation occurs at the leading edge. Forcing is applied at a frequency of f
+ = 1.3 and a momentum coefficient c
μ = 0.0014 for which previous force measurements indicated a 45 % increase in lift over the unforced case. The structure and dynamics associated with both the forced and unforced case are considered. The dominant frequencies associated with separation in the unforced case are identified with the first harmonic of the bluff body shedding f
wake closely corresponding to the forcing frequency of f
+ = 1.3. A triple-decomposition of the velocity field is performed to identify the spatio-temporal perturbations produced by the ZNMF jet forcing. This forcing results in a reattachment of the flow, which is caused by the generation of large-scale vortices that entrain high-momentum fluid from the freestream. Forcing at 2f
wake produces a series of vortices that advect parallel to the airfoil surface at a speed lower than the freestream velocity. Potential mechanisms by which these vortices affect flow reattachment are discussed.read more
Citations
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Droplet impact on superhydrophobic surfaces: A review of recent developments
TL;DR: In this paper, a brief review of potential applications of superhydrophobic surfaces is presented, which thoroughly focuses on the most recent advances regarding dynamics and kinematics of drop impinging super-hydrophilic substrates.
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Mechanisms for laminar separated-flow control using dielectric-barrier-discharge plasma actuator at low Reynolds number
Makoto Sato,Taku Nonomura,Koichi Okada,Kengo Asada,Hikaru Aono,Aiko Yakeno,Yoshiaki Abe,Kozo Fujii +7 more
TL;DR: In this article, a dielectric barrier discharge plasma actuator at a low Reynolds number is used for separation control of a NACA 0015 airfoil at a Reynolds number of 63,000.
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Experimental and numerical investigation of the primary breakup of an airblasted liquid sheet
K. Warncke,Sebastian Gepperth,B. Sauer,Amsini Sadiki,Johannes Janicka,Rainer Koch,Hans-Jörg Bauer +6 more
TL;DR: In this article, a single operating point of a planar prefilming airblast atomizer is investigated, based on a spatial resolution of 10µm and a consistent analysis of the liquid film in both the experimental and the numerical studies.
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A laboratory study on sediment resuspension within arrays of rigid cylinders
Rafael O. Tinoco,Giovanni Coco +1 more
TL;DR: In this paper, the authors present results from laboratory experiments on flow through submerged arrays of rigid cylinders embedded in a sandy bed, using rigid, cylindrical elements to mimic vegetation and benthos, to account for only the physical effects resulting from their presence, eliminating biological factors, such as biofilms and root systems.
Journal ArticleDOI
A direct numerical simulation investigation of the synthetic jet frequency effects on separation control of low-Re flow past an airfoil
Wei Zhang,Ravi Samtaney +1 more
TL;DR: In this paper, the authors present results of direct numerical simulations of a synthetic jet (SJ) based separation control of flow past a NACA-0018 (National Advisory Committee for Aeronautics) airfoil, at 10° angle of attack and Reynolds number 104 based on the air-foil chord length C and uniform inflow velocity U0.
References
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Journal ArticleDOI
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DissertationDOI
On the development of turbulent wakes from vortex streets
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Journal ArticleDOI
The control of flow separation by periodic excitation
TL;DR: In this article, a review of the control of flow separation from solid surfaces by periodic excitation is presented, with an emphasis on experimentation relating to hydrodynamic excitation, although acoustic methods as well as traditional boundary layer control, such as steady blowing and suction are discussed in order to provide an appropriate historical context for recent developments.