Strong vortex/boundary layer interactions

Cutler, Andrew D.; Bradshaw, P.

doi:10.1007/bf00190193

Cited by 32 publications

(8 citation statements)

References 9 publications

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“…This is probably due to the interaction of the longitudinal vortices and the wall boundary layer, generating lateral shear. 29 The presence of the vortices over the surface of the modified foils at large attack angles dramatically impacts the induced velocity field. The pseudo-streamlines colored by velocity, in Figure 28, demonstrate that the induced velocity of the dominant primary vortices of the long separation bubbles transports high momentum flow towards the central trough region, leading to attached flow.…”

Section: Detailed Flow Structure Analysis: Post-stallmentioning

confidence: 99%

The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

Rostamzadeh¹,

Hansen²,

Kelso³

et al. 2014

Physics of Fluids

123

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A direct numerical simulation investigation of the synthetic jet frequency effects on separation control of low-Re flow past an airfoil A two-dimensional numerical study is performed to investigate the relation between the direction of a deflected wake and the vortex pairing mechanisms. The deflection angle can be correlated with two effective phase velocities defined to represent the trends of symmetry breaking and symmetry holding, respectively. The deflection angle increases with the strength of the vortex pairs, which is associated with the heaving amplitude, frequency, and the free stream Reynolds number. Furthermore, not only the influence of Strouhal number but also those of the two heaving motion components-amplitude and frequency-are studied individually under different Reynolds numbers. The study shows that the deflection angle consistently increases with the difference between the symmetry-breaking phase velocity and symmetry-holding phase velocity. C 2012 American Institute of Physics. [http://dx.

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Section: Detailed Flow Structure Analysis: Post-stallmentioning

confidence: 99%

The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

Rostamzadeh¹,

Hansen²,

Kelso³

et al. 2014

Physics of Fluids

123

View full text Add to dashboard Cite

show abstract

“…The interaction involves turbulent, momentum-deficient fluid to entrain from the boundary layer into the vortex and causes a decay and an increase of the circulation of the pressure and suction side branches due to the opposite and same vorticity sign relative to the boundary layer flow, respectively (see, e.g., Cutler & Bradshaw 1993;Muscari et al 2017). As a result of the vortex-boundary layer interaction either the two vortex branches break into two smaller filaments that, in turn, keep wrapping around the leading edge of the wing, whereas detach from the body (suction and pressure side filaments 1 in figure 17) and move downstream with the main flow (suction and pressure side filaments 2 in figure 17).…”

Section: Vortex Penetration Phasementioning

confidence: 99%

Underlying mechanisms of propeller wake interaction with a wing

Felli

2020

J. Fluid Mech.

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“…As the vortex was positioned closer to the surface, viscous effects became important and vortex breakdown and boundary-layer separation occured, leading to large discrepancies between the theory and experiment. Cutler and Bradshaw [15,16] …”

Section: Introductionmentioning

confidence: 98%

Numerical Simulation of the Impingement of a Streamwise Vortex on a Plate

Gordnier

Visbal

1999

International Journal of Computational Fluid Dynamics

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The now field generated by the impingement of a delta-wing vortex on a plate is examined computationally. The now is simulated by solving the unsteady, threedimensional Navier-Stokes equations on an overset grid system using a time accurate, implicit Beam and Warming algorithm. Comparison of the computed solutions for two levels of mesh resolution indicates that no additional now features appear with grid refinement. Both the mean and unsteady now structures are examined. Over the delta wing the now exhibits a spiral vortex breakdown induced by the plate. Underneath the plate a highly unsteady, large-scale (owl-type) stall region is formed and results in the shedding of hairpin-like vortieal structures. On the top surface of the plate a shallow separation region also exists outboard of the vortex impingement location. These separated now features result from the spanwise variation in effective angle of attack created by the incoming vortex system. Also present over the upper surface is a mean longitudinal vortical structure arising from the passage of segments of the spiral filament. The frequency of the surface pressure fluctuations at a point on the plate leading edge that corresponds to the spiral mode of breakdown is found to be in agreement with experimental measurements. The mutual interaction between the breakdown and the stalled now is explored. A pronounced sensitivity of breakdown location to the degree of obstruetion created by the plate separation is found. This feedback elTeet might suggest possible now control strategies.

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Strong vortex/boundary layer interactions

Cited by 32 publications

References 9 publications

The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's performance with undulating leading edge modification

Underlying mechanisms of propeller wake interaction with a wing

Numerical Simulation of the Impingement of a Streamwise Vortex on a Plate

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