Near-field development of large-scale vortical structures in a controlled confined coaxial jet

Mitsuishi, Akihiko; Fukagata, Koji; Kasagi, Nobuhide

doi:10.1080/14685240600871037

Cited by 15 publications

(9 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The coupling between the velocity and the pressure is done similarly to that in the SMAC method (Amsden and Harlow, 1970). The pressure Poisson equation is solved using the fast Fourier transform in the streamwise direction with the mirroring technique (Mitsuishi et al, 2007) and the tridiagonal matrix solver in the wall-normal direction.…”

Section: Methodsmentioning

confidence: 99%

Friction drag reduction of a spatially developing boundary layer using a combined uniform suction and blowing

Noguchi

Fukagata

Tokugawa

2016

JFST

Self Cite

View full text Add to dashboard Cite

Uniform suction or blowing from the wall is one of the methods to reduce the friction drag. The uniform suction improves the stability of a laminar boundary layer: the transition will be delayed and the overall friction drag will be reduced due to the extended laminar region. In contrast, the uniform blowing is known to reduce the drag in the fully-turbulent regime. Therefore, a combination of uniform suction and blowing is expected to be effective for flows involving transition, such as the flow around an airfoil, by delaying the transition near the trailing edge and by reducing the turbulent drag in the post-transition (i.e., turbulent) region. The objective of this study is to investigate the friction drag reduction effect of such a combined uniform suction and blowing. The ReynoldsAveraged Navier-Stokes simulation is used to deal with a spatially developing boundary layer on a flat plate at a practically high Reynolds number. As a result, the combined control is found to reduce the global skin friction coefficient by 44.1%, whereof the contribution of transition delay by the uniform suction is about 90%, and that of turbulent drag reduction by the uniform blowing is about 10%. It is also found that the position of the blowing region should better be located in the upstream side of the turbulent region because the drag reduction effect is sustained for a while even after the blowing is terminated.

show abstract

Section: Methodsmentioning

confidence: 99%

Friction drag reduction of a spatially developing boundary layer using a combined uniform suction and blowing

Noguchi

Fukagata

Tokugawa

2016

JFST

Self Cite

View full text Add to dashboard Cite

show abstract

“…The two-dimensional (i.e., spanwise and streamwise) fast Fourier transform with the mirror image (28) is used to solve the Poisson equation in the non-periodic geometry. The Cartesian structured grid is used and the no-slip boundary condition on the wing surface is treated by using the immersed boundary method.…”

Section: Computational Condition and Methodsmentioning

confidence: 99%

An Attempt for Suppression of Wing-Tip Vortex Using Plasma Actuators

Hasebe

Naka

Fukagata

2011

JFST

Self Cite

View full text Add to dashboard Cite

Influence of the flow induced by dielectric barrier discharge (DBD) plasma actuators on the wing-tip vortex is investigated numerically and experimentally. The plasma actuators are installed on the suction side of the NACA0012 airfoil and operated in blowing and suction modes. For the numerical simulation, direct numerical simulation (DNS) based on the finite-difference immersed-boundary method is used. The DNS shows that the circulation parameter, which measures the strength of wing-tip vortex, is reduced by blowing as well as suction. At the same time, however, the lift-to-drag ratio is found to decrease by the actuation. In the experiment, a wing model with plasma actuators is set inside the wind tunnel and the velocity fields are measured using a PIV system. Although suppression of wing-tip vortex is not confirmed due to insufficient strength of actuation and insufficient length of measurement area, the change of streamwise mean velocity profile is found to be similar to that of DNS.

show abstract

“…These are introduced by letting the flow pass through glass vessels containing particles before entering the jet chamber. The relaxation time of the particles [20] is about 1 µs, which is much smaller than the Kolmogorov time scale, if estimated as D 2 0 Re −3/2 /ν = 227 µs. Therefore, we can assume that the particles perfectly follow the flow.…”

Section: Piv Setupmentioning

confidence: 99%

Evolution of the streamwise vortices in a coaxial jet controlled with micro flap actuators

Angele

Kurimoto

Suzuki

et al. 2006

Journal of Turbulence

View full text Add to dashboard Cite

A coaxial jet was actively controlled by a MEMS-fabricated micro flap actuator nozzle. The effect of different control modes on secondary azimuthal instabilities and the evolution of streamwise vortices were investigated by applying stereoscopic PIV to the cross-stream plane of the jet. Forcing with non-symmetric modes, in particular the least-stable helical mode, accelerates the evolution of the streamwise vortices through the enhancement of azimuthal instabilities. Although forcing is applied to the outer shear layer of the outer jet, the control effect is most pronounced in the inner shear layer of the inner jet. Unlike in the natural jet, streamwise vortices appear in the inner shear layer of the controlled jet. For forcing with the fundamental axisymmetric mode, a Strouhal number of the order of unity maximise the azimuthal instabilities and hence the counts of the streamwise vortices. The present result is in accordance with our previous experimental findings in the longitudinal plane, where the evolution of the primary vortices and mixing between the inner and the outer jets were examined through 2D-PIV and PLIF (Kurimoto et al., 2004, Active control of coaxial jet mixing with arrayed micro actuators. Transactions of the Japanese Society of Mechanical Engineers, This emphasises the connection between primary and streamwise vortices and their significance in the mixing enhancement process. It is also found that the azimuthal wavelength under the present control scheme is almost the same as that of the natural jet and independent of the streamwise position.

show abstract

Near-field development of large-scale vortical structures in a controlled confined coaxial jet

Cited by 15 publications

References 19 publications

Friction drag reduction of a spatially developing boundary layer using a combined uniform suction and blowing

Friction drag reduction of a spatially developing boundary layer using a combined uniform suction and blowing

An Attempt for Suppression of Wing-Tip Vortex Using Plasma Actuators

Evolution of the streamwise vortices in a coaxial jet controlled with micro flap actuators

Contact Info

Product

Resources

About