Analysis of a turbulent jet mixing flow by using a PIV-PLIF combined system

Hu, Hengshan; Saga, Tsuneo; Kobayashi, Toshio; Taniguchi, Nobuyuki

doi:10.1007/bf03181483

Cited by 13 publications

(4 citation statements)

References 14 publications

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“…In the present study, a calibration experiment was conducted to confirm the linear relationship between the collected LIF signal and the concentration of the seeded Rhodamine B molecules. Following the similar procedure as described by Hu et al (19) and Posner & Santiago (14) , the effects of the non-uniformity of the illumination intensity, background noise, and the dark current of the CCD camera were corrected in the present study in order to minimize the measurement errors in the determination of scalar concentration distributions to quantify the scalar mixing process. In the present study, the size of the field of view is about 0.6 mm by 2.0mm with the spatial resolution of the acquired LIF images about 1.45 µm/pixel.…”

Section: Methodsmentioning

confidence: 99%

Fluid Mixing Control Inside a Y-shaped Microchannel by Using Electrokinetic Instability

Jin

Dawoud

et al. 2008

JFST

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A parametric study was conducted to improve our understanding pertaining to the fundamental physics of electrokinetic instability (EKI) and to explore the effectiveness of manipulating EKI waves to control/enhance fluid mixing inside a Y-shaped microchannel. The dependence of the critical strength of the applied static electric field to trigger the EKI waves on the conductivity ratio of the two mixing streams inside the Y-shaped microchannel was quantified at first. The effects of the applied electric field strength on the evolution of the EKI waves and the resultant fluid mixing were assessed in terms of scalar concentration distributions, shedding frequency of the EKI waves and fluid mixing efficiency. The effectiveness of manipulating the EKI waves by adding alternative perturbations to the applied static electric fields were also explored for the further enhancement of the fluid mixing inside the Y-shaped microchannel. The measurement results revealed that the relationship between the critical strength of the applied static electric field and the conductivity ratio of the two mixing streams in the Y-shaped microchannel can be represented well by a power function with the power index about -0.246. The fluid mixing efficiency was found to increase monotonically with the increasing strength of the applied electric field. The fluid mixing process was found to be further enhanced by adding alternative perturbations to the applied static electric fields with the mixing process being most enhanced when the frequency of the alternative perturbation is close to the natural shedding frequency of the EKI waves. The fluid mixing efficiency was found to increase rapidly as the amplitude of the alternative perturbation increases.

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Section: Methodsmentioning

confidence: 99%

Fluid Mixing Control Inside a Y-shaped Microchannel by Using Electrokinetic Instability

Jin

Dawoud

et al. 2008

JFST

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“…Each tab generates local shear resulting in a pair of counter rotating streamwise structures which are improving mixing. The lobed nozzle is another efficient mixing device (Belovich and Samimy, 1997;Yuan, 2000;Hu et al, 2000Hu et al, , 2001Hu et al, , 2002Hu et al, and 2004. Each lobe is the location of a pair of large scale streamwise structures having the size of the lobe.…”

Section: Introductionmentioning

confidence: 99%

Vortex dynamics and entrainment mechanisms in low Reynolds orifice jets

Năstase

Meslem

2008

J Vis

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Classical planar 2D-PIV measurements and time-resolved visualizations enriched by low-level processing are used for the reconstruction of the Kelvin-Helmholtz vortex passing in the near field of a circular and a 6-lobed orifice jet flow. In the circular jet, the entrainment is produced in the braid region, being interrupted in the presence of the Kelvin-Helmholtz ring. The latter compresses the streamwise vortices and alters their self-induction role. Conversely, the 6-lobed orifice geometry allows the cutting of the Kelvin-Helmholtz structures into discontinuous ring segments. Consequently, into these discontinuity regions streamwise large scale structures are developing. These streamwise structures are permanent thus controlling and enhancing the jet entrainment which is not altered by the Kelvin-Helmholtz structures passing.

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“…In his review article, Dimotakis (2000) discusses the mixing transition that seems to occur at Taylor's Reynolds number of order 100-140. Hu et al (2003) present simultaneous particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements in the near-nozzle region of a well-engineered jet, essentially duplicating and complementing the work of Yule (1978). Westerweel et al (2002Westerweel et al ( , 2005Westerweel et al ( , 2009 have presented details of the interface of a homogeneous turbulent water jet of initial diameter d = 1 mm at Re = 2000.…”

mentioning

confidence: 99%