The Kármán Vortex Street - LDV and PIV Measurements Compared with CFD

Pust, O.; Lund, C.M.

doi:10.1007/978-3-642-56963-0_9

Cited by 1 publication

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“…A common measure of homogeneity is the CoV of the concentration profile at a crosssection, as defined in equation ( 4) (Hirschberg et al 2009). Examples of applications can be found in Pust et al (2006) and Hsieh and Huang (2008):…”

Section: Quantitative Evaluation Of the Degree Of Mixingmentioning

confidence: 99%

Liquid mixing enhanced by pulse width modulation in a Y-shaped jet configuration

Xia¹,

Zhong²

2013

Fluid Dyn. Res.

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In this paper, mixing between two fluid streams, which are injected into a planar mixing channel via a Y-shaped confluence section at the same volume flow rate, is studied experimentally. The injection of the two fluid streams is controlled by two separate solenoid valves, which are operated with a phase difference of 180 • , using pulse width modulation. The experiments are conducted using water at a mean Reynolds number between 83 and 250, a range of pulsation frequencies and two duty cycles (25 and 50%). Both particle-image velocimetry and planar laser-induced fluorescence technique are used to visualize the flow patterns and to quantify the mixing degree in the mixing channel. This experiment shows that the pulsation of each jet produces vortical structures, which promotes mixing via vortex entrainment and vortex breakup, and at the same time the mixing is also greatly enhanced by sequential segmentation produced by a 180 • out-of-phase pulsation of the two jets. This mixing enhancement method is effective at a Reynolds number greater than 125 with a mixing degree of 0.9 being achieved. For the Reynolds numbers studied in the present experiments, an optimal frequency exists, which corresponds to a Strouhal number in the range of 0.5-2. Furthermore, at a given mean Reynolds number a lower duty cycle is found to produce a better mixing due to the resultant higher instantaneous Reynolds number in the jet flow. It is also found that pulsation of only one jet can produce a similar mixing effect.

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Section: Quantitative Evaluation Of the Degree Of Mixingmentioning

confidence: 99%