Experimental investigation of flow regimes of axisymmetric and planar opposed jets

Li, Weifeng; Yao, Tian-Liang; Liu, Haifeng; Wang, Fuchen

doi:10.1002/aic.12369

Cited by 47 publications

(39 citation statements)

References 37 publications

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“…It must be pointed out first that the self-sustained chaotic oscillation in RIM is related to the confined boundary condition, [15][16][17][18][19] which is different to the low-frequency periodic oscillation of axisymmetric opposed jets with excitations. Second, current results can be used to explain the low-frequency irregular oscillations reported in the experiments 20,21 but absent in the simulation and stability analysis. 13,14 This discrepancy is due to the different boundary conditions, because the velocity inlet in the simulation is laminar and constant, while the flow fluctuations and other disturbance more or less exist in experiments.…”

Section: Discussionmentioning

confidence: 95%

“…18,19 However, Stan and Johnson 20 have observed an irregular lowfrequency oscillation (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) for two opposed water jets, and the corresponding values of St are in the range of 2-8. In our previous study, 21 we have also observed some axial irregular oscillations or quasiperiodic oscillations for unrestricted axisymmetric opposed jets occasionally, whose peak frequency is about 10 Hz and St is in the range of 0.01-0.07. It should be pointed out that the irregular oscillation or quasiperiodic oscillation result form the exterior disturbances such as the flow fluctuation or smoke-wires.…”

Section: Introductionmentioning

confidence: 85%

“…It can be deduced that if the fluctuation of the excitation is random, the movement of the impingement plane will be irregular, which might be cause for the irregular oscillation in the literature. 20,21 It can be seen from Figures 8 and 9 that the impingement plane moves between two endpoints nearly with a uniform speed. So the mean movement velocity can be analyzed from the time series of locations of the impingement plane.…”

Section: Oscillation Frequencies Of Opposed Jets With Excitationsmentioning

confidence: 92%

“…It can be seen that the oscillation regimes of unrestricted axisymmetric opposed jets are basically different to the self-sustained oscillation in RIM and the periodic deflecting oscillation of planar opposed jets. [21][22][23] The excitation of modulated inflow has been widely used in the fluid mixing, 24,25 particle dispersion, 26 and liquid breakup. 27 However, the study of the flow regime of axisymmeric opposed jets with excitation is very rare, although it is important to fundamental fluid dynamics and applications.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study of oscillation of axisymmetric turbulent opposed jets with modulated airflow

Guo-Feng

et al. 2013

AIChE Journal

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Oscillation behaviors of axisymmetric opposed jets with modulated airflow were experimentally studied. The oscillation frequency, the oscillation amplitude, and the movement velocity of the impingement plane at various nozzle separations, excitation frequencies, and exit turbulence intensities have been investigated by a hot-wire anemometer and flow visualization technique combined with a high-speed camera. Results show that the oscillation frequency of the impingement plane is nearly equal to the excitation frequency, whereas the oscillation amplitude decreases with the increase of the excitation frequency. The full-scale amplitude oscillation occurs at low excitation frequencies and 2 L/D 8 (where L is the nozzle separation and D is the diameter of the nozzle exit). With the increase of the exit turbulence intensity caused by a turbulence generating plate, the oscillation amplitude decreases remarkably. Flow regimes of axisymmetric opposed jets with excitations are analyzed and discussed based on the experimental results.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 85%

Section: Oscillation Frequencies Of Opposed Jets With Excitationsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Experimental study of oscillation of axisymmetric turbulent opposed jets with modulated airflow

Guo-Feng

et al. 2013

AIChE Journal

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“…Much work has been done on the flow and turbulence characteristics of the flow field in coaxial impinging stream reactors [20][21][22][23][24]. Huai et al have studied drying and flow characteristics in a semicircular impinging stream reactor.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Studies on Flow and Turbulence Characteristics of Impinging Stream Reactors with Dynamic Inlet Velocity Variation

Liu

Yue²,

et al. 2018

Energies

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Impinging stream technique has been widely used in engineering industries. Insufficient data are available on the effects of dynamic inflow conditions on the flow and turbulence characteristics of an impinging stream reactor. In this study, we investigate and discuss the flow and turbulence characteristics of an impinging stream reactor with dynamic inlet velocity variation, e.g., sinusoidal, parabolic, step or triangular variation. The effects of period, amplitude, phase difference, mean inlet velocity and type of dynamic inlet velocity variation on the motional behaviors of the impinging surface and the mean turbulence kinetic energy (k) of the impingement region are investigated and discussed using particle image velocimetry (PIV) and computational fluid dynamics (CFD) at various values of L/D (the ratio of impinging spacing to nozzle diameter). The results show that the impinging surface makes back-and-forth motions in impinging stream reactors with dynamic inlet velocity variation. The mean k of the impingement region during one period is dominated by both the inlet velocity conditions and the geometric configuration. Dynamic inflow conditions bring more turbulence energy and pulsating characteristics to impinging zones over constant inlet velocity for an instantaneously moving impinging surface. Impinging stream reactors with dynamic inlet velocity variation provides more intense turbulence properties over conventional impinging stream reactors at the same mean inlet velocity. This work shows that the impinging streams with dynamic inlet velocity variation has strong potential for future relevant reactors and processes for engineering applications.

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Experimental study of flow regimes in three‐dimensional confined impinging jets reactor

et al. 2014

AIChE Journal

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Dynamic behaviors in a three‐dimensional confined impinging jets reactor (CIJR) were experimentally studied by a flow visualization technique at 100 ≤ Re ≤ 2000 and 2 ≤ D/d ≤ 12 (where D is the reactor diameter and d is the nozzle diameter). The effects of inlet Reynolds numbers (Re) and geometry configurations of the CIJR on the flow regimes have been investigated by a particle image velocimetry and a high‐speed camera. Results show that with the increasing Re, a segregated flow regime, a radial deflective oscillation, an axial oscillation and a vortex shedding regime emerge in turns in CIJR. A map of parameter space formed by the inlet Reynolds number (Re) and the normalized reactor diameter (D/d) has been presented. The effects of jet instability and confined boundary of the chamber on the flow regimes and their transition are also investigated and discussed. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3033–3045, 2014

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Experimental investigation of flow regimes of axisymmetric and planar opposed jets

Cited by 47 publications

References 37 publications

Experimental study of oscillation of axisymmetric turbulent opposed jets with modulated airflow

Experimental study of oscillation of axisymmetric turbulent opposed jets with modulated airflow

Experimental and Numerical Studies on Flow and Turbulence Characteristics of Impinging Stream Reactors with Dynamic Inlet Velocity Variation

Experimental study of flow regimes in three‐dimensional confined impinging jets reactor

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