Turbulent mixing in the confined swirling flow of a multi‐inlet vortex reactor

Liu, Zhenping; Hitimana, Emmanuel; Olsen, Michael G.; Hill, James C.; Fox, Rodney O.

doi:10.1002/aic.15572

Cited by 20 publications

(22 citation statements)

References 29 publications

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“…The values are obtained at 10 mm axial plane from the bottom plate of the unit. For low solid loadings (up to 1.5 g), the gas velocity behavior is corresponding to free‐swirl motion and increases toward the central exhaust ( r = 10 mm). The flow is as such where the gas flow affects the solids flow but not vice versa.…”

Section: Resultsmentioning

confidence: 99%

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

et al. 2019

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Vortex units are commonly considered for various single and multiphase applications due to their process intensification capabilities. The transition from gas-only flow to gas-solid flow remains largely unexplored nonetheless. During this transition, primary flow phenomenon, jets, and secondary flow phenomena, counterflow and backflow, are substantially reduced, before a rotating solids bed is established.This transitional flow regime is referred to as the vortex suppression regime. In the present work, this flow transition is identified and validated through experimental and computational studies in two vortex units with a scale differing by a factor of 2, using spherical aluminum and alumina particles. This experimental data supports the proposed theoretical particle monolayer solids loading that allows estimation of vortex suppression regime solids capacity for any vortex unit. It is shown that the vortex suppression regime is established at a solids loading theoretically corresponding to a monolayer being formed in the unit for 1g-Geldart D-and 1g-Geldart B-type particles. The model closely agrees with experimental vortex suppression range for both aluminum and alumina particles. The model, as well as the experimental data, shows that the flow suppression regime depends on unit dimensions, particle diameter, and particle density but is independent of gas flow rate.This combined study, based on experimental and computational data and on a theoretical model, reveals the vortex suppression to be one of the basic operational parameters to study flow in a vortex unit and that a simple monolayer model allows to estimate the needed solids loading for any vortex device to induce this flow transition. K E Y W O R D Sgas-solid vortex reactor, gas-solid vortex units, monolayer model, process intensification, vortex suppression regime Abbreviations: GSVR, gas-solid vortex reactor; GSVU, gas-solid vortex unit; GVU, gasvortex unit; HDPE, high density polyethylene.

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Section: Resultsmentioning

confidence: 99%

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

et al. 2019

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“…Confined vortex flow finds significance in numerous industrial processes. Such flows are used for mixing (Levy and Albagli, 1991;Liu et al, 2017) as well as for the separation of two or more phases with different densities (Sommerfeld and Qiu, 1993), and also for flow stabilisation (as in swirl burners (Froud et al, 1995)). One popular application of swirldominated flow and the subject of this study is the cyclone separator.…”

Section: Introductionmentioning

confidence: 99%

Revealing the details of vortex core precession in cyclones by means of large-eddy simulation

Brar

Derksen

2020

Chemical Engineering Research and Design

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We investigate the three-dimensional, time-dependent behaviour of coherent flow structures inside two cyclone separator geometries, a Stairmand cyclone and a swirl tube, operating in the turbulent regime. For this, large-eddy simulations (LES) with a standard Smagorinsky subgrid-scale model are carried out on the single-phase flow employing a nonorthogonal curvilinear hexahedral mesh. Reynolds numbers (Re) are in the range 910 4 to 410 5 .The simulations successfully capture the quasi-periodic precessing vortex core (PVC) phenomenon. The spectra derived from the temporal signals of different flow variables viz. static pressure, tangential velocity, axial velocity and radial velocity in the Stairmand cyclone exhibit two distinct frequencies at all Re, whereas the spectra for the swirl tube show a single peak. These spectra strongly resemble those reported in the experimental literature. The periodicity pertaining to the inner vortex about its rotational axis is also analysed. Next, the effect of Re on the two distinct spectral peaks have been evaluated for the Stairmand cyclone.Lastly, we present the effect of Re on mean and fluctuating fields and their variations along the geometrical axis of the cyclone.

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“…Musa et al 17 studied the ignition and flame stability of high‐density polyethylene solid fuel with incoming swirling air through a solid fuel ramjet and found that inducing swirling flow could improve the combustion efficiency and stability. Liu et al 18 studied the mixing performance in the turbulent swirling flow of a multiinlet vortex reactor by using planar laser‐induced fluorescence (PLIF) and the mixing mechanisms in the reactor were discussed. It is noted that reports on the swirling flow in the literature mainly focus on gas mixing and few works can be found for the liquid mixing, which is more widely used in chemical production.…”

Section: Introductionmentioning

confidence: 99%

Liquid mixing intensification by adding swirling flow in the transverse jet mixer

Zhang

et al. 2021

AIChE Journal

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In this study, effect of swirling addition on the liquid mixing behavior of multiorifice‐impinging transverse jet mixer has been investigated by planar laser‐induced fluorescence as well as large eddy simulation (LES). In the case of swirling addition into the jet flow, there exists an optimized swirling jet angle or optimized jet‐to‐cross velocity ratio for the fixed mixer configuration. A larger swirling jet angle will make the flow dominated by the swirling, resulting in a slower mixing process. Interaction of swirling crossflow with no‐swirling‐injected streams, or with swirling‐injected streams in the opposite direction is beneficial for the mixing. LES predictions show that many small vortices are produced homogenously due to intensified impingement in the case of opposite swirling directions, leading to a relative fast mixing process in few milliseconds. Whereas the mixing is restrained when the swirling directions of two flows are the same.

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Turbulent mixing in the confined swirling flow of a multi‐inlet vortex reactor

Cited by 20 publications

References 29 publications

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

Revealing the details of vortex core precession in cyclones by means of large-eddy simulation

Liquid mixing intensification by adding swirling flow in the transverse jet mixer

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