Recirculation in swirling flow - A manifestation of vortex breakdown

Escudier, M. P.; Keller, Jakob J.

doi:10.2514/3.8878

Cited by 206 publications

(107 citation statements)

References 12 publications

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“…III. It turned out that vortex breakdown was observed for swirl numbers S 1:1 (vortex breakdown was defined as an isolated axisymmetric recirculation zone which appears in the region downstream of a nozzle exit [31]). A comparison of this finding with experience obtained regarding the onset of vortex breakdown in other flows was very complicated.…”

Section: Swirl Effectsmentioning

confidence: 99%

Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

et al. 2009

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This paper reports the results of numerical investigations of swirling turbulent jet flows by large-eddy simulation. Reynolds-averaged Navier-Stokes simulations are used to generate mean inflow data. Fluctuations are added to the profiles of the means to produce instantaneous inflow data. The instantaneous inflow data are correlated such that the characteristic length and time scales of inflowing turbulent eddies are consistent with the corresponding Reynoldsaveraged Navier-Stokes profiles imposed at the inlet. The resulting large-eddy simulation method is validated against experimental data of both swirling and nonswirling turbulent jets. The application of the validated largeeddy simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart the typical ring structures of nonswirling turbulent jets into two modes: a helical mode and streamwise braid structures. The interaction of these two modes generates unorganized turbulence that enhances the turbulent mixing. An analysis of the mixing enhancement by swirl shows a significant increase of the turbulent mixing efficiency of scalars with the swirl number (of up to 21.7% for the cases considered).

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Section: Swirl Effectsmentioning

confidence: 99%

Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

et al. 2009

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“…The liquid flow is swirled by swirler (1), then, passing through a nozzle, it is fed to the zone of sudden expansion. Then, in this zone, it interacts with the flow, swirled by second swirler (3). Depending on the method of liquid supply to the second swirler, co-swirling (white arrows) and counter-swirling (dark arrows) of two flows are achieved between the swirlers of the first and second stages of the working section.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, one of the most interesting problems in the field of swirling flows is investigation of characteristics of behavior of the interacting swirling flows [2][3]. The need for such research is firstly caused by the use of the counter-swirling flows in energy dissipation devices and vortex combustion chambers.…”

Section: Introductionmentioning

confidence: 99%

Isothermal modeling of aerodynamic structure of the swirling flow in a two-stage burner

2017

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Abstract. The work deals with the experimental study of the aerodynamic structure of a swirling flow in the isothermal model of two-stage vortex combustion chamber. The main attention is focused on the process of flow mixing of two successively connected tangential swirlers of the first and second stages of the working section. Data on flow visualization are presented for two patterns of flow swirling. Time-averaged profiles of the axial and tangential velocity components are obtained with the help of laser-Doppler anemometer. In the case of flow co-swirling between two stages of the working section, instability of a secondary flow in the form of precessing vortex was distinguished. For the regime with counter flow swirling, effective mixing of the swirl flows was found; this was reflected by formation of the flow with uniform distribution of axial velocity over the cross-section.

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“…the effects of downstream boundary conditions in subcritical flow; see Escudier & Keller 1985). Mattner et al (2002) also showed that the annular reverse axial flow regime was the result of a complicated transition process as the swirl intensity was increased following vortex breakdown, which first occurred at β > 23…”

Section: Introductionmentioning

confidence: 99%

Vortical flow. Part 2. Flow past a sphere in a constant-diameter pipe

2003

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This paper describes an experimental and numerical investigation of concentrated vortex flow past a sphere in a constant-diameter pipe. As the swirl was increased at a fixed sphere Reynolds number of approximately 1100, the length of the mean downstream separation bubble decreased. For a small range of swirl intensity, an almost stagnant separation bubble formed on the upstream hemisphere. A further increase in swirl caused the bubble to become unstable and develop into an unsteady spiral disturbance. At very high swirl the downstream separation bubble was eliminated and an unsteady separation zone extended far upstream. Calculations of the vorticity field from surface fits to azimuthal and axial velocity data suggest that upstream separation is caused by the distortion of vortex filaments in the diverging flow approaching the sphere. Numerical solutions of steady inviscid axisymmetric flow past a sphere exhibit a fold in the vicinity of upstream separation. It is suggested that this accounts for the extreme sensitivity encountered in the experiments.

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Recirculation in swirling flow - A manifestation of vortex breakdown

Cited by 206 publications

References 12 publications

Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

Large-Eddy Simulation of Swirling Turbulent Jet Flows in Absence of Vortex Breakdown

Isothermal modeling of aerodynamic structure of the swirling flow in a two-stage burner

Vortical flow. Part 2. Flow past a sphere in a constant-diameter pipe

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