Vortex stability and breakdown - Survey and extension

Leibovich, S.

doi:10.2514/3.8761

Cited by 492 publications

(189 citation statements)

References 46 publications

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“…An inviscid base flow is obtained initially, followed by a boundary layer type correction at the centerline. In modeling confined vortices, it is common to assume that the flow is both axisymmetric and that the swirl velocity is axially invariant (see Leibovich, 1984). The equations for the inviscid flow, after applying these assumptions, reduce to:…”

Section: Laminar Core Modelmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of the Bidirectional Vortex Using Particle Image Velocimetry

Maicke¹,

Majdalani²

2012

The Particle Image Velocimetry - Characteristics, Limits and Possible Applications

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Section: Laminar Core Modelmentioning

confidence: 99%

“…Bloor & Ingham (1987) note that the unbounded behavior at the centerline appears to be a common characteristic of inviscid models to the extent of becoming archetypical (cf. Leibovich, 1984). To treat this core singularity, the second-order viscous terms in the θ-momentum equation must be considered.…”

Section: Laminar Core Modelmentioning

confidence: 99%

Characterization of the Bidirectional Vortex Using Particle Image Velocimetry

Maicke¹,

Majdalani²

2012

The Particle Image Velocimetry - Characteristics, Limits and Possible Applications

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“…The dynamics of the swirling flow in a pipe at high levels of rotation is dominated by flow instabilities and the vortex breakdown phenomena (see Sarpkaya, 1,2 Faler and Leibovich, 3 Leibovich,4 Brucker and Althaus, 5 Mattner et al, 6 Liang and Maxworthy, 7 and Dennis et al 8 ). In stationary pipes, the instabilities range from helical waves to the two major types of breakdown, the axisymmetric bubble and the spiral breakdown.…”

Section: Introductionmentioning

confidence: 99%

Instability modes on a solid-body-rotation flow in a finite-length pipe

et al. 2017

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Analysis of the flow property of aluminum alloy AA6016 based on the fracture morphology using the hydroforming technology AIP Advances 7, 095111 (2017); https://doi.org/10.1063/1.4998539Microrheology of magnetorheological silicone elastomers during curing process under the presence of magnetic field AIP Advances 7, 095004 (2017); https://doi.org/10.1063/1.5002121Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study AIP Advances 7, 095007 (2017); https://doi.org/10.1063/1.5002528 AIP ADVANCES 7, 095112 (2017) Instability modes on a solid-body-rotation flow in a finite-length pipe Numerical solutions of the incompressible Navier-Stokes equations are obtained to study the time evolution of both axisymmetric and three-dimensional perturbations to a base solid-body-rotation flow in a finite-length pipe with non-periodic boundary conditions imposed at the pipe inlet and outlet. It is found that for a given Reynolds number there exists a critical swirl number beyond which the initial perturbations grow, in contrast to the solid-body rotation flow in an infinitely-long pipe or a finitelength pipe with periodic inlet and exit boundary conditions for which the classical Kelvin analysis and Rayleigh stability criterion affirm neutrally stable for all levels of swirl. This paper uncovers for the first time the detailed evolution of the perturbations in both the axisymmetric and three-dimensional situations. The computations reveal a linear growth stage of the perturbations with a constant growth rate after a brief initial period of decay of the imposed initial perturbations. The fastest growing axisymmetric and three-dimensional instability modes and the associated growth rates are identified numerically for the first time. The computations show that the critical swirl number increases and the growth rate of instability decreases at the same swirl number with decreasing Reynolds number. The growth rate of the axisymmetric mode at high Reynolds number agrees well with previous stability theory for inviscid flow. More importantly, three-dimensional simulations uncover that the most unstable mode is the spiral type m = 1 mode, which appears at a lower critical swirl number than that for the onset of the axisymmetric mode. This spiral mode grows faster than the unstable axisymmetric mode at the same swirl. Moreover, the computations reveal that after the linear growing stage of the perturbation the flow continues to evolve nonlinearly to a saturated axisymmetric vortex breakdown state. © 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).[http://dx.doi.org/10.1063/1.4993643]

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“…Type and position of vortex breakdown is a function of Reynold number and swirl number [10,11]. As research continues, other forms modes of disruption of the vortex core were observed in some later studies [12,13]. Leibovich et al [12] and Faler et al [13] observed seven distinct disruption modes of the vortex core which were bubble type, axisymmetric with asymmetric tail, spiral, flattened bubble, flattened bubble spiral, double helix and sheared filament type as Reynold number and swirl number are varied.…”

Section: Introductionmentioning

confidence: 99%

LES of Swirl Angle on Combustion Dynamic and NOx Formation in a Hybrid Industrial Combustor

Shi¹,

Fu²,

Shen³

et al. 2016

IJHT

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Impact of diagonal swirler vane angle on combustion dynamic and NOx formation characteristic in a hybrid industrial combustor is numerically studied using a full compressible large eddy simulation approach. The predicted results show that increase the swirler vane angle enlarges the magnitude of the CTRZ and thus the coherent structure and off-axis motions of vortex cores which increase the pressure oscillations amplitude. Phenomenon of combustion instability does not occur due to the introduction of pilot diffusion flame. Formation rate of NOx is relatively slower in pilot diffusion flame, because excess air contained in pilot fuel streams dilutes the flame temperature. Regions with peak flame temperature and maximum formation rate of NOx located in vicinity to the sidewall of combustion chamber especially in the shell side. Proper increase of diagonal swirler vane angle to enlarges the divergence angle of flame and reduces the recirculation of hot gases and combustion products in outer recirculation zones to control peak temperature of flame is an effective means to control NOx emissions for this hybrid industrial combustor. Further increase the diagonal swirler vane angle will have relatively smaller impacts on compressing the NOx emission due to the confinement of combustion chamber.

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Vortex stability and breakdown - Survey and extension

Cited by 492 publications

References 46 publications

Characterization of the Bidirectional Vortex Using Particle Image Velocimetry

Characterization of the Bidirectional Vortex Using Particle Image Velocimetry

Instability modes on a solid-body-rotation flow in a finite-length pipe

LES of Swirl Angle on Combustion Dynamic and NOx Formation in a Hybrid Industrial Combustor

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