Vortex breakdown: Observations and explanations

Escudier, M. P.

doi:10.1016/0376-0421(88)90007-3

Cited by 444 publications

(198 citation statements)

References 50 publications

Supporting

Mentioning

189

Contrasting

Order By: Relevance

“…Note that the same vortex model (2.3), in the sense of Batchelor's vortex (Batchelor 1964) or the q-vortex, is commonly used to describe experimental swirl flows (Faler & Leibovich 1978;Escudier 1988;Alekseenko et al 1999) and in instability studies of swirling flows (see Heaton & Peake 2007 and references therein).…”

Section: Multiple Helical Modes Of Vortex Breakdownmentioning

confidence: 99%

Multiple helical modes of vortex breakdown

2011

View full text Add to dashboard Cite

Experimental observations of vortex breakdown in a rotating lid-driven cavity are presented. The results show that vortex breakdown for cavities with high aspect ratios is associated with the appearance of stable helical vortex multiplets. By using results from stability theory generalizing Kelvin's problem on vortex polygon stability, and systematically exploring the cavity flow, we succeeded in identifying two new stable vortex breakdown states consisting of triple and quadruple helical multiplets.

show abstract

Section: Multiple Helical Modes Of Vortex Breakdownmentioning

confidence: 99%

Multiple helical modes of vortex breakdown

2011

View full text Add to dashboard Cite

show abstract

“…This vortex model is commonly used in instability studies of swirling flows (see Heaton & Peake 2007, and references therein). To describe experimental swirl flows (Leibovich 1978;Escudier 1988;Alekseenko et al 1999), the Batchelor vortex model is usually referred to in the form…”

Section: Modelling Of the Longitudinal Vortexmentioning

confidence: 99%

Helical structure of longitudinal vortices embedded in turbulent wall-bounded flow

2009

View full text Add to dashboard Cite

Embedded vortices in turbulent wall-bounded flow over a flat plate, generated by a passive rectangular vane-type vortex generator with variable angle β to the incoming flow in a low-Reynolds-number flow (Re = 2600 based on the inlet grid mesh size L = 0.039 m and free stream velocity U ∞ = 1.0 m s −1 ), have been studied with respect to helical symmetry. The studies were carried out in a low-speed closed-circuit wind tunnel utilizing stereoscopic particle image velocimetry (SPIV). The vortices have been shown to possess helical symmetry, allowing the flow to be described in a simple fashion. Iso-contour maps of axial vorticity revealed a dominant primary vortex and a weaker secondary one for 20 • 6 β 6 40 • . For angles outside this range, the helical symmetry was impaired due to the emergence of additional flow effects. A model describing the flow has been utilized, showing strong concurrence with the measurements, even though the model is decoupled from external flow processes that could perturb the helical symmetry. The pitch, the vortex core size, the circulation and the advection velocity of the vortex all vary linearly with the device angle β. This is important for flow control, since one thereby can determine the axial velocity induced by the helical vortex as well as the swirl redistributing the axial velocity component for a given device angle β. This also simplifies theoretical studies, e.g. to understand and predict the stability of the vortex and to model the flow numerically.

show abstract

“…Combustion (with swirl for flame stabilization), turbo-machinery, and cyclone separators are a few examples. Experiments demonstrate that the swirl component has large-scale, and often counterintuitive effects on the flow field [1][2][3]. To mention a few phenomena: quasi-periodic oscillations (vortex core precession), subcritical flow (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, vortex breakdown was observed inside, or slightly upstream of the exit pipe. A third important observation when visualizing the flow was the clear distinction between the vortex core region where radial mixing is strongly suppressed, and the outer region that shows turbulent vortical structures (Taylor-Gö rtler vortices [2,13]). The large-eddy simulation of the vortex tube flow with a full representation of the geometry and operating conditions as used in the experiments is the subject of the study described in the present article.…”

Section: Introductionmentioning

confidence: 99%

Simulations of confined turbulent vortex flow

Derksen

2005

Computers & Fluids

View full text Add to dashboard Cite

Large-eddy simulations (LES) of the turbulent flow in a swirl tube with a tangential inlet have been performed. The geometry, and flow conditions were chosen according to an experimental study by [Escudier MP, Bornstein J, Zehnder N. Observations and LDA measurements of confined turbulent vortex flow. J Fluid Mech 1980;98:49-63]. Lattice-Boltzmann discretization was used to numerically solve the Navier-Stokes equations in the incompressible limit. Effects of spatial resolution and choices in subgridscale modeling were explicitly investigated with the experimental data set as the testing ground. Experimentally observed flow features, such as vortex breakdown and laminarization of the vortex core were well represented by the LES. The simulations confirmed the experimental observations that the average velocity profiles in the entire vortex tube are extremely sensitivity to the exit pipe diameter. For the narrowest exit pipe considered in the simulations, very high average velocity gradients are encountered. In this situation, the LES shows the most pronounced effects of spatial resolution and subgrid-scale modeling.

show abstract

Vortex breakdown: Observations and explanations

Cited by 444 publications

References 50 publications

Multiple helical modes of vortex breakdown

Multiple helical modes of vortex breakdown

Helical structure of longitudinal vortices embedded in turbulent wall-bounded flow

Simulations of confined turbulent vortex flow

Contact Info

Product

Resources

About