Visualization the different type of vortex breakdown in conical pipe flow with high cone angle

Abstract The current work studies a swirling laminar viscous pipe flow with a controllable swirl number and varying pipe divergence cone angle. Such flows are widely used in various engineering applications. When a certain level of flow swirl is reached, a phenomenon called vortex breakdown occurs, the characteristics of which depend on the intensity of swirling of the flow and the Reynolds number. However, in addition to these two parameters, an important influence is exerted by the pipe opening angle, which often does not allow generalizing the results obtained in the pipe flow with even slightly different angles. Since experimentally it is quite difficult and expensive to change the pipe angle, especially considering the water as working fluid, this issue could be solved using CFD techniques. Using the design study, 63 different combinations of S and α are considered. The effect of the pipe divergence angle on the position of the bubble vortex breakdown and its properties is demonstrated. It is shown that there is a nonlinear relationship between the position of the bubble breakdown onset and the minimum value of the axial velocity at the axis depending on the opening angle of the cone.

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Structures of Confined Vortex Breakdown in Constant Diameter Pipe Flow

Journal of Hydrodynamics ◽

10.1016/s1001-6058(08)60154-7 ◽

2009 ◽

Vol 21 (3) ◽

pp. 341-346 ◽

Cited By ~ 3

Author(s):

Ze Wang ◽

Shan-qun Chen

Keyword(s):

Pipe Flow ◽

Vortex Breakdown ◽

Constant Diameter ◽

Diameter Pipe

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Velocity Profile Measurements of a Swirling Pipe Flow Associated with Vortex Breakdown

The Journal of the Japan Society of Aeronautical Engineering ◽

10.2322/jjsass1969.28.200 ◽

1980 ◽

Vol 28 (315) ◽

pp. 200-205

Author(s):

Toshihiko IKEDA ◽

Mitsuo SAKATA ◽

Tyozi HORIKOSI

Keyword(s):

Velocity Profile ◽

Pipe Flow ◽

Vortex Breakdown

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Nonlinear spiral waves in rotating pipe flow

Journal of Fluid Mechanics ◽

10.1017/s0022112088001193 ◽

1988 ◽

Vol 190 ◽

pp. 39-54 ◽

Cited By ~ 21

Author(s):

N. Toplosky ◽

T. R. Akylas

Keyword(s):

Pipe Flow ◽

Vortex Breakdown ◽

Reynolds Numbers ◽

Finite Amplitude ◽

Spiral Waves ◽

Slow Rotation ◽

Mean Flow ◽

Weakly Nonlinear ◽

Mean Pressure ◽

Rotating Pipe Flow

A numerical investigation of finite-amplitude, non-axisymmetric disturbances, in the form of travelling spiral waves, is made in pipe flow with superimposed solid-body rotation. Rotating pipe flow is found to be supercritically unstable both in the rapid and slow-rotation regimes. Earlier weakly nonlinear calculations, suggesting subcritical instability in the slow-rotation limit, are shown to be in error. Bifurcating neutral waves are calculated for various axial and azimuthal Reynolds numbers and wavenumbers. For fixed axial mean pressure gradient, the axial mean flow induced by these waves gives rise to a significant flux defect, in certain cases as large as 40-50% of the undisturbed mass flux; the possible relevance of this finding to the phenomenon of vortex breakdown is pointed out. In non-rotating pipe flow, no neutral disturbances in the assumed form of spiral waves are found for moderate Reynolds numbers; this indicates that previous conjectures, regarding a possible connection between nonlinear spiral waves in slowly rotating pipe flow and the asymptotic neutral states of Smith & Bodonyi (1982) in non-rotating pipe flow, are not valid.

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