Flow Regimes in Two-Phase Hexane/Water Semibatch Vertical Taylor Vortex Flow

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Charlton Campbell ◽  
Michael G. Olsen ◽  
R. Dennis Vigil
Keyword(s):  
Vortex Flow ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Water Phase ◽  
Taylor Vortex ◽  
Two Phase ◽  
Annular Gap ◽  
Taylor Vortex Flow ◽  
Regime Map

Optical-based experiments were carried out using the immiscible pair of liquids hexane and water in a vertically oriented Taylor–Couette reactor operated in a semibatch mode. The dispersed droplet phase (hexane) was continually fed and removed from the reactor in a closed loop setup. The continuous water phase did not enter or exit the annular gap. Four distinct flow patterns were observed including (1) a pseudo-homogenous dispersion, (2) a weakly banded regime, (3) a horizontally banded dispersion, and (4) a helical flow regime. These flow patterns can be organized into a two-dimensional regime map using the azimuthal and axial Reynolds numbers as axes. In addition, the dispersed phase holdup was found to increase monotonically with both the azimuthal and axial Reynolds numbers. The experimental observations can be explained in the context of a competition between the buoyancy-driven axial flow of hexane droplets and the wall-driven vortex flow of the continuous water phase.

An Experimental Investigation of the Stability of Spiral Vortex Flow

1979 ◽  
Vol 21 (6) ◽  
pp. 397-402 ◽  
Author(s):  
M. M. Sorour ◽  
J. E. R. Coney
Keyword(s):  
Vortex Flow ◽  
Outer Cylinder ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Taylor Vortex ◽  
Vortex Cell ◽  
Annular Gap ◽  
Spiral Vortex ◽  
Axial Pressure Gradient ◽  
The Stability

The hydrodynamic stability of the flow in an annular gap, formed by a stationary outer cylinder and a rotatable inner cylinder, through which an axial flow of air can be imposed, is studied experimentally. Two annulus radius ratios of 0.8 and 0.955 are considered, representing wide- and narrow-gap conditions, respectively. It is shown that, when a large, axial pressure gradient is superimposed on the tangential flow induced by the rotation of the inner cylinder, the characteristics of the flow at criticality change significantly from those at zero and low axial flows, the axial length and width of the resultant spiral vortex departing greatly from the known dimensions of a Taylor vortex cell at zero axial flow. Also, the drift velocity of the spiral vortex is found to vary with the axial flow. Axial Reynolds numbers, Rea, of up to 700 are considered.

The Effect of Taylor Vortex Flow on the Radial Forces in an Annulus Having Variable Eccentricity and Axial Flow

1978 ◽  
Vol 100 (2) ◽  
pp. 210-214 ◽  
Author(s):  
J. E. R. Coney ◽  
J. Atkinson
Keyword(s):  
Vortex Flow ◽  
Outer Cylinder ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Radial Force ◽  
Taylor Vortex ◽  
Eccentric Annulus ◽  
Taylor Vortex Flow ◽  
Radial Forces ◽  
Force Variation

Results are presented in dimensionless form as obtained in an experimental study of the resultant radial force variation in an eccentric annulus formed by a stationary outer cylinder and a rotating inner cylinder, through which an axial flow of oil may be pumped. Two eccentricity ratios, 0.5 and 0.9, and three axial Reynolds numbers for the flow of the fluid in the annulus, 0, 25, and 50, are considered. It is shown that the onset of Taylor vortex flow has a marked effect on the magnitude and direction of the resultant radial force. The resultant forces and attitude angles are compared with those derived from Sommerfeld’s journal bearing theory. Comparisons are also made between critical Taylor numbers for the present investigation and those available in the literature.

The Effect of Taylor Vortex Flow on the Development Length in Concentric Annuli

1979 ◽  
Vol 21 (2) ◽  
pp. 59-64 ◽  
Author(s):  
D. A. Simmers ◽  
J. E. R. Coney
Keyword(s):  
Reynolds Number ◽  
Vortex Flow ◽  
Outer Cylinder ◽  
Outer Wall ◽  
Taylor Vortex ◽  
Rotational Flow ◽  
Development Length ◽  
Full Development ◽  
Annular Gap ◽  
Taylor Vortex Flow

Results are presented of an investigation into a developing, combined axial and rotational flow in an annular gap formed by a stationary outer cylinder and a rotatable inner cylinder for an annulus radius ratio of 0–8 and an axial Reynolds number of 1200. These results show that, in the Taylor vortex flow régime, the development length decreases with the parameter Re2a/Ta and that the greatest development length in an annular gap, for a given axial Reynolds number, occurs when the Taylor number is near to its critical value. Consideration of isothermal heat transfer through the outer wall of the annular gap suggests that, in the development of the flow, the Nusselt number rises to a high value before falling to a constant value, at full development.

Spectrum Analysis of the Taylor Vortex Flow With a Short Annulus Using the Ultra Sonic Velocity Profiler

2007 ◽  
Author(s):  
Hideki Kawai ◽  
Hiroshige Kikura ◽  
Hiroshi Takahashi
Keyword(s):  
Aspect Ratio ◽  
Vortex Flow ◽  
Linear Equations ◽  
Reynolds Numbers ◽  
Measuring System ◽  
Taylor Vortex ◽  
Concentrated Flow ◽  
Taylor Vortex Flow ◽  
Solid Liquid

Boundary effects with a short annulus of Taylor Vortex Flow (TVF) called Ekman boundary, are greatly related to the generation of the various bifurcation modes in vortex structure, which are obtained even in the same Reynolds numbers. Parameters such as the aspect ratio and the radius ratio (Γ and η) are important factors for determination of the flow modes, which have been studied by many researchers and now known as the multiple solutions of the non-linear equations. One of these modes is expected to have mild mixing effects in solid-liquid phase flow, which could be useful for developing new bioreactor equipment. In the present, the spatiotemporal velocity field in the modulated or chaotic flow of Taylor vortex with a small aspect ratio is visualized and measured precisely by using ultrasonic velocity profiler (UVP). Although the flow is dilute solid-liquid flow in the present, this measuring system can be extended to somewhat more concentrated flow regions.

An Experimental and Numerical Investigation of Flow Regimes in Narrow Gaps

2007 ◽  
Author(s):  
D. Deng ◽  
M. J. Braun
Keyword(s):  
Vortex Flow ◽  
Numerical Data ◽  
Flow Patterns ◽  
Experimental Results ◽  
Taylor Vortex ◽  
Particle Accumulation ◽  
Taylor Vortex Flow ◽  
The Difference ◽  
Narrow Gaps ◽  
Good Agreement

A comparison between the experimental and numerical results of the torque-speed graph is presented. There is a good agreement between the numerical and experimental data in the Couette, Taylor and Pre-wavy regimes. In the wavy regime, the numerical data are larger than the corresponding measured torques but the difference is confined to below 14%. The calculated critical speeds for the onset of Taylor vortex and Pre-wavy flows are slightly larger than the experimentally measured ones. Flow patterns in the longitudinal cross section view of the fluid between two cylinders are also presented. Experimental results show that Taylor vortex flow is replaced by a new equilibrium flow, which is defined as Pre-wavy flow. The major characteristic of the Pre-wavy flow is the appearance of zones of particle accumulation in the areas near the inner cylinder. These zones correspond to the low pressure regions. Except for the flow patterns in the Pre-wavy regime there is good agreement between the numerical simulation and the experimental results.

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