Swirling Flow of a Viscoelastic Fluid With Free Surface—Part I: Experimental Analysis of Vortex Motion by PIV

2005 ◽  
Vol 128 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Jinjia Wei ◽  
Fengchen Li ◽  
Bo Yu ◽  
Yasuo Kawaguchi
Keyword(s):  
Free Surface ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Vortex Motion ◽  
Surfactant Solution ◽  
Particle Image Velocimetry System ◽  
Meridional Plane ◽  
Cylindrical Wall ◽  
Rotating Disc ◽  
Solution Flow

The swirling flows of water and CTAC (cetyltrimethyl ammonium chloride) surfactant solutions (50-1000ppm) in an open cylindrical container with a rotating disc at the bottom were experimentally investigated by use of a double-pulsed PIV (particle image velocimetry) system. The flow pattern in the meridional plane for water at the present high Reynolds number of 4.3×104 differed greatly from that at low Reynolds numbers, and an inertia-driven vortex was pushed to the corner between the free surface and the cylindrical wall by a counter-rotating vortex caused by vortex breakdown. For the 1000ppm surfactant solution flow, the inertia-driven vortex located at the corner between the bottom and the cylindrical wall whereas an elasticity-driven reverse vortex governed the majority of the flow field. The rotation of the fluid caused a deformation of the free surface with a dip at the center. The dip was largest for the water case and decreased with increasing surfactant concentration. The value of the dip was related to determining the solution viscoelasticity for the onset of drag reduction.

Swirling Flow of a Viscoelastic Fluid With Free Surface: Part I — Experimental Analysis of Vortex Motion by PIV

2004 ◽  
Author(s):  
Jinjia Wei ◽  
Fengchen Li ◽  
Bo Yu ◽  
Yasuo Kawaguchi
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Particle Image Velocimetry System ◽  
Meridional Plane ◽  
Cylindrical Wall ◽  
Rotating Disc ◽  
Solution Flow ◽  
Surfactant Solutions

The swirling flows of water and CTAC (cetyltrimethyl ammonium chloride) surfactant solutions in an open cylindrical container with a rotating disc at the bottom were experimentally investigated by use of a double-pulsed PIV (particle image velocimetry) system. The mass concentrations of CTAC solutions were in the range of 50–1000 ppm, and the Reynolds number based on angular velocity, kinematic viscosity of water and radius of rotating disc was fixed at 4.3 × 104. The aspect ratio of the height of the liquid filled into the cylindrical vessel to the radius of the vessel was set to 1.0. The secondary flow patterns in the meridional plane and the tangential velocities were obtained. The flow pattern in the meridional plane for water at the present high Reynolds number differed greatly from that at low Reynolds numbers, and an inertia-driven vortex was pushed to the corner between the free surface and the cylindrical wall by a counter-rotating vortex caused by vortex breakdown. For the 1000-ppm surfactant solution flow, the inertia-driven vortex located at the corner between the bottom and the cylindrical wall whereas an elasticity-driven reverse vortex governed the majority of the flow field. The radial distributions of the time-averaged tangential velocities also differed for water and surfactant solutions. The rotation of the fluid caused a deformation of the free surface with a dip at the center. The dip was largest for the water case and decreased with increasing surfactant concentration.

Experimental Study of Swirling Flow of a Viscoelastic Fluid With Deformed Free Surface

2006 ◽  
Author(s):  
Feng-Chen Li ◽  
Masamichi Oishi ◽  
Yasuo Kawaguchi ◽  
Nobuyuki Oshima ◽  
Marie Oshima
Keyword(s):  
Free Surface ◽  
Water Flow ◽  
Viscoelastic Fluid ◽  
Swirling Flow ◽  
Solution Concentration ◽  
Force Balance ◽  
Meridional Plane ◽  
Solution Flow ◽  
Secondary Velocity ◽  
Cetyltrimethyl Ammonium

An experimental investigation was performed on the swirling flow of viscoelastic fluid with deformed free surface in a cylindrical container driven by the constantly rotating bottom wall. The tested fluid was an aqueous solution of CTAC (cetyltrimethyl ammonium chloride), which is a cationic surfactant. Water, 40ppm, 60ppm and 200ppm CTAC solution flows were tested at Froude numbers ranging from 2.59 to 16.3. PIV was used to measure the secondary velocity field in the meridional plane and the deformed free-surface level was extracted from the PIV images. At a similar Froude number, the depth of the dip formed at the center region of the free surface was decreased for CTAC solution flow compared with water flow. The inertia-driven vortex at the up-right corner in the meridional plane becomes more and more weakened with increase of the solution concentration or viscoelasticity. Through analyzing the overall force balance compared with water flow, the first normal stress difference or the weak viscoelasticity was estimated for the dilute CTAC solution flows.

Swirling Flow of a Viscoelastic Fluid With Free Surface: Part II — Numerical Analysis With Extended Marker-and-Cell Method

2004 ◽  
Author(s):  
Bo Yu ◽  
Jinjia Wei ◽  
Yasuo Kawaguchi
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Turbulence Model ◽  
Swirling Flow ◽  
Surfactant Solution ◽  
Secondary Flows ◽  
Surface Shape ◽  
Alternative Methods ◽  
Large Reynolds Number ◽  
Meridional Plane

In Part I [1], we presented the experimental results for swirling flows of water and cetyltrimethyl ammonium chloride (CTAC) surfactant solution in a cylindrical vessel with a rotating disk located at the bottom for a Reynolds number of around 4.3 × 104 based on the viscosity of solvent. For the large Reynolds number, violent irregular instantaneous secondary flows at the meridional plane were observed by use of a PIV system. Because of the limitations of our computer resources, we did not carry out DNS simulation for such a large Reynolds number. The LES and turbulence model are alternative methods, but a viscoelastic LES/turbulence model has not yet been developed for the surfactant solution. In this study, therefore, we limited our simulations to a laminar flow. The Marker-and-Cell (MAC) method proposed for Newtonian flow was extended to the viscoelastic flow to track the free surface, and the effects of Weissenberg number and Froude number on the flow pattern and surface shape were studied. Although the Reynolds number is much smaller than that of the experiment, the major experimental observations such as the inhibition of primary and secondary flows and the decrease of the dip of the free surface by the elasticity of the solution, were qualitatively reproduced in the numerical simulations.

Experiments on vortex breakdown in a confined flow generated by a rotating disc

1998 ◽  
Vol 370 ◽  
pp. 73-99 ◽  
Author(s):  
A. SPOHN ◽  
M. MORY ◽  
E. J. HOPFINGER
Keyword(s):  
Free Surface ◽  
Recirculation Zone ◽  
Vortex Breakdown ◽  
Rear Side ◽  
Asymmetric Flow ◽  
Steady State Flow ◽  
Rotating Disc ◽  
Pipe Flows ◽  
Confined Flow ◽  
Vortex Tubes

The steady-state flow generated by a rotating bottom in a closed cylindrical container and the resulting vortex breakdown bubbles have been studied experimentally. By comparing the flow inside two different container geometries, one with a rigid cover and the other with a free surface, we examined the way in which the formation and structure of the breakdown bubbles depend on the surrounding flow. Details of the flow were visualized by means of the electrolytic precipitation technique, whereas a particle tracking technique was used to characterize the whole flow field. We found that the breakdown bubbles inside the container flow are in many ways similar to those in vortex tubes. First, the bubbles are open with in- and outflow and second, their structure is, like in the case of vortex breakdown in pipe flows, highly axisymmetric on the upstream side of the bubble and asymmetric on their rear side. However, and surprisingly, we observed bubbles which are open and stationary at the same time. This shows that open breakdown bubbles are not necessarily the result of periodic oscillations of the recirculation zone. The asymmetry of the flow structure is found to be related to the existence of asymmetric flow separations on the container wall. If the angular velocity of the rotating bottom is increased the evolution of the breakdown bubbles is different in both configurations: in the rigid cover case the breakdown bubbles disappear but persist in the free surface case.

Experimental study on swirling flow of dilute surfactant solution with deformed free-surface

2008 ◽  
Vol 33 (1) ◽  
pp. 161-168 ◽  
Author(s):  
Feng-Chen Li ◽  
Yong Dong ◽  
Yasuo Kawaguchi ◽  
Marie Oshima
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Swirling Flow ◽  
Surfactant Solution

Vortex Motion in a Swirling Flow of Surfactant Solution With Drag Reduction in a Pipe

2003 ◽  
Author(s):  
Mizue Munekata ◽  
Kazuyoshi Matsuzaki ◽  
Hideki Ohba
Keyword(s):  
Drag Reduction ◽  
Turbulence Intensity ◽  
Pipe Flow ◽  
Vortex Core ◽  
Swirling Flow ◽  
Vortex Motion ◽  
Flow Characteristics ◽  
Surfactant Solution ◽  
Industrial Applications ◽  
Straight Pipe

A surfactant is well known as an additive that brings about drag-reduction in straight (non-swirling) pipe flow. However in industrial applications of the drag-reducing effect, many flow fields exist including the straight pipe flow. The purpose of this study is to investigate the flow characteristics of surfactant solution swirling pipe flow. The drag reducing effect is estimated from the measurement wall pressure loss and the velocity profiles on various pipe sections are measured by 2 dimensional LDV. Since the surfactant solution has viscoelasticity, interesting flow characteristics are shown. The decay of swirl, the vortex type and the turbulence intensity are discussed, compared with the water swirling flow. The oscillating of vortex core is also investigated.

Vortex Motion in a Swirling Flow of Surfactant Solution with Drag Reduction

2005 ◽  
Vol 128 (1) ◽  
pp. 101-106 ◽  
Author(s):  
Mizue Munekata ◽  
Kazuyoshi Matsuzaki ◽  
Hideki Ohba
Keyword(s):  
Drag Reduction ◽  
Pipe Flow ◽  
Swirling Flow ◽  
Vortex Motion ◽  
Flow Characteristics ◽  
Surfactant Solution ◽  
Industrial Applications ◽  
Laser Doppler Velocimeter ◽  
Straight Pipe ◽  
Forced Vortex

Surfactants are well known as additives which induce drag reduction in the straight (nonswirling) pipe flow. However, in industrial applications of the drag-reducing effect, many flow fields besides the straight pipe flow need to be considered. The purpose of this study is to investigate the flow characteristics of the surfactant solution in swirling pipe flow. The drag-reducing effect is estimated from the measurement of wall pressure drop and velocity profiles on various pipe sections by two-dimensional LDV (Laser Doppler Velocimeter). Since the surfactant solution has viscoelasticity, interesting flow characteristics are obtained. The decay of swirl, the vortex type and the turbulence intensity are discussed, compared with the swirling flow of the water. As the results, it is concluded that the change from Rankin’s combined vortex to the forced vortex at a more upstream section by suppressing progress of free vortex and stretch of forced vortex introduces considerable drag reduction. Oscillation of the vortex core is also investigated, and it is found that the oscillation is independent of swirl number.

scholarly journals Vortex breakdown of the swirling flow in a Lean Direct Injection burner

2020 ◽  
Vol 32 (12) ◽  
pp. 125118
Author(s):  
Yazhou Shen ◽  
Mohamad Ghulam ◽  
Kai Zhang ◽  
Ephraim Gutmark ◽  
Christophe Duwig
Keyword(s):  
Vortex Breakdown ◽  
Swirling Flow ◽  
Direct Injection ◽  
Lean Direct Injection ◽  
Injection Burner

Forced and Periodic Vortex Breakdown

1967 ◽  
Vol 89 (3) ◽  
pp. 609-615
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Experimental Study ◽  
Opposite Direction ◽  
Vortex Tube ◽  
Vortex Breakdown ◽  
Swirling Flow ◽  
Typical Data ◽  
Circular Orifice ◽  
Pros And Cons

The results of an experimental study of the forced and periodic breakdown of a confined vortex rotating in the opposite direction are presented. The vortex tube consists of two chambers connected by a short conduit through streamlined transitions. The upstream end is closed by a plain wall, and a circular orifice is provided at the downstream end. The swirling flow and the breaker-vortex are generated by introducing varying proportions of air or water through tangential ports located near the upstream and downstream walls of the unit. The cases of single breakdown and periodic breakdown are explored and typical data are presented for each case. Finally, the pros and cons of the two existing transition theories are discussed.

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