Conex 2004

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CONEX MEETING IN WARSAW Midterm report
Experimental investigation and numerical
modelling of the flow through the emulsifier
S. Blonski T.A. Kowalewski
Polish Academy of Sciences Institute of
Fundamental Technological Research
http//fluid.ippt.gov.pl/conex
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MAIN TASKS

1. Emulsification by liquid jet break-up drop size
   distribution and velocities.
2. Drop-drop interaction in liquid jets PIV
   method.
3. Drop-drop interaction in turbulent flow direct
   observation of drop break-up and coalescence by a
   high-speed camera.
4. Drop-particle interaction PIV method.
5. Optical observations of the composite layer
   formation by high-speed camera.

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OUR TASKS FOR MID-TERM REPORT

• Simulation of micro-emulsion by molecular
  dynamics
• Properties of emulsions in time dependent
  flow fields
• Production of droplets emulsion in turbulent
  flow

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OUR TASKS FOR MID-TERM REPORT
Emulsifier proposed by Sophia
Emulsion of of silicone oil in water
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EXPERIMENTAL TASK
Experimental cell with optical access for flow
investigation inside emulsifier
High speed imaging and velocity measurements for
FLAT - 2D SIMPLIFICATION gap 0.5mm x 15mm,
flow rate 60.10-6 m3/s.
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EXPECTED RESULTS

• Instantaneous velocity and vorticity
• Flow structure
• Turbulence transport coefficients
• Stress field
• Mixing properties

• Validation of the CFD models
• Optimisation of the drops size and shape
• Optimisation of the emulsifier geometry

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LABORATORY EQUIPMENT

• Full Field Measurements

• Epifluorescent microscope Nikon ECLIPSE E-50i
• PIV Camera PCO SensiCam (resolution 1280x1024)
• High Speed CMOS Camera PCO 1200.hs (up to
  636fps in full resolution 1280x1024)
• Double Pulse Laser Nd-YAG - SoloPIV NewWave
  (30mJ per pulse)
• Laser CW Ar 3W

• Other equipment

• Optical system for forming and redirection of
  laser light (lenses, mirrors, etc.)
• Pressure system (gas cylinder with argon,
  pressure regulator and conduits, pressure sensor)

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EXPERIMENTAL SETUP
Schematic setup for microPIV
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EXPERIMENTAL SETUP
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OUR QUESTIONS TO ANSWER
Production of droplets emulsion in turbulent
flow

• Does droplet size correlate with a simple
  shear-flow based Taylor theory?

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THEORETICAL ESTIMATION OF DROPS SIZE

• Droplet radius a , where
• ? medium viscosity
• ?d drops viscosity
• ? interfacial tension
• G velocity gradient

Assuming ? 10-3 N/m, ? 10-3 Ns/m2, ?d
0.48 Ns/m2, G 8.85104 s-1 (from numerical
simulation) we arrive to droplet radius a
4.510-6m
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EXPERIMENTAL RESULTS
Drops observed under microscope just after
processing element
Average size of droplets 0.17mm, smallest visible
droplets 10-5m
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OUR QUESTIONS TO ANSWER
Production of droplets emulsion in turbulent
flow

• Is flow turbulent, what is the critical Re number?

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EXPERIMENTAL INVESTIGATION
zone 1 2.5 x 15 mm zone 2 0.5 x 15 mm zone
3 7.5 x 15 mm
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REYNOLDS NUMBER IN SELECTED ZONES
Reynolds Number based on hydraulic diameter
Reynolds Number

• where
• ? density (for water)
• l hydraulic diameter
• ? velocity
• ? viscosity (for water)

Hydraulic diameter is defined
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REYNOLDS NUMBER IN SELECTED ZONES
Reynolds Number based on altitude of the channel
Reynolds Number

• where
• ? density (for water)
• l altitude of the channel
• ? velocity
• ? viscosity (for water)

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EXPERIMENTAL RESULTS
Visualization of the flow inside emulsifier
2 mm
Recording speed 1000 fps Exposure time 100 ?s
(v1.1m/s, Re2900) Display speed 5 fps (200 x
slow-down)
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EXPERIMENTAL RESULTS
Laminar turbulent transition
flow direction
processing element
Laminar flow v 0.1 m/s Re 250
Transition flow v 0.4 m/s Re 1000
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EXPERIMENTAL RESULTS
Preliminary micro-PIV results
4 mm
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NUMERICAL SIMULATION
CFD Modelling Using Fluent 6.1
Numerical simulation was done in following
steps I 2D steady flow, turbulence model
k-? II 2D unsteady flow, turbulence model
k-? III 3D unsteady laminar flow IV 3D steady
flow, turbulence model k-? V 3D unsteady flow,
turbulence model k-?
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NUMERICAL SIMULATION
Conditions for 3D simulation
Geometry for numerical simulation
Generated mesh
Mesh structural, 1302111 cells, 4025630 faces,
1422300 nodes Medium water Inlets
velocity-inlet, v0.8 m/s Outlet pressure outlet
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NUMERICAL SIMULATION
Laminar simulation
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NUMERICAL SIMULATION
Model k-?, steady flow
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NUMERICAL SIMULATION
3D Model k-?, steady flow
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NUMERICAL SIMULATION
Model k-?, unsteady flow
Time step 10-5 s Real duration of animation
0.055 sec (550 time steps)
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NUMERICAL SIMULATION
Model k-?, unsteady flow,3D
Turbulent Kinetic Energy
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CONSLUSIONS

• Soft turbulence, possible we are very closed
  to transition
• point
• Simple, shear flow based Taylor model may work
  for
• drop size at low flow rates
• Flow instability generated already be
  cylindrical
• obstacles at the inlet is it enough to be
  called turbulence?
• Validation of the numerical models possible
  after PIV
• measurements are ready