Ultrasonic Sensor for inline flow and rheology measurements of opaque, complex fluids R' L' Powell N - PowerPoint PPT Presentation

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Ultrasonic Sensor for inline flow and rheology measurements of opaque, complex fluids R' L' Powell N

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Ultrasonic Sensor for in-line flow and rheology measurements of. opaque, complex fluids ... In-line concentration measurement (Sucrose solutions) Yield stress ... – PowerPoint PPT presentation

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Title: Ultrasonic Sensor for inline flow and rheology measurements of opaque, complex fluids R' L' Powell N


1
Ultrasonic Sensor for in-line flow and rheology
measurements of opaque, complex fluids R. L.
Powell N. Dogan, M. J. McCarthy UC Davis
2
OUTLINE
  • Ultrasound Pulsed Doppler Velocimetry (UPDV)
  • Pointwise rheological measurements
  • Experimental set-up
  • Results
  • Flow profiles and rheograms (Starch suspensions
    and gels)
  • Comparison of UPDV with MRI (0.4 CMC)
  • In-line concentration measurement (Sucrose
    solutions)
  • Yield stress and flow profiles (Paper pulp)
  • Future Work

3
Ultrasound Pulsed Doppler Velocimetry
  • is the time of flight
  • x is the distance on measuring line
  • c is speed of sound
  • fo is basic frequency
  • fd is Doppler shift frequency

?
Transducer
r
Tube Wall
4
Ultrasound Pulsed Doppler Velocimetry
Sampling time (2d)/c
Doppler shift frequency spectra of this wave
will give the velocity spectra in this sample
volume
1stpulse
5
Pointwise Rheological measurements
Maximum shear rate
Zero shear rate
r
z
L
Velocity profile
Pressure difference
SHEAR RATE
SHEAR STRESS

6
Experimental set-up
Shear rate
Shear stress
UPDV electronics box
Ultrasound Transducer
Pressure drop measurements
7
Comparison of two imaging techniques
  • Limitations of UPDV in comparison to MRI
  • Attenuation of sound limits the penetration
    depth
  • High velocity gradient in the sample volume near
    the wall limits the resolution at the wall.

8
Off-line
Transducer
In-line
(Transmitter and Receiver)
q
Flow
V
(r)
z
Transducer
(Transmitter and Receiver)
Experimental set-up for off-line and in-line
sound speed and attenuation measurements at 2.25
MHz, 5MHz with sugar solutions
9
In-line concentration results
In-line data (T25C)
Off-line data
Kachanovskaya, et al., 1996 (T20C)
10
Flow profiles (Paper pulp A)
Length weighted fiber length 2.37 mm Fiber
width 21.4 ?, Fiber cell wall thickness 6.6
? Fiber width/cell wall thickness 3.24 Fiber
width/length9.03
11
Flow profiles (Paper pulp B)
Length weighted fiber length 1.15 mm Fiber
width 14.9 ?, Fiber cell wall thickness 4.2
? Fiber width/cell wall thickness 3.55 Fiber
width/length12.96
12
Fiber length distribution results
Paper pulp A
Paper pulp B
13
Yield stress comparison
Determination of yield stress using UPDV
14
Future Work
  • Pharmaceutical suspension (MCC)
  • Time dependent fluid (yogurt)
  • Polymer melts at room temperature, molecular
    weight distribution measurements (silicon)
  • Statistical error analysis approach to find the
    limits of the shear viscosity function
  • A simulation program
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