Masato Hirota
MRI Measurements of Fibre
-
Suspension Flow in a Sudden
Contraction/Expansion
FP1005 & SIG43 Workshop
NTNU, Trondheim
24
-
26 October 2012
2
/17
Outline
1.
Introduction
2.
Experimental Setup
3.
Results
4.
Conclusions and future works
3
/17
Fibre
-
suspension flow
•
Fluid motion in papermaking process affects
quality of paper
–
Clarifying and controlling the flow is consistent
way to increase quality of paper
•
Studying in practical condition is necessary
–
Contraction and expansion of the flow
–
Steady and unsteady flow
4
/17
Nuclear Magnetic Resonance Imaging
(NMRI)
for flow measurement
•
Protons in fluid are traced
–
Non
-
invasive flow measurement method
–
Not adversely affected by optical
opaqueness
•
Local velocities of fluid are measured
by phase encode imaging
5
/17
Target and objective of the study
Target
Objective
Fibre
-
suspension flow in a pipe
through a sudden contraction and expansion
Obtaining velocity profiles using MRI
and determining the effect of the pulp fibre
6
/17
Experimental Setup
7
/17
Experimental setup
Magnet
Contraction
Pump
Flow meter
P
M
8
/17
Experimental conditions
O
x
r
175 [mm]
130 [mm]
100 [mm]
D
d
Diameter of the pipe
:
D
=45 [mm]
Diameter of the contraction
:
d
= 23 [mm]
Bulk velocity
:
U
= 78.6 [mm / s]
Flow
U
3
10
5
.
3
UD
Re
Bulk Reynolds number
:
Fraction of fibre (Softwood)
: 0, 0.5, 1.0 wt %
9
/17
Results
10
/17
Vertical direction
g
1.0% pulp
0% pulp
0.5% pulp
Velocity profile
at upstream (
x
=
-
130)
x
O
130
100
Flow
Horizontal direction
Plug flow
Turbulent flow
Laminar flow
–
Paper pulp stabilizes the flow and forms plug flow
–
Paper pulp makes sedimentation
11
/17
Velocity profile
around contraction
(
x
=
-
105,
-
70, Horizontal)
x
O
70
Flow
x
=
-
105
x
=
-
70
105
1.0% pulp
0% pulp
0.5% pulp
1.0% pulp
0% pulp
0.5% pulp
12
/17
30
Velocity profile
around expansion
(
x
=
-
30, 30, Horizontal)
x
O
30
Flow
x
=
-
30
x
=30
1.0% pulp
0% pulp
0.5% pulp
1.0% pulp
0% pulp
0.5% pulp
13
/17
1.0% pulp
0% pulp
0.5% pulp
g
1.0% pulp
0% pulp
0.5% pulp
Effect of sedimentation
30
x
O
130
Flow
x
=30 (Horizontal)
x
=
-
130 (Vertical)
Upstream velocity profile might affect downstream
Flow of 0.5% suspension has
remarkable velocity profile
14
/17
Velocity profile at
downstream (
x
=120,
Horizontal)
x
=120
x
O
120
Flow
1.0% pulp
0% pulp
0.5% pulp
15
/17
Effect of turbulence
MRI measurement in unsteady flow is still
challenging
x
O
120
Flow
0% pulp (Turbulent)
Acquired signal at
x
=120
1.0% pulp (Laminar)
Turbulence attenuates signal
intensity
16
/17
Conclusions and Future works
17
/17
Conclusions and future works
MRI measurement of pulp suspension flow
in a sudden contraction and expansion has been
performed
•
Conclusions
–
Pulp in water behaves like increasing of viscosity
before it forms plug flow
–
Sedimentation affects velocity profile
•
Future works
–
Improving MRI protocols
–
Coupling between horizontal and vertical direction
18
/17
Thank you for your attention
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