MRI Measurements of Fibre-

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