MRI Measurements of Fibre-

choppedspleenMécanique

22 févr. 2014 (il y a 3 années et 3 mois)

82 vue(s)

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





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