Masato Hirota

MRI Measurements of Fibre-Suspension Flow in a SuddenContraction/Expansion

FP1005 & SIG43 Workshop NTNU, Trondheim 24-26 October 2012

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Outline

1. Introduction2. Experimental Setup3. Results4. Conclusions and future works

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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

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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

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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

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Experimental Setup

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Experimental setup

Magnet

Contraction

Pump

Flow meter

ＰＭ

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Experimental conditions

Ox

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

3105.3

UDReBulk Reynolds number :

Fraction of fibre (Softwood) : 0, 0.5, 1.0 wt %

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Results

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Vertical direction

g1.0% pulp

0% pulp

0.5% pulp

Velocity profile at upstream (x=-130)

xO

130100

Flow

Horizontal direction

Plug flow

Turbulent flow

Laminar flow

–Paper pulp stabilizes the flow and forms plug flow–Paper pulp makes sedimentation

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Velocity profile around contraction (x=-105, -70, Horizontal)

xO

70

Flow

x=-105 x=-70

105

1.0% pulp

0% pulp

0.5% pulp

1.0% pulp

0% pulp

0.5% pulp

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30

Velocity profile around expansion (x=-30, 30, Horizontal)

xO

30

Flow

x=-30 x=30

1.0% pulp

0% pulp

0.5% pulp

1.0% pulp

0% pulp

0.5% pulp

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1.0% pulp

0% pulp

0.5% pulp

g1.0% pulp

0% pulp

0.5% pulp

Effect of sedimentation

30

xO

130

Flow

x=30 (Horizontal)x=-130 (Vertical)

Upstream velocity profile might affect downstream

Flow of 0.5% suspension has remarkable velocity profile

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Velocity profile at downstream (x=120, Horizontal)

x=120

xO

120

Flow

1.0% pulp

0% pulp

0.5% pulp

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Effect of turbulence

MRI measurement in unsteady flow is still challenging

xO

120

Flow

0% pulp (Turbulent)

Acquired signal at x=120

1.0% pulp (Laminar)

Turbulence attenuates signal intensity

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Conclusions and Future works

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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

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Thank you for your attention