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Dynami Response of Magneto-Rheologial Fluid Seal
with Fluid/Wall Interations
1
1
2
3
H. Nishiyama , H. Takana , K. Mizuki , H. Weisbeker , and S. Odenbah
1
2
3
3
Institute of Fluid Siene, Tohoku University, Sendai, Japan
Graduate Shool of Engineering, Tohoku University, Sendai, Japan
Tehnishe Universitat Dresden, Dresden, Germany
Introdution
MR seal is reently onsidered to be one of
the most promising devie and is now expeted to expand its appliation not only to
industrial devies but to medial or safety
devies, suh as blood ow sealing or steam
shut-down valve.
In this study, rstly, the eet of wall
roughness on rheologial properties of MRF132DG was experimentally analyzed. Then,
experimental analysis on dynami response
of MR uid seal in pressure mode was onduted. Furthermore, MR sealing harateristis in a viso-elasti hannel will be investigated with onsidering uid/wall interations. The objetive of this study is to
provide the fundamental data for the novel
appliation of MR seal to a medial or safety
devies.
Fig.1 Shemati illustration of experimental setup.
Experimental Analysis
In this study, MRF-132DG manufatured
by LORD Corporation are used as a test
sample. The typial properties of MRF132DG oÆially released by LORD Corp.
are listed in Table 1.
Figure 1 shows the shemati illustration of
pressure driven MR uid hannel ow system[1℄. In this system, MR uid is driven
by piston ontrolled by a stepping motor. A
Table 1 Typial Properties of
Partile Material
Base Oil
Visosity, Pa s 40 C
Density, g=m3
Solids Content by Weight %
Operating Temperature, C
MRF-132DG.
Iron
Hydroarbon
0.092 0.015
2.98-3.18
0.8098
-40 to +130
Fig.2 Shear stress as a funtion of shear rate at
various magneti eld intensity using
smooth smooth one (Rz = 0.5) and the rough
one (Rz = 4.5) in rotating shear mode.
MR hannel is made of arylis with retangular ross setion of 10 mm 10 mm.
Time evolutions of pressure distributions are
laried experimentally. Magneti eld is
applied perpendiular to the ow as shown
in Fig.1.
Results and Disussion
Figure 2 shows shear stress measured by
one-plate rheometer with smooth one (Rz
= 0.5) and the rough one (Rz = 4.5) in
rotating shear mode at various magneti
eld intensity. The rough one provides
higher stati yield stress espeially for ef-
0
0
pu
pu (B = 0)
pd
10 20 30 40 50
t (s)
vpiston = 0.5 mm/s
200
(A)
100
pseal
0
0
pMR (kPa)
50
vpiston = 2.0 mm/s
B = 800 G
(B) (C)
0
magnet off
pd
pu
50
vpiston = 4.9 mm/s
200 B = 1200 G
(A) (B)
(C)
0
100
0
10 20 30 40 50
t (s)
0
pseal magnet off
pu
pd
10 20 30 40 50
t (s)
300
pMR (kPa)
magnet off
pd
300
10 20 30 40 50
t (s)
vpiston = 2.0 mm/s
50
vpiston = 4.9 mm/s
200
B = 800 G 0
(A) (B) (C)
100
pseal
0
0
pu magnet off
dpiston (mm)
(C)
magnet off
dpiston (mm)
(A)(B )
100
pu
300
dpiston (mm)
0
0
(C)
100
0
0
50
200
pseal
pMR (kPa)
pu ( B = 0) pd
10 20 30 40 50
t (s)
vpiston = 0.5 mm/s
B = 800 G
B = 1200 G
200
(A) (B )
50
pseal
pMR (kPa)
300
(C)
pu
vpiston = 2.0 mm/s
dpiston (mm)
(A) (B )
100
pseal
300
dpiston (mm)
0
200
0
0
pMR (kPa)
50
vpiston = 0.5 mm/s
B = 1200 G
dpiston (mm)
pMR (kPa)
300
pd
10 20 30 40 50
t (s)
vpiston = 4.9 mm/s
Fig.3 Time evolutions of internal pressure and piston displaement at various piston speed and
magneti ux density.
fetive magneti eld intensity larger than
2.64 kA/m.
Figure 3 shows the time evolutions of hannel pressures pMR and piston displaement
dpiston at piston head speed of 0.5 mm/s, 2.0
mm/s, and 4.9 mm/s for applied magneti
ux density of of 800 G and 1200 G, respetively. Piston starts to move after 3 minutes in resting state under a magneti eld
for MR seal formation. pu and pd represent
pressures at the inlet of hannel and downstream of MR seal, respetively as indiated
in Fig.1.
In region (A) in Fig.3, inlet pressure inreases rapidly with the movement of piston. Then, MR seal starts to breakdown
when the inlet pressure exeeds the endurane pressure of MR seal, pseal . After the
seal break down, inrease of upstream and
downstream pressure is suppressed as shown
in region (B). After stopping the piston,
although both upstream and downstream
pressure dereases rapidly, the pressure differene still exists due to the reformation of
lusters near magnet as shown in region (C).
With inreasing piston head veloity, the
time before seal breakdown is shortened and
seal endurane pressure inreases. The inrease in seal endurane pressure is due to
the robust resistane of luster and a higher
loal onentration of magneti partiles at
the upstream of MR seal with inreasing piston speed.
Conlusion
The eet of wall roughness on rheologial properties and the dynami response
of MR seal in pressure mode were made
lear through the experimental analysis using MRF-132DG as a test sample. The MR
sealing performane are strongly aeted
both by applied magneti eld intensity and
piston veloity due to a higher loal luster
agglomeration at the upstream of the magnet.
The future study will larify how the hannel ongurations or wall onditions, suh
as the viso-elastisity, or permeability, aet
MR sealing harateristis and ow rate.
Aknowledgments
The present study was partly supported by a
Grant-in-aid for Exploratory Researh from
the Japan Soiety for Promotion of Siene.
Authors would like to thank K. Katagiri and
T. Nakajima from Institute of Fluid Siene,
Tohoku University for their tehnial support.
Referene
[1℄ Nishiyama, H. et al., AIP Pro., Vol.982, Complex Systems(2008), pp.592-597.