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Research Papers

Magnetorheological Fluid Flow in Microchannels

[+] Author and Article Information
Joseph Whiteley, Xiaojie Wang

Department of Mechanical Engineering, Composite and Intelligent Materials Laboratory, University of Nevada, Reno, NV 89557

Faramarz Gordaninejad1

Department of Mechanical Engineering, Composite and Intelligent Materials Laboratory, University of Nevada, Reno, NV 89557faramarz@unr.edu

1

Corresponding author.

J. Appl. Mech 77(4), 041011 (Apr 14, 2010) (10 pages) doi:10.1115/1.4000922 History: Received June 27, 2009; Revised December 10, 2009; Published April 14, 2010; Online April 14, 2010

This study presents experimental results on the flow of magnetorheological grease (MRG) through microchannels. MR materials flowing through microchannels create microvalves. The flow is controlled by injecting the MRG through microchannels with controlled adjustable rates. To study the effect of different channel diameters and surface roughnesses, microchannels made of stainless steel, PEEK, and fused silica materials with nominal internal diameters ranging from 1 mm to 0.075 mm (75μm) are tested. A magnetic field is applied perpendicular to the microchannel flow and is controlled by an input electric current. The pressure drop of the flow is measured across the length of the microchannels. The dynamic pressure drop range and surface roughness effects are also discussed. The Herschel–Bulkley model for non-Newtonian fluid flow is employed to the experimental results with good agreement. The results show a significant pressure drop for different magnetic field strengths.

Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 22

Pressure gradient versus flow rate across 114 μm stainless steel microchannel

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Figure 23

Pressure gradient versus flow rate across 123 μm PEEK microchannel

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Figure 24

Yield stress versus magnetic field strength for large stainless steel and PEEK channels

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Figure 25

Yield stress versus magnetic field strength for small stainless steel, PEEK, and PEEKsil™ microchannels

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Figure 1

Schematic of the experimental setup

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Figure 2

Raw pressure drop data recorded for 511 μm ID stainless steel channel for step changing flow rate at different applied magnetic fields

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Figure 3

Raw pressure drop data recorded for PEEK microchannels with a constant MRG flow rate of 0.125 ml/min

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Figure 4

Shear stress versus shear rate for the MRG using a plate-plate measurement method

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Figure 5

Shear yield stress versus applied magnetic field for comparing MRG to Lord MRF-132AD using the Bingham model

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Figure 6

Shear stress and viscosity versus shear rate for UNR MRG with no magnetic field applied using a cone-plate measurement method

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Figure 7

Change in pressure drop versus change in flow rate in PEEKsil microchannels for the base grease

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Figure 8

Approximate length of influence from the magnetic field compared with the total microchannel length. Dimensions are in millimeters (inches).

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Figure 9

Flow of MR suspension through a circular cross section (3,13)

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Figure 10

Pressure gradient versus flow rate across 1008 μm stainless steel microchannel

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Figure 11

Pressure gradient versus flow rate across 985 μm PEEK microchannel

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Figure 12

Pressure gradient versus flow rate across 787 μm stainless steel microchannel

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Figure 13

Pressure gradient versus flow rate across 780 μm PEEK microchannel

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Figure 14

Pressure gradient versus flow rate across 511 μm stainless steel microchannel

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Figure 15

Pressure gradient versus flow rate across 523 μm PEEK microchannel

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Figure 16

Pressure gradient versus flow rate across 250 μm stainless steel microchannel

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Figure 17

Pressure gradient versus flow rate across 270 μm PEEK microchannel

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Figure 18

Pressure gradient versus flow rate across 158 μm stainless steel microchannel

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Figure 19

Pressure gradient versus flow rate across 149 μm PEEK microchannel

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Figure 20

Pressure gradient versus flow rate across 142 μm PEEKsil™ microchannel

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Figure 21

Pressure gradient versus flow rate across 134 μm PEEK microchannel

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Figure 26

Comparison of the fitted value of the yield stresses using Eq. 7 for microchannel flow with the yield stresses obtained from parallel-plate shear rheometer under various magnetic fields

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