Delft University of Technology Magnetic fluid bearings & seals Methods, design & application

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Delft University of Technology

Magnetic fluid bearings & seals

Methods, design & application

Lampaert, S.G.E. DOI 10.4233/uuid:361ba18e-298a-483c-bfb9-0528a4ee6119 Publication date 2020 Document Version Final published version Citation (APA)

Lampaert, S. G. E. (2020). Magnetic fluid bearings & seals: Methods, design & application. https://doi.org/10.4233/uuid:361ba18e-298a-483c-bfb9-0528a4ee6119

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r z x p A r L F _h r i p p R in r i H o H M p V r z x L F h p R M

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17th_{EDF/Pprime Workshop:} _{Paris Saclay, October 4, 2018}

“Green sealing”

a Department of Precision and Microsystems Engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft

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“Green sealing”

Fig 1 The seal is first a) at equilibruim. Then FF is added b) to the first seal, moving the interface. Magnetic forces c) of the second magnet become more prevalent on the fluid, pulling excess towards it. Finally equilibrium restores d) with the excess fluid now on the second magnet

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“Green sealing”

Fig 2 A cut-through of the FFP 02. Colours and tags are used to differentiate between the different components.

Fig 3 Top image is A cutthrough of the FFP 02. Colours and tags are used to differentiate between the different components. Numbers correspond with the bottom image. Here, the pressure chamber 1 is fed by the inlet 2. The inlet of the FF 3 is connected to the syringe 4, used as FF resevoir and pump. A relative pressure sensor 6 is connected to a data proccessor 5. The motor 7 drives the setup.

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“Green sealing”

Fig 4 Magnetic field lines of the 2D model. Half of the cuttrough has been modelled because of symmetry. Dotted line represents the symmetry line at the center of the shaft. The vertical black line represents the gap of the seal.

Fig 5 Graphs of the magnetic intesity at the top and bottom surfaces in the gap of the seal. Peaks correspond to the edges of the magnets, shown in red. Height is measured from the surface of the magnet.

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“Green sealing”

Tab 1 Magnetization values from the FEM model for calculating the theoretical maximum pressure.

Fig 6 An example of three datasets used in calculating the average of . The sharp drop is the result of a leak of the seal. The pressure rise differsbecause of the fact that the presure valve is operated manually.

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“Green sealing”

Fig 7 At each speed interval a leak test was carried out, resulting in the . The slope indicates the decreases with speed increase.

Fig 8 Set up is pressurized to and is run at different speeds where after a certain time (blue area) FF is added to the seal. The rising of the pressure is due to the heating of the setup by viscous friction.

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“Green sealing”

Fig 9 Starting at 0 RPM, the speed is increased by increments of 1000 every 30 seconds until 6000$ RPM. A slight negative slope is visible.

Fig 10 At the sub-critical pressure the speed is increased to $6000$ RPM. The speed is then maintained until failure of the seal.

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“Green sealing”

Fig 11 Set up is filled with water and pressurized to 0.5 . At certain moments (solid line) speed is increased, and inbetween (dotted line) FF is added to the seal. At 3000 RPM the seal fails at the moment of FF addition.

et al. Artif. Organs

J. Magn. Magn. Mater.

J. Artif. Organs

IOP Conf. Ser. Earth Environ. Sci.

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18th_{EDF/Pprime Workshop:} _{EDF Lab Paris-Saclay, October 10 & 11, 2019}

“Challenges in Sliding Bearing Technologies for Clean and Low Carbon Energy Applications”

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18th_{EDF/Pprime Workshop: EDF Lab Paris-Saclay, October 10 & 11, 2019}

Fig 1 – Formation of chain-like agglomerates in an MR fluid when subjected to a magnetic field.

Fig 2 - Shear mode for a Newtonian fluid (top) and an MR fluid (bottom) between two parallel surfaces where one surface is moving relative to the other surface.

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Fig 3 - The step geometry (top graph) leads to a saw tooth pressure profile (lower graph). The combination of a magnetic field and MRF (middle graph) also produces a similar geometry and therefore

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Fig 4 - Different models where the shear stress versus the shear rate is shown. Here H2 > H1 and m is the regularization parameter.

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Tab 2 - Normalized parameters used for simulating an MR fluid in shear mode.

Tab 3 - Normalized parameters used for simulating the MR fluid MRF140CG

Fig 5 - An environment representing a bearing consisting of 4 layers: 2 layers of metal, a layer containing square magnets and metal blocks, and a layer of MR fluid. Here the top metal surface represents the

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Fig 6 - The velocity profiles for a Poiseuille flow of the MR fluid for different yield stresses.

Fig 7 - The apparent viscosity for a Poiseuille flow of the MR fluid for different yield stresses.

Fig 8 - The absolute normalized shear stress for a Poiseuille flow in the MR fluid for different yield stresses.

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Fig 9 - The normalized shear rate for a Poiseuille flow in the MR fluid for different yield stresses.

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Fig 11 - The apparent viscosity of the MR fluid for different velocities of the moving wall.

Fig 12 - The normalized shear stress in the MR fluid for velocities of the moving wall. Also the yield stress in the fluid is plotted here, this one is the same for every velocity

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Fig 14 - Simulated array of magnets and metal blocks.

Fig 15 - Solid part created in the middle of the length of the channel at a velocity for the moving wall of 0.3.

Fig 16 - The velocity profiles of the MR fluid with a solid part in the middle of the length of the channel for different velocities of the moving wall.

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Fig 17 - The apparent viscosity in the MR fluid with a solid part in the middle of the length of the channel for different velocities of the moving wall.

Fig 18 - The normalized shear stress in the MR fluid with a solid part in the middle of the length of the channel for different velocities of the moving wall.

Fig 19 - The normalized shear rate in the MR fluid with a solid part in the middle of the length of the channel for different velocities of the moving wall.

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Fig 20 - The normalized pressure distribution in the MR fluid with a solid part in the middle of the length of the channel for different velocities of the moving wall.

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