Papers by Keyword: Magnetic Fluid

Abstract: Convection in an internally heated magnetic fluid is analyzed for rigid – rigid and rigid – free boundary surfaces with zero temperature at top and no heat flux at the lower surface. Linear stability analysis is performed for a variety of internal heat source models and the corresponding Eigen value problem is solved by Chebyshev Pseudospectral method.

Abstract: During the test of DC(direct current) abrasive magnetic fluid technology,many bubbles and noises were generated near the graphite electrode , and the yellow green liquid was produced, which affected the further test.Through the study of graphite electrode, it was found that NaCl solution magnetic fluid produced hydrogen and chlorine gas after electrolysis. At the same time, chlorine gas dissolved in water to form yellow green liquid.The magnetic field of neodymium boron permanent magnet was equivalent to a mechanical stirring, which inhibited the production of chlorine gas.According to the difference of impressed current system, the abrasive magnetic fluid jet technology was divided into DC and AC(alternating current) .There was no electrode in AC abrasive magnetic fluid jet technology, so no gas or noise would be produced.The rotating magic ring permanent magnet produced alternating magnetic field, acting on the abrasive magnetic fluid to form an induced current.Under the action of the magnetic field, the electromagnetic force was applied to move along the circumferential direction to promote the motion of the abrasive magnetic fluid.

Abstract: Performance analysis of porous inclined slider bearing based on magnetite nanosuspension has been carried out to investigate the effects of slip parameter arising out of modeling. The expression for load carrying capacity has been derived analytically as a function of slip, magnetic, permeability and material parameters. Furthermore, the effect of an important term pertaining to the co-rotational derivative of magnetization is usually ignored by the researchers working on similar problems. However, as this term is expected to influence the load carrying capacity significantly, this paper investigates its effect on the bearing performance parameters under the present conditions. Besides, the effect of varying the inlet-outlet ratio has also been studied. It has been found that with an increase in the inlet-outlet ratio up to an optimum value, the load carrying capacity increases followed by a decreasing trend.

Abstract: Oxygen-free copper (OFC) is a popular material used for molds/dies in injection molding of plastic lens because of its high ductility, strong impact strength and good thermal conductivity. nanoprecision polishing is essential as the final process in its fabrication. For this purpose, a novel polishing method using magnetic compound fluid (MCF) slurry was proposed. In this article, the construction of an experimental rig to realize the proposed method was described at first. Then the effects of process parameters including MCF slurry composition, workpiece oscillation parameter f/A_p-p and clearance Δ between workpiece and MCF carrier on work-surface roughness and material removal were experimentally investigated. As a result, nanoprecision surface finish of OFC was successfully attained by polishing with MCF slurry and the optimum process parameters (f/A_p-p=30 Hz/4mm, Δ=0.6 mm with an MCF slurry (45wt.% of CIP, 12 wt.% of Al₂O₃ grain, 3 wt.% of α-cellulose, 40 wt.% of MF) for obtaining the smoothest work-surface were determined.

Abstract: Temperature dependence of the low-frequency complex magnetic susceptibility of magnetic colloid with paraffin as a dispersion medium has been studied. When interpreting the obtained results, the specific features of the magnetic moment relaxation of single-domain particles and the possibility of changing of relaxation mechanism from Neel to Brownian have been considered.

Abstract: The optical properties of colloidal solutions of nanosized magnetite particles in kerosene were studied by optical methods (birefringence and light scattering). The data on the birefringence kinetics in nonstationary magnetic fields is used to determine the size distribution of magnetite particles and aggregates. It is shown that the particle size distribution essentially depends on the type of magnetic moments of the particles and aggregates. Static and dynamic light scattering experiments confirm the conclusion about the existence of a significant fraction of nanoparticles in the form of aggregates with sizes of several tens of nanometers.

Abstract: We consider a heavy, incompressible, homogenous, isothermal magnetic fluid between two coaxial cylinders in case of wetting. There is a current-carrying straight wire on the axis of these cylinders. The magnetic fluid is immersed in a non-magnetic liquid with the same density (the case of hydroimponderability). We apply the Langevin law to describe a magnetic fluid magnetization. Using the general analytical solution for any axially symmetric shape of the magnetic fluid free surface in any axisymmetric magnetic field, we investigate the break-up and the rebuilding of the magnetic fluid bridge in case of wetting.

Abstract: In the present work we report the investigation of heat exchange processes at stationary boiling regime of magnetic fluid on a horizontal surface under magnetic field H ≤ 4.2 kA/m. In the presence of uniform magnetic field the specific thermal flow arriving to boiling magnetic fluid increases by 1.5 - 2 times. We offer the mechanism of magnetic field influence on heat exchange intensity in boiling magnetic fluid. The volume, shape and contact area of steam bubbles in horizontal heating surface in magnetic field is studied. The equation, connecting a specific thermal flow, magnetic field gradient and magnetic fluid magnetization in bubble boiling regime of magnetic fluid is written.

Abstract: A new kind of damper with magnetic fluid(MRF)/foam metal designed by us is introduced, and it’s damp model is established. Semi-active controlling shock absorber with the damper is designed, and it’s dynamic module is established. Fuzzy control on chatter system is designed by fuzzy controlling theory. Finally, simulation on it is done by matlab /simulink. It is shown that the control system can restrain the chatter very well.

Abstract: Thermo-physical properties of magnetic fluid were measured experimentally at various temperatures, in order to evaluate their temperature dependencies. Heat transfer by natural convection was also investigated in a horizontal enclosed rectangular container filled with the tested magnetic fluid. It was found that the heat transfer coefficient of the magnetic fluid keeps good agreement with the conventional heat-transfer correlation of natural convection heat transfer in a horizontal enclosed rectangular container by applying the values of thermo-physical properties obtained in the present work. Therefore, the measured thermo-physical properties are reliable and can be used as a thermo-physical database of the magnetic fluid.