The Application Basic Research On The First Order Buoyancy Principle Of Magnetic Fluid

As a new type of functional material,magnetic fluid can present a lot of special properties under the effect of magnetic field.The buoyancy principle of magnetic fluid is one of the most important characteristics.Under the affection of the external magnetic field,the nonmagnetic object immersed in magnetic fluid can be suspended,so the first order buoyancy principle of the magnetic fluid plays an important part in the applications of magnetic fluid absorber,sensor and actuator.In this paper,the factors of affecting the first order buoyancy of magnetic fluid are studied through theoretical deduction,finite element simulation and experimental methods.And the affection mechanism of the first order buoyancy is analyzed.The main work of this thesis is as follows:(1)The calculation model for magnetic fluid absorber,sensor and actuator is established.The first order buoyancy formula of magnetic fluid for this model is derived by using Navier-Stokes and Bernoulli equations.The calculation model of magnetic field of the cylindrical permanent magnet is established,and the formula of magnetic field in space is derived.The magnetization mechanism of magnetic fluid is analyzed,and the magnetization curve equation of magnetic fluid is described by Langevin function.(2)A two-dimensional axisymmetric model and a three-dimensional non-axisymmetric model of the first order buoyancy of magnetic fluid are established.On this basis,the first order buoyancy experienced by a nonmagnetic object immersed in magnetic fluid under different conditions is simulated by finite element method.Establishing A mathematical model for calculating the magnetic field of cylindrical permanent magnet,and the magnetic field distribution of cylindrical permanent magnet in space is calculated by finite element method.(3)The experimental scheme for measuring the first order buoyancy of magnetic fluid is proposed and the experimental platform is set up.By comparing the experimental results and simulation results,the accuracy of finite element simulation is verified.(4)By analyzing the simulation results and experimental results,we can get the factors that affect the first order buoyancy of magnetic fluid.When a nonmagnetic object is completely immersed in magnetic fluid,the factors affecting the first buoyancy are the relative permeability of the magnetic fluid,the position of the nonmagnetic object in the container,and the shape of the nonmagnetic object.When a nonmagnetic object is not completely immersed in magnetic fluid,the first order buoyancy is related to the amount of magnetic fluid injected.