The Design Of Viscometer For Ferrofluid And The Experiments And Simulation Of Applied Magnetic Field

Due to its special rheological properties, ferrofluid as a new type of smart material is widely used in many fields. The viscosity is an important parameter of the fluid rheology. Especially in the magnetic field, the rheological properties of ferrofluid changes greatly, and the viscosity increases by orders of magnitude. For different applied magnetic field, there are different rules of the variation of viscosity. In order to explore the rules, it requires accurate viscosity measurement device when it’s in magnetic field. Viscometers in the business application are designed for conventional fluid, and if they are used in a magnetic field, there would be some matters that were ignored such as the poor shielding, the small measuring range and the low digital level. So, it could not be used for dynamic multi-parameter measurement which would directly affect the accuracy of the test result. A special device for viscosity measurement must be designed to solve, these problems.By deeply understanding the composition and the microstructure rheological mechanism of ferrofluid, analyzing the classification and rheology law of fluid, the applicable fluid mathematic model of ferrofluid was established. Combining with the low viscosity of the solid phase calculation theory, the ferrofluid’s initial viscosity and the calculation formulas of viscosity in an applied magnetic field were obtained on the basis of the model, and then the factors impacting on viscosity were determined. Based on the analysis of existing conventional viscosity measurement methods, rotation method was finally chosen for viscosity measurement from comparing advantages with disadvantages in the methods and the scope of application. And a mathematical model of the double-cylinder type rotary viscosity measurement was constructed to determine the parameters for the test requires.The applied magnetic field is a key influence factor to the ferrofluid viscosity. Parallel dipolar electromagnet was a generating device of the applied magnetic field, and the simulation of its three-dimensional (3D) magnetic field distribution was carried out. The simulation results were verified by the experimental measurement, and the magnetic field spatial distribution of electromagnet work range was obtained. A cup of ferrofluid was placed in the electromagnet work range, and ferrofluid’s magnetic field distribution in the magnetic field was simulated with the ANSYS software. With experimental measurement to verify the correctness of the simulation results, the magnetic field distribution of ferrofluid in the cylinder area was obtained. Preparation had been made for the study of the relationship between ferrfluid viscosity and the variation tendency of magnetic field. Finally, some measures such as anti-magnetic and anti-jamming improvement were taken against the deficiencies of the existing viscometers. Adopted the highly integrated torque sensor, the temperature and magnetic field would have been detected, and then the conducting research in the multiple factors affecting variation of the ferrofluid viscosity would have been realized. By adding an external data storage module in the hardware circuit to call the measurement data and combining software programming, the dynamic ferrofluid viscosity would have been analyzed. Further more, the structure and signal processing system diagram of the viscometer had been designed which prepared the way for building the subsequent workbench.