磁流体在磁场中的粘度测试研究

Experimental Investigation on Viscosity of Magnetic Fluid in Magnetic Field

针对磁流体在磁场中粘度测试的特殊性,研制了一种新型的旋转法磁流体粘度测试实验台,该实验台可通过测试带动工作气隙内磁流体作旋转剪切运动所需的力矩来推算得出磁流体的粘度,满足磁流体在磁场中的粘度测试要求。利用所设计的实验台对矿物油基Fe3O4磁流体的粘度进行了测试,研究了外加磁场、温度及磁流体中磁性颗粒含量对其粘度的影响规律。结果表明:磁流体的粘度随着外加磁场强度的增加而增大,当磁场强度增大到一定程度时,其粘度变化逐渐趋缓;随着温度的升高,磁流体的粘度呈不断下降趋势,在有外加磁场作用情况下,其粘度下降的幅度要远大于无外加磁场作用的情况;随着磁流体中所含磁性颗粒质量分数的增加,其粘度逐渐增大,当磁性颗粒质量分数小于30%时,粘度增加缓慢,但当质量分数超过30%以后,粘度则急剧增大。

A new kind of viscometer was constructed according to the particularity of measuring viscosity of magnetic fluids under magnetic field, in which, the viscosity of magnetic fluids was obtained by the torque to drive it in shearing motion within the working clearance. Viscosities of mineral oil-based Fe304 magnetic fluids were measured using the viscometer, and the influences of applied magnetic field, temperature, and concentration of magnetic particles on the viscosity of the magnetic fluids were investigated. The results show that the viscosity of magnetic fluid increases gradually as the applied magnetic field increases, but the increase slows down while the applied magnetic field exceeds a certain value. The viscosity of magnetic fluid decreases as the temperature goes up, but the extent of decreasing in the applied magnetic field is larger than that not in. The viscosity of magnetic fluids increases as the concentration of magnetic particles rises, it increases sharply while the concentration excess 30%.