磁流体动密封流体摩擦功耗的确定

Study on Frictional Power Loss in Ferrofluids Sealing

铁磁流体中存在一个不平衡旋度Ω ≠ 12 rotv ,由此引起悬浮在顺磁性载液中的磁偶极矩为m 的磁粒子的旋转摩擦 ,其摩擦粘度系数为 ηr。原先以磁畴取向的磁粒子 ,在外磁场作用下 ,改变其方向需一个弛豫时间τ。在高速 (≥ 7m/s)下 ,磁流体内摩擦功耗热致使其粘度和粒子磁性能下降。以牛顿内摩擦模型由朗之万和纳维 -斯托克斯方程导出磁粒子的旋转摩擦功耗公式。实验验证公式符合实验工况。

A nonequilibrium vorticity Ω≠12rotv exists under stationary conditions in ferrofluids,so it causes a rotational frictional friction of magnetic particulars in the carrier liquids which determine the coefficient of rotational viscosity η r.There is a relaxation time τ changing from domain oriented to magnetic oriented.In high velocity(≥7m/s),inner friction hot leads a decrease of viscosity of the ferrofluids and a worse of magnetic particles property.Friction power loss formula is derivated from Newton inner fraction modular by Langevins formula and Navier-Stokes equation.It agrees with the experiments.