密封间隙内纳米磁性流体与被密封液体相对运动速度分析
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摘要
在磁性流体动密封液体中,不相溶的两液体相对运动速度是影响其界面稳定性的主要因素。应用流体运动理论,结合MATLAB仿真,确定了两液体沿旋转轴径向速度分布规律和相对运动速度差的大小。研究结果表明:影响该相对运动速度的因素主要是磁性流体的屈服应力、粘性系数、非牛顿影响系数、旋转轴转速和径向半径,其中非牛顿影响系数和转速最明显,而轴径影响很小;磁性流体与被密封液体相对运动速度差沿轴径呈抛物线分布,说明应用于密封液体的磁性流体具有相应的表观粘度,就能达到与被密封液体的相对运动速度差在界面稳定的阈值范围内。这对深入研究磁性流体与被密封液体的界面稳定性判据及外加磁场的设计具有重要的指导意义。
In the dynamic sealing liquid with magnetic fluid, the relative speed of two non-dissolve liquid is the main factor that affects the interfacial stability. By motion theory and MATLAB software simulation, the radial velocity distribution of the two liquids along the rotation axis and the relative motion velocity difference can be determined. Current research shows that the main influential factors on the relative speed is the yield stress, thecoefficient of viscosity, the non-Newtonian influence coefficient, the rotational speed and radial radius of axis of magnetic fluid. Among them, effects of the non-Newtonian influence coefficient and rotational speed are the most obvious, and the effect of diameter of axle on relative velocity is little. The relative speed difference along the diameter of axle between the magnetic fluid and sealed liquid reveals parabolic distribution, so there is an apparent viscosity for magnetic fluid applied to seal liquid, the viscosity can make the relative speed difference within the scope of threshold for interface stability. These results may provide an important guiding significance for the further study of interfacial stability criterion and the design of the magnetic field to magnetic fluid and the sealed liquid.
In the dynamic sealing liquid with magnetic fluid, the relative speed of two non-dissolve liquid is the main factor that affects the interfacial stability. By motion theory and MATLAB software simulation, the radial velocity distribution of the two liquids along the rotation axis and the relative motion velocity difference can be determined. Current research shows that the main influential factors on the relative speed is the yield stress, thecoefficient of viscosity, the non-Newtonian influence coefficient, the rotational speed and radial radius of axis of magnetic fluid. Among them, effects of the non-Newtonian influence coefficient and rotational speed are the most obvious, and the effect of diameter of axle on relative velocity is little. The relative speed difference along the diameter of axle between the magnetic fluid and sealed liquid reveals parabolic distribution, so there is an apparent viscosity for magnetic fluid applied to seal liquid, the viscosity can make the relative speed difference within the scope of threshold for interface stability. These results may provide an important guiding significance for the further study of interfacial stability criterion and the design of the magnetic field to magnetic fluid and the sealed liquid.
引文
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[2]FENG Shicai,CHEN Qidong.Analysis on non-Newtonian characteristics for nano magnetic fluid[J].Procedia engineering,2017,174:1208-1214.
[3]COWLEY M D,ROSENSWEIG R E.The intefacial stability of a ferromagnetic fluid[J].Journal of fluid mechanics,1967,30(4):671-688.
[4]李文昌.磁流体密封润滑研究[J].北京化工学报,1993,20(1):25-28.(LI Wenchang.Study on magnetic fluid sealing to prevent lubricating from leakage[J].Journal of Beijing institute of chemical technology,1993,20(1):25-28(in Chinese)).
[5]王虎军,李德才,何新智.转轴转速对磁流体液体动密封耐压能力影响的实验研究[J].真空科学与技术学报,2016,36(8):945-949.(WANG Hujun,LI Decai,HE Xinzhi.Effect of rotation speed on failure-pressure of liquid sealed with magnetic fluid[J].Chinese journal of vacuum science and technology,2016,36(8):945-949(in Chinese)).
[6]YOSHINORI M,TETSUYA Y,WATARU N.A magnetic fluid seal for rotary blood pumps:behaviors of magnetic fluids in a magnetic fluid seal[J].Bio-medical materials and engineering,2013,23(1/2):63-74.
[7]封士彩,刘书进,刘同冈,等.纳米磁流体在机械密封领域的研究现状及发展[J].润滑与密封,2004(3):127-131.(FENG Shicai,LIUShujin,LIU Tonggang,et al.Researching on present situation and development of nano-magnetic fluid in mechanical seal[J].Lubrication engineering,2004(3):127-131(in Chinese)).
[8]封士彩.磁流体与被密封液体相对运动速度对其界面稳定性影响的研究[D].徐州:中国矿业大学,2004.(FENG Shicai.Research on interfacial stability affected by relative speed between magnetic fluid and sealed liquid[D].Xuzhou:China University of Mine and Technology,2004(in Chinese)).
[9]LóPEZ J,PINEDA H,BELLO D,et al.Study of liquid-gas two-phase flow in horizontal pipes using high speed filming and computational fluid dynamics[J].Experimental thermal and fluid science,2016,76:126-134.
[10]葛雄,张根广,颜婷,等.牛顿流体和非牛顿流体教学演示仪器的开发研究[J].现代科学仪器,2011(3):31-33.(GE Xiong,ZHANGGenguang,YAN Ting,et al.Teaching apparatus to demonstrate the differences between Newtonian fluid and non-Newtonian fluid[J].Modern scientific instruments,2011(3):31-33(in Chinese)).
[11]MITAMURA Y,YANO T,NAKAMURA W.A magnetic fluid seal for rotary blood pumps:behaviors of magnetic fluids in a magnetic fluid seal[J].Bio-medical materials and engineering,2013,23(1/2):63-74.