磁流变阻尼器管道流动特性研究

磁流变阻尼器是一种应用广泛的磁流变器件,其利用磁流变液独特的磁流变效应的工作.然而,磁流变体阻尼器设计中,一般地将磁流变液作为粘性流体建立流动的力学模型,进行流动分析以及参数设计,这样设计的结果与实测出现了较大的误差.本文将磁流变体作为一种粘塑性流体,建立了描述磁流变液流动的力学场和电磁场耦合的流体动力学基本方程组,分析研究了磁流变阻尼器沿狭长管道流动的特征,为磁流变阻尼器的设计提供了可靠的理论基础.     

基于双粘本构模型的汽车磁流变液减振器阻尼特性分析

将磁流变液在环形阻尼通道的流动简化为无限宽平板间的准稳态流动,建立了磁流变液平板准静态流动方程,利用磁流变液的双粘本构模型、边界条件和相容条件,得出了磁流变液速度分布,并分析了不同粘度比对磁流变液的流动速度分布的影响,在给定活塞速度和环形通道的几何尺寸条件下,对汽车磁流变减振器的阻尼特性进行理论预测,并研究了磁流变液减振器的双粘阻尼特性.按照长安之星微型汽车前悬架的技术要求,设计和制作了微型汽车磁流变减振器,在山川减振器公司对此进行了台架试验研究,试验结果表明应用所提出的理论分析模型和设计原理是可行的.     

多级径向流动型磁流变液减振器理论与实验

针对轴向流动型磁流变液减振器有效阻尼通道短和磁场利用率不高的问题,提出一种多级径向流动型磁流变液减振器;建立了磁流变液径向流动控制方程,并对其进行了合理简化,采用双粘本构模型导出磁流变液径向流动速度的表达式;利用定积分法分析了磁流变液惯性效应对径向压力梯度影响;得出了基于准稳态与非稳态流动的磁流变液减振器阻尼力计算方法。为了验证理论分析的合理性,按照轨道车辆抗蛇行减振器的技术要求,设计制作了多级径向流动型磁流变液减振器,利用J95-I型油压减振器实验台对其进行了阻尼特性实验,比较了不同激励电流下的磁流变液减振器阻尼力的实验值与理论值。     

圆筒式磁流变离合器的设计分析

磁流变离合器是通过磁流变液的剪切应力传递转矩的器件.本文建立了圆筒式磁流变离合器的几何设计方法,得到了磁流变液传递的转矩和两圆筒间能产生磁流变效应的最小间隙的设计计算公式,为离合器的几何设计奠定了理论基础.研究结果表明:转矩可由外加磁场连续控制;选择磁饱和时高屈服应力和零磁场时低粘度的磁流变液材料,能使设计的离合器的尺寸小而紧凑.     

磁流变液及磁流变阻尼器特性浅析

磁流变技术是目前国内外研究的特点。本文对磁流变阻尼器的研究发展进行了介绍，重点论述了磁流变液及磁流变阻尼器的特性。     

离子液体基低粘高屈服应力磁流变液

基液是影响磁流变液性能的重要因素.与传统基液相比,离子液体的粘度适中、具有极性,能够作为制备新型磁流变液的基液.选用1-辛基-3-甲基咪唑四氟硼酸盐离子液体为基液,以羰基铁粉为分散相颗粒,制备颗粒体积分数为20％的磁流变液,并与传统硅油基磁流变液进行性能对比.流变学测试结果表明,在436 kA/m下离子液体基磁流变液的...     

磁流变液的特性研究

对以金属铁颗粒为主体的磁流变液的一般特性进行了研究。详细研究了材料的颗粒大小、形状、比例以及温度等对磁流变液特性的影响。研究了流体的屈服应力与磁场关系,剪切应力与磁场以及剪切速率的关系。实验发现,磁流变液出现磁饱和现象不仅与材料特性有关,而且与配比比例有关;剪切应力不仅与材料的颗粒大小有关,还与材料的制备工艺有关。     

磁流变液动密封实验研究

磁流变液是一种由铁磁性悬浮相、悬浮介质和添加剂组成的分散体材料,具有高的饱和磁化强度,在外磁场作用下能产生高的屈服应力,可用于旋转轴的较高压差密封.设计了一种旋转轴密封装置,该装置包括高性能的永磁体、导磁良好的极靴和旋转轴,注入自制的磁流变液,在轴转速8000r/min时能够密封的氢气压差达到0.3MPa.     

磁流变液温度特性研究

主要配制了温度稳定性能优异的磁流变液,并分析温度对磁流变液悬浮相、载液和添加剂的影响,研究了磁流变液的粘度-温度特性,该磁流变液在20～100℃温度范围内粘度稳定性能优良.测试了该磁流变液的阻尼器在不同温度下施加不同电流时的阻尼力特性,并初步探讨了磁流变液阻尼力的温度衰减性能.     

海冰的粘塑性蠕变模型

本文将粘塑性理论用于海冰荷载分析,并将现有的一维蠕变方程推广到二维形式,采用非线性有限元方法计算了作用在一单桩结构上的最大静冰力。     

斜拉索磁流变液阻尼器半主动振动控制系统的设计与应用

桥梁斜拉索是一种小阻尼、大柔度结构,在各种环境荷载作用下极易发生剧烈振动,因此迫切需要采取一定的措施来提高斜拉索的耐久性和安全性.本文针对山东滨州黄河公路大桥的减振需要,研究了怂基于磁流变液阻尼器的半主动振动控制系统的设计、材料与器件的性能实验以及现场振动控制实验.     

Analysis of the flow of an irregular viscous fluid between two revolving cylinders

We propose a mathematical model for the flow of an irregular viscous fluid between two revolving cylinders in a bipolar coordinate system. We present an analytic solution of the system of equations obtained, and we also obtain formulas for determining velocity fields, temperature fields, and energy characteristics.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 2, pp. 256–262, February, 1976.     

Natural convection flow of a non-Newtonian fluid between two concentric vertical cylinders

Summary The natural convection of a homogeneous incompressible fluid of grade three between two infinite concentric vertical cylinders is studied. We consider the effect of the non-Newtonian nature of the fluid on the skin friction and heat transfer. Some numerical experimentation is presented to show the effect on the velocity and temperature profiles as the dimensionless parameters are varied.     

多环形槽结构磁流变阻尼器的实验建模

对自行设计的、多环形槽结构磁流变阻尼器进行了理论分析与实验建模.该阻尼器的主要特点是在阻尼活塞周向表面上开有若干个矩形齿状环形槽,并且通过磁路设计,使流经阻尼通道处的磁流变液流动方向与其作用的磁力线方向垂直,用以增大阻尼力和阻尼力变化范围.然后从磁流变液的流变特性、电磁学的角度出发,利用修正了的非牛顿流体宾汉模型、结合实验数据,建立了该阻尼器的力学模型.利用该模型绘制和分析了外加磁场(通过施加电流实现)和阻尼力之间关系曲线,与实验结果较好吻合,从而证明了模型的正确性,为磁流变液阻尼器设计和性能预测提供了参考.     

Non-Newtonian flow between concentric cylinders calculated from thermophysical properties obtained from simulations

A study of the Weissenberg effect (rod climbing in a stirred system) based on nonequilibrium molecular dynamics (NEMD) is reported. Simulation results from a soft-sphere fluid are used to obtain a self-consistent free-surface profile of the fluid of finite compressibility undergoing Couette flow between concentric cylinders. A numerical procedure is then applied to calculate the height profile for a hypothetical fluid with thermophysical properties of the soft-sphere liquid and of a dense colloidal suspension. The height profile calculated is identified with shear thickening and the forms of the viscometric functions. The maximum climb occurs between the cylinders rather than at the inner cylinder.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Stability of power law fluid flow between rotating cylinders

The centrifugal instability of power law fluid flow when the fluid fills the gap between two rotating concentric cylinders of infinite length is addressed. The instability of the circular Couette flow is determined via linear stability analysis. In the narrow gap case, the critical Taylor number is determined analytically, while in the general gap case, a finite-difference numerical method is employed. The results are shown to be in agreement with existing theoretical and experimental findings. The super-critical flow is investigated by means of a weakly non-linear analysis method. The Taylor-vortex flow (the secondary stable flow) is obtained. The instability of this flow is determined as we present the critical Taylor number when the Taylor vortices begin to exhibit a waviness in the azimuth     

Viscoplastic Models in Simulation of High Strain-Rate Behavior of Materials

Some specific features of material deformation behavior under impulse loading are considered. Viscoplastic models of materials used in calculations and methods of dynamic testing used to determine their parameters are analyzed. Examples of practical problems are presented (penetration, explosion welding), in the solution of which one should consider the effects associated with high strain rates.     

MHD heat transfer in the flow between two coaxial cylinders

Summary Stealy flow of an incompressible electrically conducting fluid between, two coaxial cylinders composed of non-conducting materials, is considered in the presence of a uniform radial magnetic field. The flow is due to the relative motions of the cylinders parallel to their common axis. The cylinders are maintained at constant temperatures. Heat transfer rates from the cylinders are plotted graphically against the Hartmann number.With 1 Figure     

并列方柱升阻力的被动流动控制研究

研究了Re数为200的情况下小方柱对并列双方柱的流动控制.并列双方柱的间隔比为1.5D(其中D为大方柱的边长),控制小方柱放置在并列双方柱下游L/D=1.0-2.0的位置;数值模拟采用分裂格式的有限元方法.结果表明,放置在适当位置的小方柱不仅可以显著抑制并列双方柱的漩涡脱落,而且可以降低脉动升阻力.     

两并列方柱绕流相互干扰的数值研究

为了研究并列双方柱在不同间距比时气动力特性的干扰效应,采用刚性模型测压风洞试验的方法,通过改变两方柱之间的距离,得到了不同间距比下并列双方柱的风压系数、升力系数和阻力系数。结果表明：当间距比1.2≤L/D<2.5时,并列双方柱平均风压系数的干扰效应明显,且主要表现在内侧面,平均阻力系数和脉动升力系数的干扰效应表现为减小效应;当间距比L/D≥2.5时,并列双方柱的平均风压系数、平均阻力系数和脉动升力系数的干扰效应均不明显。