摘要
为了研究应力偶效应和粗糙表面形貌效应对磁流体轴承润滑性能的双重影响,首先采用蒙特卡罗方法对具有高斯分布的随机粗糙表面进行表征,并与扫描电子显微镜下实际加工表面形貌图进行对比,同时基于Christensen随机模型和Stokes微连续理论,推导出随机广义非牛顿雷诺方程,通过有限差分法对微尺度条件下磁流体轴承进行数值模拟,分析横向和纵向粗糙模型下不同参数对磁流体轴承润滑特性的影响。结果表明:实际的工程粗糙表面具有各向异性;不同粗糙模型对承载性能的影响趋势与宽径比有关,当粗糙度参数为0.3,轴承宽径比为0.5时,纵向粗糙模型将使最大无量纲压力提升3.9%,而横向模型将会削弱压力水平;当宽径比增至2.0时,横向粗糙模型将使其提升5.7%,从而改善承载性能;动力参数、磁力系数以及应力偶参数的增加均能不同程度地增强液膜压力水平,其中后两者的增加将会使粗糙模型的影响效应显著增强,同时承载力增大且偏位角减小;当应力偶参数从0.2增至0.5时,粗糙模型对承载力的影响趋势随宽径比变化的分界点从1.70增至1.95。
In order to study the effects of couple stress and rough surface morphology effect on the lubrication performance of magnetic fluid bearing,the Monte-Carlo method was used to characterize the random surface roughness with Gaussian distribution,and compared with the actual surface morphology under scanning electronic microscope,the stochastic generalized Reynolds equation was deduced by the Christensen＇s stochastic model and Stokes micro-continum theory,the finite difference method was used to simulate the magnetic fluid bearing under the micro-scale condition,and the effects of different parameters on the lubrication characteristics under the transverse and longitudinal rough models were analyzed. The results show that the actual rough surface of the project has anisotropy,the influence of different rough models on the load carrying performance is related to the aspect ratio,when the roughness parameter is 0.3,and the aspect ratio is 0.5,the longitudinal rough model will increase the maximum dimensionless pressure by 3.9%,while the transverse model will weaken the pressure level. When the aspect ratio increased to 2.0,the transverse rough model will increase it by 5.7%,thus improving the load carrying performance. The increase of the dynamic parameters,magnetic coefficient and couple stress parameters can increase the pressure level in different degrees,and the increase of the latter two will significantly increase the effect of the rough models,while the bearing capacity increases and attitude angle decreases. When the couple stress parameter increases from 0.2 to 0.5,the demarcation point between the bearing capacity with the change of aspect ratio in the rough model will increase from 1.70 to 1.95.
作者
张宏
陈超
ZHANG Hong;CHEN Chao(School of Mechanical Engineering,Taiyuan University of Technology,Taiyuan 030024,Chin)
出处
《推进技术》
EI
CAS
CSCD
北大核心
2018年第7期1617-1625,共9页
Journal of Propulsion Technology
基金
山西省自然科学基金项目(201601D102028)
山西省研究生教育创新项目(2017SY030)
关键词
磁流体轴承
应力偶
粗糙表面
随机广义雷诺方程
润滑特性
Magnetic fluid bearing
Couple stress
Surface roughness
Stochastic generalized Reynolds equation
Lubrication performance
