考虑气体稀薄效应和表面粗糙度，计算精密H型气体轴承的动态气浮力和接触力，分析气体轴承起动过程中转子的轴向运动行为和最小气膜厚度，讨论气浮面的螺旋槽数量和深度对气体轴承起动行为的影响。分析结果表明：随着转子转速增加，H型气体轴承的气浮力逐渐增大，转速约为200 r/min时气浮面与转子脱离接触；随着气浮面螺旋槽数量增加，气浮力增加、接触力降低，但槽数多于10时二者的变化量较小。考虑到微型螺旋槽的加工成本与效率，气浮面螺旋槽数量的优化值为10；随着螺旋槽深度增加，气浮力先增加后减小、接触力先降低后升高，深度为1.5 μm的螺旋槽产生最大气浮力和最小接触力，因此，精密H型轴承起动状态最优的螺旋槽深度为1.5μm。
The dynamic air bearing force and asperity contact force of precision H-type air bearings are calculated considering the effect of air rarefaction and surface roughness. The axial motion of the rotor and the minimum air film thickness is obtained. The effect of both the number and depth of spiral grooves on the startup behaviors of the air bearing is discussed. The results show that the air bearing force increases with an increase in the angular velocity of the rotor. When the angular velocity is about 200 r/min, the rotor fully separates with the air bearing surface. The increasing spiral groove number leads to an increase in the air bearing force and a decreased in the contact force. However, slight change in the air bearing force and contact force is generated when the groove number is over 10. Considering the cost and efficiency for manufacturing the spiral grooves, the optimal groove number of the air bearing is 10. With an increase in the groove depth, the air bearing force first increases and then decreases, while the asperity contact force first decreases and then increases. When the groove depth is 1.5 μm, a maximum air bearing force and a minimum asperity contact force are generated. Therefore, under the startup condition of the air bearing, the optimal groove depth is 1.5 μm.
[1] DUNFEE J D,SHAPIRO W. Start-stop testing of two self-acting air-lubricated micro spiral grooved thrust bearing coating[R]. Philadelphia:NASA-CR-134673,1974.
[2] HARP S R,SALANT R F. Analysis of mechanical seal behavior during transient operation[J]. Journal of Tribology-Transactions of the ASME,1998,120:191-197.
[3] RUAN B. Numerical modeling of dynamic sealing behaviors of spiral groove gas face seals[J]. Journal of Tribology-Transactions of the ASME,2002,124:186-195.
[4] FENG K,LI W J,XIE Y Q,et al. Theoretical analysis of the slip flow effect on gas-lubricated micro spherical spiral groove bearings for machinery gyroscope[J]. Microsystem Technologies,2016,22:387-399.
[5] 刘韧,王晓力. 微气体螺旋槽推力轴承润滑数值模拟[J]. 机械工程学报,2010,46(21):113-117. LIU Ren,WANG Xiaoli. Numerical predication of the performance of micro gas lubricated spiral groove thrust bearing[J]. Journal of Mechanical Engineering,2010,46(21):113-117.
[6] ZHANG X Q,WANG X L,LIU R,et al. Modeling and analysis of micro hybrid gas spiral-grooved thrust bearing for microengine[J]. Journal of Engineering for Gas Turbines and Power,2013,135:122508-1-8.
[7] FUKUI S,KANEKO R. A database for interpolation of Poiseuille flow-rates for high Knudsen number lubrication problems[J]. Journal of Tribology,1990,112(1):78-83.
[8] FUKUI S,KANEKO R. Analysis of flying characteristics of magnetic heads with ultra-thin spacings based on the Boltzmann equation[J]. IEEE Transactions on Magnetics,1988,24(6):2751-2753.
[9] ZHANG C,GU L,WANG J,et al. Effect of air rarefaction on the contact behaviors of air lubricated spiral groove thrust micro-bearings[J]. Tribology International,2017,111:167-175.
[10] 李治伟,周平,金洙吉. 粗糙薄层弹性体接触刚度分析[J]. 摩擦学学报,2015,35(1):53-58. LI Zhiwei,ZHOU Ping,JIN Zhuji. Contact stiffness analysis of rough thin elastomer[J]. Tribology,2015,35(1):53-58.
[11] WADDAD Y,MAGNIER V,DUFRÉNOY P,et al. A multiscale method for frictionless contact mechanics of rough surfaces[J]. Tribology International,2016,96:109-121.
[12] GREENWOOD J A,WILLIAMSON J B P. Contact of nominally flat surface[J]. Proceedings of the Royal Society of London A,1966,295:300-319.
[13] 陈奇,张振,刘鹏,等. 考虑摩擦的圆柱面切向接触刚度分形模型研究[J]. 机械工程学报,2016,52(23):168-175. CHEN Qi,ZHANG Zhen,LIU Peng,et al. Research on fractal model of tangential contact stiffness between cylindrical surfaces considering friction factors[J]. Journal of Mechanical Engineering,2016,52(23):168-175.
[14] 韩振华,石万凯,肖洋轶,等. 基于JKR模型的粗糙圆柱表面线黏着接触分析[J]. 机械工程学报,2016,52(19):117-122. HAN Zhenhua,SHI Wankai,XIAO Yangyi,et al. Adhesive contact analysis between rough surfaces based on JKR model[J]. Journal of Mechanical Engineering,2016,52(19):117-122.
[15] YUAN Y,GAN L,LIU K,et al. Elastoplastic contact mechanics model of rough surface based on fractal theory[J]. Chinese Journal of Mechanical Engineering,2017,30(1):207-215.
[16] ZHANG S,WANG W,ZHANG H,et al. The effect of hardness distribution by carburizing on the elastic-plastic contact performance[J]. Tribology International,2016,100:24-34.
[17] QIU Y,KHONSARI M M. Investigation of tribological behaviors of annular rings with spiral groove[J]. Tribology International,2011,44:1610-1619.
[18] HU S,HUANG W,LIU X,et al. Influence analysis of secondary O-ring seals in dynamic behavior of spiral groove gas face seals[J]. Chinese Journal of Mechanical Engineering,2016,29(3):507-514.
[19] JAMES D D,POTTER A F. Numerical analysis of the gas lubricated micro spiral grooved thrust bearing compressor[J]. Journal of Lubrication Technology,1967,89:439-444.
[20] BONNEAU D,HUITRIC J,TOURNERIE B. Finite element analysis of grooved gas thrust bearings and grooved gas face seals[J]. Journal of Tribology,1993,115(3):348-354.
[21] LIU Y,SHEN X,XU W. Numerical analysis of dynamic coefficients for gas film face seals[J]. Journal of Tribology,2002,124(4):743-754.
