摘要
为揭示静压气体推力轴承微幅自激振动的内在机理,采用大涡模拟(Large eddy simulation,LES)分析小孔节流静压气体轴承内气体流动特性。发现在节流孔出口附近的湍流区域内气体产生极其复杂的漩涡,气体压力和流速自漩涡中心向边缘逐渐变化,随着气体的流动漩涡不断产生和破裂,造成气膜内气体压力波动,导致承载能力快速改变,引起轴承产生微幅自激振动。通过k-ε模型验证大涡模拟计算结果的准确性。同时,对比环面节流与小孔节流静压气体轴承内气体压力波动的幅值,证明漩涡是导致静压气体轴承产生自激振动的直接原因。计算结果还表明,随着气膜厚度的增加,流场内气体压力波动的幅值先增大后减小,在超精密静压气体轴承设计时,应避免最大压力波动时的气膜厚度接近最大刚度时的气膜厚度,使轴承具有最佳刚度的同时,自激振动得到有效抑制。
In order to fred out the mechanism of the micro self-vibration of aerostatic thrust bearing, large eddy simulation（LES） is used to analyze the flow field of the bearing with pocketed orifice-type restrictor. The results show that there are complicated vortexes near orifice outlet. Gas pressure and velocity change gradually from the centre to the edge of the vortexes. It is the repetition of the generation and crack of vortexes causes gas pressure to fluctuate with gas flow inside the bearing and induces the bearing to be micro self-vibration. By comparing to the calculation results of standard k-e model, the correctness of LES is validated. Moreover, the mechanism of vortexes induce the micro self-vibration of aerostatic thrust bearing is validated by comparing to the flow field of aerostatic thrust bearing with inherently orifice-type restrictor. The results also indicate that there exists a maximum value of the magnitude of pressure fluctuation with the increases of film thickness. Therefore, the film thickness of the maximum pressure fluctuation should not be close to that of the maximum stiffness in order to make the bearings with better stiffness and less self-vibration simultaneously.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2013年第13期56-62,共7页
Journal of Mechanical Engineering
基金
国家自然科学基金(50905171,51275499)
浙江省自然科学基金(Y1080100)资助项目
关键词
静压气体轴承
微幅自激振动
大涡模拟
漩涡
Aerostatic beating Micro self-vibration Large eddy simulation Vortex
