基于分子碰撞理论的静压导轨气膜内部微振动现象的分析

静压导轨气膜微振动已经成为制约气浮支撑发展的重大问题。为证实气膜内部的微振动本质是高压气体在流动过程中与支撑底面、节流器壁面和气浮块壁面发生碰撞,导致气膜区域内表面受到变化的冲量,形成不规律的水平和垂直方向冲击力,使得气浮块发生基于系统固有频率及其倍频的微振动。通过理论分析,建立描述气膜支撑区动力学特性的振动模型,并进行了仿真分析和实验对比验证,证实了气膜内部微振动的形成机制。分析结果表明:有气腔与无气腔的节流方式都会产生气膜微振动;进气孔直径相同情况下,有气腔节流方式下的振动大于无气腔节流方式下的振动;振动峰值的频率点基本一致,其频域曲线所显示的振动规律也基本相同。

Analysis of Micro Vibration in Gas Film of Aerostatic Guide Way Based on Molecular Collision Theory

Micro vibration of the aerostatic guide way has a significant impact on its dynamic characteristics and stability , which limits the development of pneumatic component .High pressure gas molecules collide with the supporting surface and the internal surface of the throttle during the flow process .Variable impulse of the surfaces aside for the gas film are affected by the changes of impulse which formed irregular impact force in horizontal and vertical direction .Micro-vibration takes place based on the natural frequency of the system and its frequency doubling .The vibration model was established to describe the dynamic characteristics of the gas film .By comparing computational results and experimental data , formation mechanism of the micro vibration in the gas film was confirmed .The result shows that the micro vibration of gas film can be produced no matter whether there is a gas chamber or not in the throttle .Mean-while, The micro vibration of the guide way with air chamber is greater than that without any chamber under the same conditions .The frequency points of the vibration peaks are almost the same , as well as the vibration pattern in the frequency domain .