应用有限体积法研究空气静压导轨力学特性

Study on mechanical characteristics of aerostatic bearing with finite volume method

研究了润滑气膜的主要力学参数。引入有限体积法,应用理想气体等温条件下的k-ε模型封闭控制方程组对润滑气膜的力学特性进行数值分析,得出不同气膜厚度下导轨工作面上的压强分布规律。数值结果表明:导轨内气膜从节流孔沿工作面到导轨边缘的压强分布规律并非按雷诺润滑方程均匀递减变化,而是在节流孔附近存在半径约为500μm的负压区;在静压导轨气膜厚度与承载力分析的基础上,指出气膜与导轨间的气固耦合所引发的导轨弹性自激振动是静压导轨实现纳米级定位的主要制约因素。本项研究为导轨自激振动抑制、气膜振幅减小乃至空气静压导轨整体精度提高等工作做了有益探索。

The research work on mechanical characteristics of aerostatic bearing was introduced. By introducing finite volume method of Computational Fluid Dynamics （CFD）, the mechanical characteristics of a air film were analyzed numerically using the control closed equation set k-ε model at the condition of isothermal air and the pressure distributing law of air film with different thicknesses on aerostatic bearing working plane was obtained. The numerical analysis shows that the pressure distributing law of the air film from orifice to edge of air-bearing along the working plane is not degression followed by simplified Reynolds equation, but fluctuation in that the air flow pressure sharply drops under the atmospheric pressure nearby orifices, then gradually increases above the atmospheric pressure and reverses finally. Based on the analysis of air film thickness and aerostatic -bearing capacity, this paper points out that elastic self-excited vibration caused by the gas-solid coupling between air film and aerostatic bearing is the main restriction of aerostatic bearing in nano-positioning. The conclusions will be significant in eliminating the self-excited vibration, decreasing air film amplitude and improving the accuracy of aerostatic bearing in research on the mechanical characteristics of aerostatic bearing.