多孔质气悬浮气膜压力特性建模及试验研究

Theoretical and experimental study on pressure characteristics of air film for levitation using porous media

为了研究多孔质气悬浮气膜压力特性以便对玻璃基板的非接触式搬运系统进行性能分析和优化设计,以具有代表性的区域单元为对象,建立包含多孔质特性和间隙流特性的气膜压力动态模型,利用有限体积法(FVM)进行求解.当多孔质表面空气薄膜受到工件的往复振动挤压时,压力响应相对间隙距离呈现明显的滞环现象,表现出弹性特性和阻尼特性.仿真和试验的结果表明,基于动态模型的计算结果与实验值吻合较好.气膜压力刚度系数随着间隙距离的减小而迅速增大,并受到供给流量与区域半径的影响.气膜压力阻尼系数受供给流量的影响甚小,受区域半径的影响显著,表明适当增加导轨宽度可以有效地加快工件自由振荡衰减速度.

A pressure dynamic model including the characteristics of porous media and gap flow was established within a representative region in order to analyze the air film pressure characteristics of pneumatic levitation using porous media,as for performance analysis and optimal design of non-contact conveying system.The model was solved by using finite volume method（FVM）.Results showed that there exists an obvious pressure hysteresis versus gap thickness when a work piece was vibrated back and forth to squeeze the air film,revealing that the pressure response was identified as a representation of spring-damping characteristic.Theoretical and experimental results showed that the dynamic model based calculated results accorded well with the experimental data.Pressure stiffness coefficient of the air film increased greatly as a gap thickness decreased,and varied with the supply flow rate as well as the region radius.Pressure damping coefficient little changed with the supply flow rate,but apparently affected by the region radius,indicating that the decay of free vibration of the work piece can be accelerated by appropriately increasing the width of the conveyor.