带浅腔的空气静压轴承节流孔出口处流场计算与分析

Calculation and Analysis of Flow Field at the Outlet of Orifice ofAerostatic Bearing with Shallow Cavity

为了进一步揭示具有浅腔的空气静压轴承节流孔出口处气膜流场的影响因素和规律,建立空气静压轴承节流孔出口处的物理模型,采用Laminar、k-ω以及k-ε3种模型对空气静压轴承节流孔出口处气膜流场区域的NS方程进行数值计算,分析气膜间隙和供气压力对节流孔出口处气膜流场的影响。结果表明:空气静压轴承在节流孔出口处存在压力陡降现象,在气膜浅腔与气膜间隙交界处的陡降更为明显,这对精密运动机构和精密测量设备的精度和稳定产生一定影响;3种计算模型的计算结果有较好的一致性,Laminal模型和k-ω模型数值计算结果更为接近;随着空气静压轴承气膜间隙和供气压力的增大,其节流孔出口处的压力陡降和马赫数剧升幅度也随之增大。

In order to further explore the influencing factors and laws of the film flow field at the outlet of the orifice of aerostatic bearing with shallow cavity,the physical model of the outlet of the orifice of the aerostatic bearing was established,and the NS equation of the film flow field area at the outlet of the orifice of aerostatic bearing was solved by using three models,i.e.Laminar model,k-ωmodel and k-εmodel.The effect of air film clearance and supply pressure on the film flow field at the outlet of the orifice of aerostatic bearing was analyzed.The results show that there was a sharp pressure depressing at the outlet of the orifice of the aerostatic bearing,especially at the interface between the shallow cavity and the clearance of the air film,which has a certain impact on the precision and stability of precision motion mechanism and precision measuring equipment.The calculation results of the three models are consistent,and the numerical results of the Laminal model and the k-ωmodel are closer.With the increase of air film clearance and supply pressure,the sharp depressing amplitude of the pressure and the sharp rise amplitude of the Mach number at the outlet of the orifice of aerostatic bearing are increased.