气体静压径向轴承气膜流场及承载特性分析

Analysis of Gas Film Flow Field and Load Capacity of Aerostatic Journal Bearing

研究偏心率及不同供气压强条件下,气体静压径向轴承节流孔附近的气膜流场特性及承载力变化情况,并通过优化节流孔张角,提高轴承承载力。建立气体静压径向轴承三维模型,划分网格并确立模型的边界条件,采用Fluent软件对轴承内部气膜流场进行仿真计算。计算结果表明,气体静压径向轴承偏心率的增加,会导致区域气膜的压力差增大,从而提高轴承的承载力。轴承承载力同样会随着供气压强的增大而增大,但增幅会随着供气压强的增大而逐渐变小。但当供气压强增加到临界值时,由于节流孔附近激波的出现,将导致承载力随着供气压强的进一步增大而降低。通过改变轴承节流孔张角,可消除轴承气膜内的涡流现象,并改善气膜流场特性,降低能量损失,提高轴承承载力。经过分析对比,发现最优节流孔张角介于50°到60°之间。

The influences of eccentricity and supply pressure on the gas film flow field and load capacity of aerostatic journal bearing are studied in this paper.And the load capacity of the bearing can be improved by optimizing the orifice cone angle.A three-dimensional model of aerostatic journal bearing system is established.The grid is divided and the boundary condition of the model is determined.Fluent Software is adopted to simulate the internal flow field of bearing.The calculation results show that the eccentricity of the bearing improves the load capacity by increasing the pressure difference inside the gas film.The load capacity also increases with the increasing supply pressure,but the increasing range gradually decreases with the increase of pressure.As the supply pressure improves to a critical value,the load capacity may decrease due to the occurrence of shock waves near the orifice.Further studies reveal that the eddy current in bearing film can be eliminated by optimizing the orifice cone angle.The flow field characteristics of the gas film can be therefore improved,the energy loss is reduced,and the load capacity of the bearing is improved also.The optimal orifice cone angle is found between 50 and 60 degrees.