低含气率影响下圆柱动静压轴承特性分析

为研究低含气率条件下,温度和气泡含量对润滑油黏度的影响,采用涡轮油和氮气制备油气两相流,在不同温度下采集含气率和动力黏度,拟合得到两相流的黏度计算模型。针对带有深浅腔的圆柱动静压轴承,基于拟合的黏度模型,结合有限元法和有限差分法联立求解油膜Reynolds方程、能量方程及两相流等效密度模型,分析了不同偏心率下承载力、摩擦力、端泄流量、刚度、阻尼系数和失稳转速随含气率变化的规律。结果表明:含气率在2.50%以内,含气率越高,黏度值越大;不同偏心率下油膜承载力、摩擦力和动力特性参数均随含气率的增加而增加,端泄流量随含气率的增加而减小;计入两相流的影响使稳定性有所提高,失稳转速最高增幅为9.14%。

Characteristic analysis of cylindrical hydrodynamic/hydrostatic bearing under low gas fraction

To study the variation of lubricant viscosity with temperature and bubble content under the low gas fraction, the turbine oil and nitrogen were used to prepare two-phase flow. The gas fraction and dynamic viscosity were measured at different temperatures to fit the viscosity model of the two-phase flow. Based on the fitting viscosity model, the Reynolds equation, energy equation, and the equivalent density model of the two-phase flow lubricant were proposed and solved for a cylindrical hydrodynamic/hydrostatic bearing with the combination of the finite element method and finite difference method, meanwhile the variation of load carrying capacity, friction force, oil leakage, stiffness, damping coefficients and threshold speed with gas fraction was examined. The results showed that the viscosity improved with the growth of gas fraction within the 2.50% of gas fraction; as the gas friction grew, load carrying capacity, friction force, and dynamic coefficients increased while the oil leakage declined; the stability performance was promoted and the threshold speed increased by 9.14% at most considering the effect of two-phase flow lubricant.