Analysis Of The Dynamic Performance And The Stability Of Liquid-lubricated Herringbone Grooved Journal Bearing (HGJB) With Micro-polar Lubricants

This work employs operator-splitting method (OSM) / finite element method (FEM) to study dynamic performance and the stability of liquid-lubricated herringbone grooved journal bearing (HGJB) with micro-polar lubricants. Load capacity, friction resistance, stiffness/damping coefficients and critical rotor mass were investigated. In liquid-lubricated film of a hydrodynamic bearing, cavities may occur in negative-pressure region. The film cavity plays a significant role to the film stability of a bearing. The boundary conditions of the cavity region are extremely important to bearing load capacity and film stability. In this paper, the JFO condition, satisfied with global mass continuity, is incorporated into an universal Reynolds equation with micro-polar fluid which is solved for the oil film pressure using OSM and FEM. The bearing load capacity and friction resistance were given, and stiffness/damping coefficients and critical rotor mass were obtained by solving a pressure perturbation equation with micro-polar lubricants.Visco-elasticity of micro-polar fluid is characterized by two parameters of coupling number and molecular characteristic length. Numerical results indicate that under small eccentricity the film stability and load capacity of HGJB with micro-polar fluid lubricants are generally better than those with Newtonian fluid lubricants. At the same time, the bearing friction resistance is increased slightly. Under the high coupling number, the smaller the ratio of film thickness to molecular characteristic length, the higher the load capacity and the better the stability of the HGJB. This paper also shows that load capacity and the film stability of HGJB can be improved by optimizing parameters of micro-polar lubricants.