A transient hydrodynamic lubrication comparative analysis for misaligned micro-grooved bearing considering axial reciprocating movement of shaft

A transient hydrodynamic lubrication model is proposed to investigate the lubrication performance of micro grooved journal bearings, considering the axial flow caused by the axial reciprocating movement of the shaft. The lubrication performance of the bearing engineered with three different microgroove distributions, i.e. straight groove, spiral groove, and herringbone groove are compared systematically, including the load capacity and friction coefficient. The results suggest that the herringbone-grooved bearing exhibits the maximum load capacity in the positive axial movement, followed by straight-grooved bearing, and finally spiral-grooved bearing. The spiral-grooved bearing produces the minimum fluctuation amplitude of load capacity and attitude angle in one reciprocating period. The increased frequency of the axial movement can increase the value of load capacity for three micro-grooved bearings during the positive movement of the shaft; however, it does not affect the distribution trends of load capacity among the three micro-grooved bearings. Moreover, the effects of groove angle (beta), degree of misalignment (D-m), and misalignment direction angle (alpha) on the lubrication performance of the micro-grooved bearing are investigated. The results indicate that the herringbone-grooved bearing exhibits better lubrication performance than the spiral-grooved bearing in the positive axial movement at any beta. The present study also indicates that the load capacity of considering axial movement is more sensitive to D-m, than that of not considering axial movement. The misalignment direction angle will result in the decreased load capacity of the micro-grooved bearing.