Abstract: Surface textures of fan-shaped grooves of axisymmetrical distribution are designed on one of the parallel thrust bearing surfaces to improve the hydrodynamic lubrication performance of the bearing. In order to optimize the groove parameters (including the groove number, depth and area ratio), a regressive formula of the bearing load carrying capacity is obtained, based on the calculation results of the load carrying capacity by solving Reynolds equation under various combinations of bearing inner and outer diameters, rotation speed, lubricant viscosity, bearing clearance as well as the groove parameters. A formula of the bearing friction coefficient is derived using the regressive formula of the load carrying capacity. Based on these formulae, the optimal groove parameters are found under the four different kinds of constraints and optimization goals: Given the bearing clearance, requiring the maximal load carrying capacity or minimal friction coefficient; given the load carrying capacity, requiring the maximal bearing clearance or minimal friction coefficient. Furthermore, the validity of the optimal design is confirmed by comparing the load carrying capacity, bearing clearance and friction coefficient calculated by the regressive formulae with the full simulation results of Reynolds equation. Friction experiments are carried out on three surface textures of fan-shaped grooves with different groove numbers and depths. It is found that the trend of the calculated friction coefficient is the same as that of the experimental one, and the optimal results of the groove parameters are credible.

Key words: Cavitation boundary condition, Optimal design, Parallel thrust bearing, Reynolds equation, Surface texture