Effect of Internal Structure of Circular Dimples on Hydrodynamic Lubrication Characteristics of Thrust Bearings

In this study, the effects of three types of dimples with different internal structures on the fluid lubrication characteristics of seal-like thrust bearings were experimentally and numerically investigated. In the experiments, the load-carrying capacity and the frictional torque were measured. The measurements were performed with a fixed constant film thickness. The behaviors of cavitation bubbles occurred within the dimples were observed through the rotating glass plate. Three types of internal structures of dimples were tested: cylindrical, spherical and conical. The measurement results were simulated by using the Reynolds equation. In addition, applying the periodic condition, a single dimple was analyzed. As the results, in three types of dimples, the load-carrying capacity increased as the rotational speed increased. The cylindrical internal structure built up the largest pressure at the trailing edge of dimples, and consequently the largest load-carrying capacity. The frictional torque also increased with increasing the rotational speed in the dimpled bearings. However, the effect of the internal structure on the frictional torque was not significant. Analytical results showed that the pressure reached the maximum value at the trailing edge of the cylindrical internal structure. The conical and sphere internal structure had the maximum value slightly inside the trailing edge.