## 3 Research Results and Discussion
### Simulation and Experimental Results
The bearing capacity of an HTB is the product of the effective bearing area and pressure in the groove. Given the effective bearing areas of the two types of HTBs are constant, in the annular groove, it is higher than that of the crossing groove, and the difference increases with an increase in the water injection pressure. Figure 12: Displacement under dynamic load. Note that the bearing capacity of an HTB decreases rapidly with an increase in the thickness of the water film in the range of 0-0.06 mm of water film thickness. When water film thickness becomes thicker than 0.05-0.06 mm, bearing capacity is relatively small and even. In addition, high water injection pressure can remarkably increase bearing capacity. However, the maximum water injection pressure often is the discharge pressure of WSSCs. This discharge pressure is sufficient to form a thick water film and to support a star wheel. Furthermore, the working loads of a star wheel in WSSCs have the parameters listed in Table 1 and labeled in Figure 13. Under the working loads, sufficient thick water film can be formed. By contrast, the relations between loads and lubricating films of the simulation and experimental results have the same changing trend. However, the simulated and experimental data points have some slight differences for the same axial force and same injecting pressure. The error may come from some deflections arising from the rotating shaft and bearing ring in the rig. In the numerical simulation, the static and rotating rings of the bearing are supposed to be parallel to each other. Moreover, errors may come from the standard testing of the water film measurement in the rig. Comparison is drawn in Figure 14a on the variation of the water supply with the water film thickness of two types of HTBs. Figure 14b shows the relationship between water supply and water film thickness of HTBs under three different water injection pressures. The experimental and simulated results are likewise listed. Figure 14 shows that the water supply of an HTB with the crossing groove is smaller than that of the annular groove. Circumferential and radial flows are present owing to the existence of radial short channels, as shown in Figure 8. The existence of a radial short channel also increases the flow channel of the lubricant water, thereby reducing the amount of water. The water supply difference between the two types of HTBs is extremely small when the water film thickness is small. The difference gradually increases with an increase in water film thickness, which is due to the cubic correlation between water supply and bearing clearance according to the empirical formula. Figure 13: Comparison of the bearing capacity for (**a**) annular groove vs. crossing groove (simulated results), (**b**) crossing groove (simulated results vs. experimental results). Compared with the simulation results, the experimental and simulation values describe the same trend of water flowrate change in the sliding clearance of an HTB. The water flowrate measured by the experiment is larger than that of the simulation. The possible reason for errors is that the numerical calculation model is based on the ideal assumption that water film thickness is uniform. The experimental test focuses on engineering practice, which may be caused by a machining error, assembly error of bearing working surface, or tilt between working faces of HTB, resulting in uneven actual water film thickness. Thereafter, water supply increases.