## 3 The Numerical Simulation of the Floating Ring Rotor System
### Analysis of Oil Film Clearance and Oil Film Flow  
The flow rate of the oil hole channel is illustrated in Figure 18 along the squeeze zone of floating rings 1 and 2. The flow rate is defined as \"the mass of fluid passing through the oil hole per unit time\". During the very short transient start-up process of the system, the quasi-periodical behavior of the flow is obvious. One finds that the change in the flow rate is periodic when the system reaches a steady state. The flow rate changes from positive to negative during one period. The time point where the flow rate is positive indicates that the channel is located in the positive pressure zone, and the oil film is squeezed out. The lubricating oil film in the inner cavity is mainly affected by the squeezing effect from the channel to the outer cavity. On the contrary, the channel is in the negative pressure zone when the flow rate is negative. The lubricating oil flows from the outer oil cavity to the inner oil cavity, so as to keep the balance of the lubricating oil flow in the oil cavity. Simultaneously, one finds that within one period, the positive flow rate has a peak with a larger value while the negative flow rate has two valleys with a smaller value. Figure 12 illustrates that in the whole oil film pressure distribution, the area of the positive pressure convergence zone is small and the pressure is large, which includes only one channel, and the negative pressure zone contains two channels. The maximum flow rate of floating ring 2 can reach 2 kg/s. In addition, the maximum flow rate of floating ring 1 is 5 kg/s, which changed significantly and greatly impacts the squeezing performance.  
The relationship between the minimum oil film clearance thickness and time is shown in Figure 19. In the model set, the bearing inner clearance is 0.02 mm, and the bearing outer clearance is 0.08 mm, which is the initial oil film clearance. From the analysis results of the above figure, note that the minimum oil film clearance of the inner film of the floating ring bearing 1 fluctuates very little due to the limitation of the initial gap; the minimum oil film clearance of the outer film undergoes a significant reduction within 0.02 s of the initial transient stage. The clearance thickness drops from 0.08 to 0.03 mm and reaches 0.045 mm within 0.02-0.05 s, and then reaches a steady state. The change rule of the minimum oil film clearance of bearing 2 is similar to that of bearing 1, but the fluctuation range of the minimum oil film clearance of the outer film is relatively small. The initial transient state drops from 0.08 to 0.041 mm and then returns to 0.058 mm, reaching a steady state. The minimum oil film clearance of bearing 2 is greater than that of bearing 1. Within 0.02 s of the initial transient phase, the minimum oil film clearance of the inner oil film decreases significantly, almost approaching zero. Due to the existence of oil holes on the  
Figure 17: The trajectory of the floating ring center.  
floating ring, after squeezing out too much oil, the clearance of the oil film will continue to decrease and the pressure of the oil film will increase. This result may cause the oil film to rupture somewhere in the squeeze zone, and the journal and the floating ring are in direct contact and friction. At the same time, a strong nonlinear disturbance to the rotor system is generated, resulting in increased vibration; and the wear of the floating ring will shorten its longevity.