## 3 Results and Discussion
### Comparisons of FSH Coupling Performance  
In this section, the FSH coupling performances of the JWR system, including the contact load, maximum temperature, and maximum thermal-elastic deformation, obtained with the aligned shaft case and the misaligned shaft case under different external forces are studied comparatively. In order to make the sensitive studies clearer for readers, under various parameters, a dimensionless process for pressure (hydrodynamic and contact) and deformation (elastic and thermal) is performed in the figures of the current section. The dimensionless process of pressure and load can be expressed as:  
\[\overline{p}=\frac{p}{\eta N}\bigg{(}\frac{C}{R_{1}}\bigg{)}^{2},\overline{F} =\frac{F}{\eta N}\bigg{(}\frac{C}{R}\bigg{)}^{2} \tag{30}\]  
where \(N\) is the revolutions of the journal per second. The dimensionless process of deformation can be expressed as:  
\[\overline{\delta}=\frac{\delta}{\sigma} \tag{31}\]  
The comparisons of the contact load and the friction coefficient between the two cases are shown in Figure 13a. The contact load yielded by the misaligned shaft case was almost same as that from the aligned shaft case when the external load was less than 3 kN. However, when the external load increases from 3 to 8 kN, the contact load generated by the misaligned shaft case becomes higher than that of the aligned shaft case; the reason for this is that the deflected shaft effect is gradually enhanced with the increasing external load. Additionally, it can be found from Figure 13a that the friction coefficient for both cases decreased when the load capacity increased from 1 to 3 kN, which conforms to the elastohydrodynamic lubrication theory [4]. Figure 13b,c show comparisons of the maximum temperature and thermal-elastic deformation, respectively. The maximum temperatures of the misaligned shaft case and the aligned shaft case were almost the same when the external load was less than 4 kN, implying that the deflection of the propeller shaft almost does not affect the thermal performance of the WLRSB under a relatively light load condition. Meanwhile, the maximum water film temperature of the misaligned shaft case became higher than that of aligned shaft case when the load capacity was larger than 4 kN. Furthermore, Figure 14a,b can be used to explain the relationship of the maximum water film temperature between the two shaft cases. As shown in Figure 14b, for the misaligned shaft case, the contact pressure occurred mainly in the outlet water side, and its value increased sharply with the increase  
Figure 12: Comparisons of temperature distribution of the water film obtained with a misaligned shaft case and an aligned shaft case under different axial sections of the WLRSB: (**a**) at z/L = 0.5; (**b**) at maximum temperature; (**c**) at z/L = 1.  
in load capacity. It can also be found from Figure 14b that for the load capacity in the range from 4 to 10 kN, the load capacity yielded by the misaligned shaft case was obviously larger than that yielded by the aligned shaft case (see Figure 14a). The results indicate that the misaligned shaft generates more friction heat, \(\Phi_{\rm C}\), compared with the aligned shaft. However, the misaligned shaft provides a smaller average temperature of journal than that of aligned shaft case when the load capacity is larger than 4 kN. This may be due to the fact that the aligned shaft yields a larger contact area under heavy load conditions. As expected, the misaligned shaft gives a larger elastic-thermal deformation than the aligned shaft, as shown in Figure 13c. Figure 13: Comparisons of the FSH performance of the JWR system obtained with two cases of shaft, i.e., aligned shaft case and misaligned shaft case: (**a**) contact load and friction coefficient; (**b**) average temperature of journal and maximum temperature of water; (**c**) elastic and thermal deformation.