## 5 Results
Note that the density at the loaded pads' trailing edges becomes smaller than the ambient value (426 kg/m\({}^{3}\)) because of the significant temperature rise in Figure 9c. The viscosity follows the trends of the density with an increase in supply pressure. Figure 10: Centerline (**a**) density and (**b**) viscosity vs. circumferential coordinate for increasing supply pressures. Static load = 100 N, and rotor speed = 60 krmp. Figure 9: Centerline (**a**) film thickness, (**b**) pressure, and (**c**) temperature vs. circumferential coordinate for increasing supply pressures. Static load = 100 N, and rotor speed = 60 krmp. Figure 11 shows the journal eccentricity ratio versus rotor speed for different supply pressures at a static load of 100 N. An increase in the supply pressure dramatically reduces the eccentricity ratio. The decrease in journal eccentricity with a supply pressure of 20 MPa is \(\sim\)65% compared to that for hydrodynamic TPJB at 60 krpm. The journal eccentricity ratio also decreases as the rotor speed increases owing to the increased hydrodynamic effect. However, the effect of the rotor speed on the eccentricity is relatively less significant for hybrid TPJBs, as in Refs. [23; 24]. Figure 12 displays the minimum film thickness versus rotor speed for increasing supply pressures. In general, the minimum film thickness is greater for the hybrid TPJB than for hydrodynamic TPJB owing to the decreased eccentricity ratio, and it further increases with an increase in the supply pressure. The minimum film thickness for the hybrid TPJB with a supply pressure of 20 MPa increases by \(\sim\)80% compared with that for the hydrodynamic case at the lowest rotor speed. The minimum film thickness increases with increasing rotor speed; however, the degree of increment for the hybrid TPJB is lower than that for the hydrodynamic TPJB. The significant increment in the minimum film thickness indicates a considerable improvement in the load capacity due to the external pressurization. Figure 13 shows the variation of the maximum film pressure with increasing rotor speed for different supply pressures. The maximum pressure increases with an increase in the supply pressure and rotor speed. The hydrodynamic TPJB has the lowest maximum pressure. As shown in Figure 14, the predicted bearing drag power loss increases nonlinearly with the rotor speed. The hybrid TPJB has a higher power loss than the hydrodynamic TPJB because of the increase in the viscosity of sCO\({}_{2}\). The change in power loss as the supply pressure increases from 10 to 20 MPa is small. Figure 11: Journal eccentricity ratio vs. rotor speed for increasing supply pressures. Static load = 100 N.  
Figure 12: Minimum film thickness vs. rotor speed for increasing supply pressures. Static load = 100 N.  
Figure 15 shows the direct stiffness coefficient plotted against the rotor speed for the increasing supply pressures. The stiffness coefficient increases with an increase in rotor speed for both hydrodynamic and hybrid lubrication. Most importantly, external pressurization significantly increases the stiffness coefficient. Note that the stiffness increases by ~85% for a supply pressure of 20 MPa compared to that for the hydrodynamic TPJB at the highest rotor speed. As shown in Figure 16, the direct damping coefficient decreases slightly with an increase in rotor speed. The increasing supply pressure increases the damping coefficient, as in Ref. [20]. The hybrid TPJB predicts damping coefficients lower than those of the hydrodynamic TPJB without recesses. Figure 14: Power loss vs. rotor speed for increasing supply pressures. Static load = 100 N.  
Figure 13: Maximum pressure vs. rotor speed for increasing supply pressures. Static load = 100 N.  
Figure 15: Stiffness coefficient vs. rotor speed for increasing supply pressures. Static load = 100 N.