## 4 Analysis of the Results
Figures 21-25 show the obtained temperature distributions on the top foil, as well as the vibration trajectory at a given rotational speed. The vibration trajectories of the second journal are shown and described in more detail in Figures 11-16. This foil was modelled as a perfectly cylindrical surface and its lock was at the top (at the location 0 mm). The position of the journal is not taken into account in the figures because it would be difficult to visualize, but in their descriptions it is indicated in the order X and Y, counting from the bearing axis. The two-dimensional trajectory is in the plane of symmetry of the bearing (red colour) and its scale is on the back plane. In Figure 21a,b, similar temperature values were observed but slightly different temperature distributions, probably due to the different positions of the journal in the bearing. Along with a different static equilibrium point, at a given rotational speed, the size of the trajectory also decreased, which translated into slight differences (Figure 22a,b). In each case, in the lower part of the foil, in the middle of its width, an area of higher temperature can be seen, while in the middle, near the penultimate column of thermocouples, there is an area of low temperature (near the free end). In the upper part of the top foil, on the lock side, an area of increased temperature is observed, with much lower values at the edges, which may be related to the suction of air from the environment. At these four analyzed speeds, the distribution appears to be symmetrical, which is related to the nature of the operation of the entire rotor. At lower speeds (Figure 23a,b), the vibration trajectories enlarged slightly and the journals reached the static equilibrium position farther from the bearing axis than at 23,983 rpm. The temperature values remained at a similar level but the nature of the temperature distribution changed. The area of lower temperature, located closer to the  
Figure 20: Temperature distribution on the flat surface of the top foil at: (**a**) maximum speed; (**b**) minimum speed. free end of the foil, remained unchanged but in the lower part of the foil, the temperature distribution lost its symmetry. This effect is due to several factors: the shape of the ellipse, and the direction of the major axis directed to the location of the higher temperature area; the position of the journal in the bearing; the emerging eccentricity of the journals of the bearings; and the developing conical vibration mode of the rotor. Figure 23: Temperature distribution on the surface of the top foil and the vibration trajectory of the journal: (**a**) at the speed of 15,993 rpm (\(-2\) μm, \(-8\) μm), (**b**) at the speed of 13,988 rpm (\(-2\) μm, \(-8\) μm). Figure 21: Temperature distribution on the surface of the top foil and the vibration trajectory of the journal: (**a**) at the speed of 23,983 rpm (\(-2\) μm, \(-1\) μm), (**b**) at the speed of 21,980 rpm (\(-3\) μm, \(-4\) μm). Figure 22: Temperature distribution on the surface of the top foil and the vibration trajectory of the journal: (**a**) at the speed of 19,991 rpm (\(-3\) μm, \(-5\) μm), (**b**) at the speed of 17,990 rpm (\(-3\) μm, \(-7\) μm). In Figure 6, it can be seen that at speeds of 15,993 rpm and 13,988 rpm, the difference in the positions of both journals is 13 \(\upmu\)m while in Figure 12, it can be observed that the vibration mode of the rotor took a conical form. As the rotational speed decreased to 11,978 rpm (Figure 24a), the elliptical trajectory of the journal vibrations increased and its major axis rotated nearly perpendicular to the lock of the top foil. The journal slightly changed its position and there was still a 13 \(\upmu\)m eccentricity with a conical vibration mode of the rotor. In the upper part of the foil, at its visible edges as well as at the free end, the low-temperature area increased. The maximum temperature reached almost 50 \({}^{\circ}\)C, which means an increase of about 5 \({}^{\circ}\)C compared to the higher speeds.