# Multiphase Conjugate Heat Transfer Analyses on the Assembly Situation of Rotary Shaft Seals
## 4 Discussion
### Variants with Additional Elements
In the simulation, it was, therefore, assumed that the domain _oil chamber bearing_ would be completely filled with oil. In the experiments, it was observed that this volume did indeed fill completely with oil. However, the bearing continued to pump oil even when the volume was already completely filled with oil, which could have resulted in a higher pressure on the sealing edge. The sealing edge may, therefore, have been pressed against the shaft on the oil side, which could have led to higher friction. Compared to the reference variant, the sealing edge would, thus, be pressed differently on the shaft surface for the O-arrangement of the tapered roller bearings due to the overpressure on the oil side. The parameters defined in the simulation model for determining the frictional heat in the sealing contact were based on the reference variant and were, therefore, incorrect for the O-arrangement of the tapered roller bearings. For all other simulated variants with bearings, the assumed parameters seem to be correct, as the measured values agreed well with the results from the simulations. The rotating shaft distributed the oil in the oil chamber, but due to gravity, especially at low rotational shaft speeds, there was still more oil in the lower half of the oil chamber, as shown in Figure 11. Since oil conducts heat better than air, as shown in Table 1, the heat generated in the sealing contact was dissipated better in the lower area of the oil chamber. To analyze these fluctuations in a circumferential direction, a line was placed in the sealing contact around the circumference of the shaft sleeve, as shown in Figure 19a. On this line, the temperature was evaluated in steps of \(\Theta\) = 1\({}^{\circ}\) for each variant with bearings and the rotational shaft speed \(n\) = 2000 rev/min, as shown in Figure 19b. The two vertical dashed lines mark the two positions \"top\" and \"bottom\". The position \"top\" refers to the location on the circumferential line with the most-positive y-coordinate. The position \"bottom\" analogously refers to the location on the line with the smallest y-coordinate. Due to the better thermal conductivity of the oil, the temperatures in the lower part and especially at the \"bottom\" position were generally slightly lower than the temperatures at the \"top\" position. For example, for the X-arrangement, the temperature varied between approx. 114.7 \({}^{\circ}\)C and 116.8 \({}^{\circ}\)C, as shown in Table 6. This temperature difference is negligible. \begin{table}
\begin{tabular}{c c c c c} \hline  & **Be\_X** & **Be\_O** & **Be\_Ba** & **Be\_Cyl** \\ \hline \(\theta_{\min}\) along the & & & & \\ circumferential line [\({}^{\circ}\)C] & 114.7 & 95.3 & 94.3 & 93.8 \\ \(\theta_{\max}\) along the & & & & \\ circumferential line [\({}^{\circ}\)C] & 116.8 & 97.5 & 97.7 & 97.1 \\ \end{tabular}
\end{table} 
Table 6: Minimum and maximum temperatures along the circumferential line in the sealing contact, \(n\) = 2000 rev/min. A second horizontal line 49 mm long and 0.7 mm below the sealing contact, was defined, shown in Figure 19(a). At 200 equidistant data points across the line, the temperature was evaluated for the four variants with bearings, as shown in Figure 19(b). The temperature plot over the x-coordinates of the horizontal line looks like a slightly asymmetrical Gaussian distribution curve, with the maximum at the position of the sealing contact.