# Multiphase Conjugate Heat Transfer Analyses on the Assembly Situation of Rotary Shaft Seals
## 4 Discussion
### Variants with Additional Elements  
In Figure 17, the temperatures obtained from the simulation of the variants with the slinger disc and baffle plate are compared with the measurements. The simulation results are displayed in full color, and the temperatures obtained from the measurements are displayed hatched. The two variants with baffle plate deviated strongly from the measurement results. The temperature difference between the measurement results and the simulation results for the variant BP_large was almost 50 K for the shaft speed \(n=8000\) rev/min. For the variants with the slinger disc, the temperature difference was generally much smaller, the maximum difference being about 10 K. A reason for the large temperature difference between the measurement and simulation for the variants with the baffle plate could be that the baffle plate was cut at the inner diameter for the experiments in order to attach a temperature sensor. This cut may have caused the oil to be better mixed near the sealing ring. The oil heated up through the frictional heat near the sealing contact, thus, mixed more quickly with the cooler oil further away from the sealing contact. Thus, the oil cooled down faster in the area near the sealing contact due to its better mixing with the cooler oil,  
Figure 16: Temperature measurement procedure: (**a**) sealing ring with interfaces; (**b**) location of performed measurements. \begin{table}
\begin{tabular}{c c c c c} \hline \multicolumn{2}{c}{**Input Parameter**} & \multicolumn{2}{c}{**Simulation Results**} & \multicolumn{2}{c}{**Measurement**} \\ \hline
**Shaft Speed \(n\)** & **Circumferential Speed \(v_{U}\)** & \(\theta_{\text{Max}}\) [\({}^{\circ}\)Cl at** & \(\theta_{\text{Max}}\) [\({}^{\circ}\)Cl at** & \(\theta_{\text{Max}}\) [\({}^{\circ}\)Cl at** \\
**[rev/min]** & **[m/s]** & **RSS-Shaft** & **RSS-Environment** & **RSS-Environment** \\ \hline
2000 & 8.38 & 98.1 & 95.9 & 95.3 \\
4000 & 16.76 & 109.4 & 105.4 & 105.6 \\
8000 & 33.51 & 145.2 & 138.9 & 124.8 \\ \hline \end{tabular}
\end{table} 
Table 5: Simulation results and measurements of the reference variant, depending on the input parameter \(n\). which is why the measured temperatures were much lower than the temperatures obtained from the simulations. Figure 18 compares the temperature values obtained from the simulations with the measured temperatures for the different bearing arrangements. The rotational shaft speeds tested with the tapered roller bearings on the test bench were \(n_{1}=1000\) rev/min, \(n_{2}=2000\) rev/min and \(n_{3}=3200\) rev/min. The ball bearings and cylindrical roller bearings were tested with \(n_{1}=2000\) rev/min, \(n_{2}=4000\) rev/min and \(n_{3}=6300\) rev/min. The same shaft speeds were used for the simulations. Figure 17: Variants with slinger disc or baffle plate: simulation results (full colored) compared to the measured temperatures (hatched). Figure 18: Variants with bearings: simulation results (full colored) compared to the measured temperatures (hatched). The largest temperature difference of approx. 26 K for \(n_{3}\)= 3200 rev/min and approx. 15 K for \(n_{2}\) = 2000 rev/min occurred for the tapered roller bearings in the O-arrangement. This difference may have been due to the fact that the frictional heat generated in the sealing contact was incorrectly assumed in the simulations: the frictional torque of the sealing ring was measured several times in the experiments with the reference variant, i.e., without additional elements and with a solid shaft. In these experiments, the oil chamber was filled with oil up to the center of the shaft. Based on these measured frictional torque values, the parameters in Equation (18) were determined. These parameters were identical for all the simulated variants. This means the frictional heat generated in the contact area between the sealing ring and the shaft was assumed to be the same for all the variants. Due to the pumping effect of the bearings, the fluid was pumped towards the sealing ring for the O-arrangement of the tapered roller bearings.