# Identification and Optimization Study of Cavitation in High Power Torque Converter
## 4 Optimized Design of Cavitation in High Power Torque Converter
### Simulation Analysis of Torque Converter Stator Optimization Scheme  
The optimized stator is discretized into a hexahedral mesh and set up for simulation according to Table 2, and the pump input speed is 1700 r/min for zero-speed stall simulation. The relationships between the \(\Delta\beta_{Dif}\) and \(TR\), \(P_{lowest\_D}\), \(M_{bg0}\) and \(M_{T}\) are plotted as shown in Figure 11.  
From Figure 11, it can be seen that the \(TR\), \(M_{bg0}\) and \(M_{T}\) all have quadratic functional relationships with \(\Delta\beta_{Dif}\), and the \(P_{lowest\_D}\) and \(\Delta\beta_{Dif}\) have approximately primary functional relationships. The specific relation equation is as follows. \[P_{lowest}=-0.0266\cdot\Delta\beta_{Dif}-2.5062 \tag{11}\]  
\[K=-0.0008\cdot\Delta\beta_{Dif}^{2}+0.0444\cdot\Delta\beta_{Dif}+1.4633 \tag{12}\]  
\[M_{bg}=0.8111\cdot\Delta\beta_{Dif}^{2}-46.573\cdot\Delta\beta_{Dif}+1663.3 \tag{13}\]  
\[M_{T}=2.1\cdot\Delta\beta_{Dif}^{2}-128.85\cdot\Delta\beta_{Dif}+7907.4 \tag{14}\]  
Figure 11a shows that the \(TR\) of the hydraulic torque converter tends to increase and then decrease with an increase in \(\Delta\beta_{Dif}\). The difference rate between the maximum and minimum values of the \(TR\) is 6.8%, which is relatively low. It is important to note that this analysis is based solely on objective data and does not include any subjective evaluations. The minimum pressure on the surface of the stator blades tends to increase with an increased \(\Delta\beta_{Dif}\). The difference rate between the maximum and minimum values  
Figure 10: Two-dimensional profiles of blades for different scenarios. \begin{table}
\begin{tabular}{c c c c c} \hline
**Item** & \multicolumn{4}{c}{**Parameter**} \\ \hline Angle of incidence & original & 34.66 & scenarios 3 & 19.66 \\ \cline{2-5} deviation of flow injection & scenarios 1 & 25.16 & scenarios 4 & 17.16 \\ \cline{2-5} \(\Delta\beta_{Dif}\) (\({}^{\circ}\)) & scenarios 2 & 21.16 & scenarios 5 & 14.16 \\ \hline Outlet angle \(\alpha_{outD}\) (\({}^{\circ}\)) & \multicolumn{4}{c}{50.56} \\ \hline inner ring offset (rad) & \multicolumn{4}{c}{0.097} \\ \hline chord length \(L_{D}\) (mm) & \multicolumn{4}{c}{77.82} \\ \hline \end{tabular}
\end{table} 
Table 5: Design parameters for different scenarios. of the minimum pressure is 20.4%. The \(M_{bg0}\) exhibits a downward and then upward trend as the \(\Delta\beta_{Dif}\) increases. The difference rate between the maximum and minimum values of \(M_{bg0}\) is 15.3%. The change in \(\Delta\beta_{Dif}\) is more significant for the \(P_{lowest\_D}\) of the hydrodynamic torque converter and \(M_{bg0}\), which are the most important factors in the optimization. \(M_{bg0}\) has a large effect, while the effect on \(TR\) is small. The analysis of the results of the comprehensive optimization scheme reveals that the \(P_{lowest\_D}\) in the zero-speed condition of Scheme 2 is improved from \(-\)2.78 MPa to \(-\)2.29 MPa, which is 17.6%, while the \(TR\) is improved from 2.017 to 2.040, with a change rate of 1.14%, the \(M_{bg0}\) is reduced from 1020.8 N\(\cdot\)m to 1008.1 N\(\cdot\)m, with a change rate of 1.24%, and Scheme 2 significantly optimizes the \(P_{lowest\_D}\) on the surface of the stator while basically keeping the basic performance unchanged, which can be taken as the preferred scheme. Figure 12 presents a comparison between the simulation results of the original scheme and Scheme 2. As shown in Figure 12a,b, the optimized liquid flow velocity through the stator decreases at the highest velocity in the region where the velocity rapidly increases and sweeps over the nose of the stator, with a decrease rate of 13.5%. Additionally, the low-speed flow region above the front suction surface at the peak position of the stator bending disappears, and the majority of the low-speed region is now close to the surface of the blade. The vortex above the front suction surface at the peak stator bending position is weakened or disappears.