# Identification and Optimization Study of Cavitation in High Power Torque Converter
###### Abstract  
Aiming at the phenomenon that a high-power torque converter is susceptible to cavitation, which leads to performance degradation, first, a transient flow field model of the torque converter is established, and CFD simulation and experimental research on the torque converter are carried out to find out the speed ratio region where cavitation occurs in the torque converter as well as the rule of occurrence of cavitation, and then the cavitation identification method based on the difference between the inlet and outlet flow of the torque converter is proposed. Then, the transient flow process inside the torque converter is analyzed, and it is pointed out that the angle between the inlet angle of the stator and the outlet angle of the turbine of the torque converter, i.e., the fluid inflow injection deviation angle is an important factor affecting the cavitation phenomenon. By adjusting the key parameters of the stator blade bone line, the fluid inflow deviation angle of the torque converter stator is optimized, so that the speed ratio range of cavitation under large load conditions is greatly reduced from the original 0-0.5 (50%) to 0-0.15 (15%). Meanwhile, in terms of test performance, the nominal torque of the torque converter is greatly improved under the premise of ensuring that the performance is basically unchanged, in which the nominal torque of the test zero speed is increased by 28.7%, and the cavitation of the torque converter has been greatly improved. torque converter; cavitation; stator; blade angle; CFD +
Footnote †: journal: Medical  
techniques not only contribute to the understanding of cavitation phenomena but also advance the broader field of fluid dynamics and engineering design methodologies. Understanding cavitation behavior allows engineers to optimize torque converter performance under various operating conditions. By controlling cavitation, engineers can tailor torque converter characteristics to meet specific performance requirements, such as maximizing torque multiplication or minimizing energy losses. Meanwhile, by identifying the conditions that lead to cavitation and optimizing the design to mitigate its effects, engineers can improve torque converter durability and life. This, in turn, reduces maintenance costs and increases reliability. In the study of cavitation, [PERSON] discovered through CFD simulation and tests that flow recirculation occurred in the turbine and stator blade passages at low speed ratios. This is a key factor that leads to the occurrence of cavitation [5]. [PERSON] and his team calculated cavitation at various operating conditions using a commercial flow solver with the homogeneous cavitation model and compared the torque converter performance with experimental data. The article indicates that cavitation causes a significant drop in performance [6]. [PERSON] et al. measured the flow pressure in the stator of a torque converter and simulated the transient cavitation flow using computational fluid dynamics. They found that the shedding of cavitation significantly reduced hydraulic performance, hindered fluid flow, and disrupted the stability of the flow field [7]. [PERSON] et al. from Kyushu University in Japan conducted a numerical simulation using the simplified Rayleigh-Plesset cavitation model. They discovered that cavitation begins to occur at the stator when the ambient pressure decreases at lower speed ratios (\(<\)0.4) [8]. [PERSON], from Taiyuan University of Science and Technology in China, conducted a study on the torque converter of the SD bulldozer. The study utilized the VOF model in multiphase flow to introduce bubbles into the pump. The simulation results were analyzed to determine the flow trajectory of individual bubbles in the flow field, the bubble crushing law, and to predict the region where cavitation occurs [9].