# Identification and Optimization Study of Cavitation in High Power Torque Converter
###### Abstract
[PERSON], from Michigan Technological University, implemented an automated dynamometer test cell with a specially designed torque converter test chamber, and, using near acoustic field identification method to identifies cavitation through the filtered sound pressure level (SPL) generated by the collapse of cavitation bubbles in the torque converter [10], revealed the relationships between the torque converter design and operating parameters and the sound power of cavitation noise. This process, however, requires the introduction of professional noise detection equipment as well as identification methods. The complexity of cavitation noise components adds to the challenge, and its identification involves a certain degree of subjectivity. To optimize cavitation, [PERSON] from Michigan Technological University fixed a sensor directly onto the impeller. He then used a microwave telemetry system to study the pressure of the blade and designed a notch in the form of the tail of the impeller to improve the cavitation phenomenon [11]. [PERSON], [PERSON], and their colleagues from Beijing University of Technology in China conducted a transient analysis of two-phase flow using CFD. They found that cavitation is prone to occur in the head region of the stator. To address this issue, they designed overflow holes for the head of the stator, which reduced the vortices on the suction surface of the blades and optimized the cavitation. This study was documented in reference [12]. [PERSON] from Jilin University in China proposed a vortex control method to weaken cavitation in the torque converter. The method is based on a leading-edge bionic convex junction and is combined with optimal Latin Hypercubic testing and a multi-objective optimization approach to design the convex junction with the appropriate wavelength and amplitude [13]. [PERSON] et al. from Wuhan University of Science and Technology in China reconstructed the stator blades using Joukowsky airfoil transformation. They optimized the curvature change rate of the stator to ensure that its flow line is consistent with the hydrodynamic characteristics, which reduces the probability of cavitation. The study is cited in reference [14]. This paper presents a study on the phenomenon of easy cavitation of high-power torque converters. Firstly, CFD simulation analysis and experimental studies were conducted to identify the rules of cavitation occurrence. Then, the simulation results were compared with the test results to determine the speed ratio region where cavitation occurs in the torque converter. Finally, the flow field of the stator was analyzed to identify the key factors that affect cavitation. The optimized design of the torque converter stator is achieved by adjusting the key parameters of the stator vane bobbin line without modifying the pump, turbine, and torus. The nominal torque of the torque converter is greatly improved in the region of large load and low speed ratio under the test condition, with the torque ratio remaining basically unchanged and the maximum efficiency slightly decreased. Specifically, the nominal torque at zero speed has been increased from 735.6 N\(\cdot\)m to 946.8 N\(\cdot\)m, resulting in a 28.7% increase in the nominal torque rate. The occurrence of cavitation is minimal when the speed ratio is less than 0.15, and this improvement greatly reduces the risk of cavitation in the high-torque torque converter.