Numerical Investigation on the Transient Cavitating Flow Inside a Torque Converter

Torque converters are key components in automatic transmissions used in vehicles, construction machinery, etc. The development of hydraulic torque converter is toward high capacity, high speed and high power-weight ratio, which requires higher mass flow rate, leading to higher risk for cavitation. Cavitation is a transient phenomenon which involves phase exchange between liquid and vapor, and heavy cavitation in torque converter brings about severe performance degradation, noise, vibration and even failure depending on the degrees of cavitation. However, as torque converter is a closed-loop multi-component turbomachinery, it’s hard to have access to the internal cavitating flows. Thus, the transient cavitating flow behavior remains unclear. Therefore, this study investigated the dynamic cavitating flows inside a torque converter using transient multiphase computational fluid dynamics (CFD) model. The effects of cavitation on the hydraulic performance and the evolution mechanism of cavitation in the torque converter were investigated, and the numerical model is validated against test data. The proposed transient CFD model was able to predict the cavitation characteristics with reasonable accuracy. The results indicated that cavitation mainly occurred in the stator domain, and it brought about over 20% degradation in torque capacity.