Effects of cavitation on performance of automotive torque converter

Jaewon Ju,Je Hyun Baek,Jaedeuk Jang,Minsuk Choi

doi:10.1177/1687814016654045

Abstract

Cavitation is a phenomenon whereby vapor bubbles of a flowing liquid are formed in a local region where the pressure of the liquid is below its vapor pressure. It is well known that cavitation in torque converters occurs frequently when a car with an automatic transmission makes an abrupt start. Cavitation is closely related to a performance drop and noise generation at a specific operating condition in a car and a torque converter itself. This study addressed the relation between cavitation and performance in an automotive torque converter in a quantitative and qualitative manner using numerical simulations. The cavitation was calculated at various operating conditions using a commercial flow solver with the homogeneous cavitation model, and the torque converter performance was compared with the experimental data. Numerical results well match to the data and indicate that the cavitation causes significant performance drop, as the pump speed increases or both speed ratio and reference pressure decrease.

Highlights

A torque converter is a fluid coupling device used for transferring rotating power from an engine to an automatic transmission
A torque converter is usually composed of three parts: pump driven by the engine, turbine driving the transmission, and stator mounted on an overrunning clutch positioned between the pump and turbine
An internal fluid circulating through the three components can vaporize locally to form bubbles at a specific operating condition where the static pressure goes below its vapor pressure

Summary

Introduction

A torque converter is a fluid coupling device used for transferring rotating power from an engine to an automatic transmission. Dong et al.[9] found from their numerical results that the cavitation on the leading edge of the stator grows in size with the increasing pump speed, resulting in large performance drop in a torque converter.

Results

Conclusion