Quantification of primary flows of a torque converter using laser doppler velocimetry

All modern automotive automatic transmissions require the use of a torque converter to allow for the transmission of torque from the engine to the drivetrain. Although they are commonly used throughout the automotive industry, there is little understanding of the internal flows within the torque converter. An experimental study has been conducted to reveal the internal flow characteristics within a production torque converter using Laser Doppler Velocimetry (LDV) under the operating conditions.

LDV measurements were conducted on the planes between impeller blades, and the gap between the impeller and turbine blades. The study showed that the internal flow is highly complex and the difference in rotor speeds between the impeller and turbine compound the flow effects. Transmission oil flows in the planes at the impeller exit and gap region were affected by the turbine blade as it passed. Transmission oil flow was also found to be leaving the impeller and flowing over the turbine into behind the turbine back plate. This affected the converter efficiency negatively.

This study has led to a better understanding of flow mechanism within the torque converter and provided the guidance needed for the advancement of improved computational fluid dynamic models.