The effect of reactor blade geometry on the performance of an automotive torque converter

The performance characteristic of a torque converter strongly depends on the reactor blade geometry, which directly affects its torque ratio and input capacity factor. We investigated the effect of the reactor blade geometry with varying thickness ratios and scroll angles on the performance of a torque converter. Using a previously developed design software, TorconMaster ^®, several reactor blades were newly generated with varying thickness ratios and scroll angles. Their performance characteristics were analyzed by numerical analysis. The present numerical analysis considered the details of the full three-dimensional, viscous and turbulent flow field within the automotive torque converter adopting a mixing plane model and showed good agreement with experimental results. The numerical results provided refined relationships between geometry and performance. As the thickness ratio of the reactor blade decreases, the input capacity factor increases but flow separation occurs in the low speed ratio region, resulting in the so-called "sag" phenomenon. In addition, the decrease of scroll angle resulted in a significant increase of the input capacity factor and a slight decrease of torque ratio. Therefore, the variation of geometrical parameters in a reactor blade can be used for tuning the performance of the torque converter.