Investigation of Flow Characteristics in a Fluid Coupling of Variable Capacity Type

A fluid coupling of variable capacity type is able to attain continuous change of rotational speed by changing the fluid capacity, and is widely used as the maximum efficiency amounts to 95～98%. However, the flow characteristics in the coupling are not well understood, since the liquid and gas co-exit in the coupling chamber, resulting in a very complicated rotating two-phase flow. The present study is aimed to show the flow behavior in a variable capacity type fluid coupling, and the flow was visualized by use of taft method and oil film method and the flow characteristics were determined experimentally. The special interest was focused on the behavior of gas in a rotating chamber and internal flow characteristics. The pressure variation on the runner vane was measured and the change of both transmitted torque ratio and overall performances were discussed