Numerical Study on the Internal Flow and Torque in Variable Capacity Type Fluid Coupling

Abstract

The internal unsteady flow in the variable capacity type fluid coupling is analyzed by CFD, considering the movement of free-surface. The torque curve of CFD shows good agreement of experimental one. The fluctuation of torque is almost similar when the chamber is filled by the fluid. When it is partially filled, fluctuation has another pattern at larger speed ratio. The numerical result shows that there are two different flow patterns. In a pattern, most of working fluid is rotating in the rotor area, and fluid transfers small torque only. In another pattern, the working fluid rotates around the air area, that is concentrated at the center of fluid coupling, and fluid can translates large torque. In the area of instability of the fluid coupling, where the torque and rotational speed varies very much in the experiment, flow seems to go around between these two flow patterns.