High-resolution 3D CFD multiphase simulation of the flow and the drag torque of wet clutch discs considering free surfaces

The viscous shearing of the cooling oil within disengaged wet clutches causes a substantial amount of power loss. In order to optimise efficiency, it is the objective of current research to minimise these losses to a great extent. In addition to test rig measurements effective calculation tools are desirable. This contribution deals with highly detailed numerical simulation of the flow in disengaged wet clutch discs with radial and complex groove designs. For this purpose a transient 3D CFD simulation model is presented. The calculation results are compared with test rig measurements and high-speed video recordings of the phase distribution. By variation of the operating conditions as well as various geometric parameters, the general validity of the model is shown.