Search Results

The flow within the disengaged wet clutch packs of an automatic transmission has been simulated as a three-dimensional, steady-state, two-phase flow using the commercial computational fluid dynamics (CFD) code FLUENT. The flow within a clutch with ungrooved friction plates was first solved for validating the CFD model, followed by a simulation of the flow within a clutch with grooved friction plates. A group of dimensionless variables have been established for mathematically modeling the drag torque and power loss in clutch packs. The effects of rotating speed of friction plate, pack clearance, and flow rate on drag torque and power loss have been studied.

An impinging-flow based methodology of enhancing the heat transfer in the grooves of a lockup clutch is proposed and studied. In order to evaluate its efficacy and reveal the mechanism, the three-dimensional flow within the groove was solved as a conjugate heat transfer problem in a rotating reference frame using the commercial CFD code FLUENT. The turbulence characteristics were predicted using k-ε model. The comparison of cooling effect was made between a simple baseline groove pattern and a typical flow-impingement based groove pattern of the same groove-to-total area ratio in terms of heat rejection ratio, maximum surface temperature, and heat transfer coefficient. It is found that more heat can be rejected with the impinging-flow based groove from the friction surface than with the baseline while the maximum surface temperature is lower in the former case.