Numerical Computation of the Air Flow and the Thermal Behavior of a Double Dry Clutch Automotive Transmission 2015-01-1661

New directives and increasing competition push OEMs to get better performances (engine power increase), along with mass and size reduction (consumption). These evolutions lead to an increase of the thermal solicitations undergo by the clutches whereas their weight must be decreased, as it is one of the main influent factor on CO2 emissions. As the compactness is even more reduced for a Double Dry Clutch (DDC), this issue is critical.

In order to improve the thermal behavior of the DDC, a CFD study has been performed. The present paper will introduce the first results obtained with a validated CFD model. The computations are performed on a DDC where the air flow around the rotating parts, along with the convection and the conduction of all solid parts are modeled. Then four different cases are used to evaluate the impact of holes on the air flow path and on the thermal behavior of the different parts of the system. The global and local air flow results are then determined in addition with the heat transfer coefficients. Results show that the heat transfer coefficients are mainly piloted by the local air flow. Moreover, it shows that large temperature differences can occur between the different cases, and that a design improvement can be proposed regarding pressure plates cooling.