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Wet-running multi-plate clutches and brakes are important components of modern powershift gearboxes and industrial powertrains. In the open stage, drag losses occur due to fluid shear. The identification of drag losses is possible by experiment or CFD-simulation. For the calculation of the complex fluid flow of an open clutch, CFD-approaches such as the volume of fluid (vof) method or the Singhal cavitation model are applicable. Every method has its own specific characteristics. This contribution sets up CFD-calculation models for different clutches with diverse groove designs. We present results of calculations in various operating conditions obtained from the Singhal cavitation model and the vof method. The usage of modern commercial CFD-Tools (Simerics MP+) results in short calculation times.

During a special scientific project (SFB 365), supported by the DFG, a parallel hybrid concept for passenger cars, called the Autark Hybrid, was developed, assembled and investigated. The drive line consists an electric engine supplied by a 120V-Ni/MH-battery for about 30 km electrical driving distance and a turbo diesel engine. Both engines use the same gearbox, the i2-gearbox, which is specially designed to have a wide spreading. Significant fuel savings are achieved by recuperation of kinetic energy and by avoidance of inefficient operation of the ic-engine at areas of low power demand. The results from the research project concerning fuel consumption, respectively fuel saving will be presented and discussed in this paper. The adjustment between simulation and test rig investigations shows problems by the practical realisation of operation strategy and operation mode of the powertrain elements. As result smaller fuel savings can be realised than predicted.