Tolga Uhlmann

Turbocharger Bearing Friction Measurement and Simulation

Turbocharger (TC) bearing friction mostly affects the “low speed” operation of the turbocharger and is therefore relevant for the transient response and part load emissions of modern combustion engines. Further optimization of TC friction has to be supported by sophisticated simulation tools to shorten developmental time and reducing the costs for prototyping and testing.

An extended calculation approach of exhaust thermocouple temperatures in one-dimensional gas exchange simulation for turbocharged gasoline direct-injection engines

A new model approach is presented to determine exhaust thermocouple temperatures in gas exchange calculations for turbocharged gasoline direct-injection engines. Since the measured thermocouple temperature at turbine inlet is typically used as a criterion to fix the required fuel enrichment for turbocharger protection, an accurate prediction of this value is decisive in the development of future engine concepts. Therefore, a detailed one-dimensional thermocouple model has been developed which captures the measurement principle by a physical approach. The major advantage of this approach is the integration of detailed data of convective heat transfer along the thermocouple protrusion length from three-dimensional computational fluid dynamic exhaust flow simulations. Detailed investigations by means of three-dimensional and one-dimensional simulations are presented for steady-state flow as well as in full and part load operations of four turbocharged gasoline direct-injection engines. For further verification, the test carriers have been equipped with special temperature measurement technology like various thermocouple penetration lengths and profile thermocouples. A comparison with measured temperatures shows that at turbine inlet, a prediction deviation of less than 10 K can be achieved with the detailed one-dimensional model.

Elektrische Zusatzaufladung - neue Freiheitsgrade durch höhere Bordnetzspannungen

Die elektrisch angetriebene Aufladung ist bereits seit vielen Jahren immer wieder Gegenstand von Untersuchungen im Fahrzeugsektor. Sowohl Fahrzeughersteller als auch Zulieferer haben verschiedene Konzepte vorgestellt. Dem Konzept des elektrisch angetriebenen Verdichters in Kombination mit einem Abgasturbolader (TC) werden hierbei die grosten Erfolgschancen eingeraumt.

Extreme downsizing for gasoline engines – fun to drive with extremely low emissions

This paper elaborates different boosting systems for extreme downsizing levels considering the target of optimal transient performance: