ISBN 9783843902465

978-3-8439-0246-5, Reihe Fahrzeugtechnik

Jasper Kammeyer
Abgasturbolader mit Deckband zur Verringerung der turbinenseitigen Spaltverluste

261 Seiten, Dissertation Universität Hannover (2011), Softcover, A5

Zusammenfassung / Abstract

Legislation forces the automotive industry to develop technologies for sustainable and environmentally friendly mobility. The downsizing of internal combustion engines in combination with turbocharging represents a pioneering approach to meet future standards. The thesis of this work is to reduce tip-leakage losses of downsizing turbocharger turbines by a shrouded turbine wheel and thus contribute to the needed improvements in fuel economy, emissions and driveability of modern downsizing engines.

Initially a potential analysis of tip-gap related losses in small turbocharger turbines is carried out. First time, the tip-leakage flow of small radial turbines is described in detail. As a result of the potential analysis an empirical 1D tip-leakage loss model is developed. It is found, that the tip-gap related efficiency losses in small radial turbines account for up to 7 percentage points. In order to utilize some of this potential, first time a shrouded turbine wheel for downsizing turbochargers is developed. The experimental investigations of shrouded turbines on a turbocharger test facility show improved levels of efficiency of up to 6 percentage points as well as an improved turbocharger dynamic response. The measured efficiency increase shows a thermal and aerodynamic portion, both contributing to approximately equal parts. The thermal portion results from an insulating impact between turbine flow and turbine housing due to the shroud. The aerodynamic portion results from changes of tip-leakage flow.

The positive characteristics of the shrouded turbine are accompanied with increased centrifugal forces. As a part of this work a significant increase of the maximum operating speed was enabled by an improved manufacturing process of prototypes.