Abstract
Keywords: Turbocharger, Transient, Air-Assist
One of the most important challenges facing the modern engine development engineers is to improve the vehicle economy and reduce the levels of green house gas emissions. Car manufactures are keen to improve in both these areas. In Europe through the ACEA agreement (Sauer, 2005) manufactures agreed to meet a new vehicle fleet average CO2 emissions level of 140g/km. Also European Union has set a new target namely `Euro V´ which automotive manufacturers need to achieve by 2008 (Euractiv, 2006). This will be followed by `Euro VI´ which will further restrict the outputs of harmful emissions (European Federation of Transport and the Environment).
A method of reducing the harmful emissions of an Internal Combustion (IC) engines is to use a turbocharger. A turbocharger utilises energy from the exhaust gases and uses it to pressurise the air at the inlet to the cylinders. This allows for the density of air in the cylinder to be greater than the density of ambient air. This allows more power to be produced for a given size of an engine. It has also been shown that use of turbochargers results in reduction the harmful emissions of an engine (Lefebrve, 2005).