An investigation into the effect of the piston-liner interface upon the particulate emissions from a turbo charged diesel engine.

The continuing tightening of emission regulations has encouraged extensive research into fuel spray vaporising and combustion. This thesis is an investigation into the effect that the cylinder boundaries have upon the quantity and composition of the unburnt hydrocarbons present in the exhaust gas and particulate matter. To determine the cylinder boundaries' effect on the exhaust hydrocarbon content a series of engine tests was completed. The engine used for these experiments was a modem four cylinder turbo charged direct injection diesel engine, operated at five steady state test points. The test consisted of two standard engine builds to determine the accuracy of measurement and to supply a base point for comparison. The second test used standard pistons with modified oil control rings to increase the oil film thickness. The final test used pistons with the top ring moved nearer the top of the piston by 5.5 mm to reduce the top land crevice volume by ?55%.The composition of the particulate soluble organic fraction (SOF) for the test using the low tangential load oil control piston ring was shown to have a greater fuel content than for other tests, showing that adsorption of the fuel in the lubricating oil contributes to the particulate. The reduction of the top ring crevice volume produced similar quantities of particulate SOF but it consisted of generally lighter hydrocarbon species.The effects of these changes were replicated in a mathematical model which calculated the in cylinder values for fuel, soot, temperature and hydrocarbons. The model also simulated the oxidation of hydrocarbons at the cylinder boundary and consisted of 3 primary zones; the combustion chamber, crevice volume and oil film.This research shows that careful design of engine components can influence the quantity and composition of the particulates exhaust gas and allow the reduction of regulated components.