Flow and Combustion in a Transparent 1.9 Litre Direct Injection Diesel Engine

Abstract

Two identical 1.9 litre direct injection (DI) diesel engines having optical access for application of laser diagnostics were operated at Volkswagen and Imperial College as part of the European programme (IDEA) on diesel engines. A variety of complementary laser-based techniques were used to characterize the flow-generating capacity of the intake system under steady flow conditions, the in-cylinder flow during induction and compression as well as the spray development, auto-ignition and combustion under three typical engine operating conditions. The most important results of this programme are presented and discussed here in view of their implications for improved combustion and reduction of exhaust emissions in small direct injection diesel engines, through better matching of the spray characteristics with the in-cylinder flow as a function of engine speed and load. The results were obtained in sufficient detail to allow validation of the multi-dimensional computer code developed within the IDEA programme.