Numerical simulation and experimental investigation of early development of the combustion process in a direct-injection spark-ignition engine

UV-visible natural emission digital imaging is applied in the optically accessible combustion chamber of a direct injection spark ignition 8DISI) engine. the engine is equipped with the four-valve head and the same injection system of a commrcial turbocharged engine. Optical accessibility is obtained through a quartz window placed on the piston head. Numerical silulations are performed by means of a 3D model developed with the AVL fire tm environment, which exploits ad in-house developed model for spray dynamics. the aim of work is the better understanding of the physical and chemical processes characterising the mixture formation and combustion preocesses. tests are carries out using commercial gasoline. the injection timing and duration are fixed in order to obatain lean homogeneous combustion condition. The effects of the ignition timing on the characteristic flame development angle, namely on the flame inition and propagation, are analysed.