Abstract
The characteristics of fuel spray behavior are very important for diesel ignition and combustion process which significantly affect on the engine performance and exhaust emissions. In the up-to-date direct injection diesel engine technological innovations have been considerable. Especially, the injection system such as multi-stage injection and high-pressure injection is significant and then the combustion process has considered to differ from the combustion process of the conventional diesel engine substantially. In this study, using the constant volume vessel, which can simulate the temperature and pressure in the combustion chamber at the time of the fuel injection of direct injection diesel engine and a high speed video camera, the observations of fuel spray, mixture formation and combustion process have been made. On the experiments, the injection system using a piezo-actuator to get a same injection sequence of multi-stage injection in the modern direct injection diesel engine was used to realize a single shot and multi-stage injection in the constant volume vessel. The piezo-actuator using in the injection system with high speed and high load characteristics operate directly nozzle needle. The observations of the spray and combustion process were made on the conditions of different injection rate patterns includeing single shot injections and multi-stage injections.
