Investigation of Macroscopic as well as Microscopic Spray Behavior of Multi-hole GDI Injector under Engine Like Hot Injector Body Conditions

Fuel injection is one of the most important processes in the GDI engine operation. Depending when the fuel is injected in the GDI engine, it can either work in homogeneous or stratified charge mode. In case of real engine operation, fuel injector gets heated due to heat transfer from the in-cylinder hot burnt gases. This can significantly affect the spray characteristics and ultimately the engine performance. In the present work, engine like hot injector body conditions have been created in a constant volume spray chamber. Five different temperatures conditions (23 °C, 100 °C, 150 °C, 200 °C and 250 °C) were created to study the effect of hot fuel conditions. Schlieren and Shadowgraph techniques were used to capture the vapor and the liquid phase of Isooctane, whereas droplet size information was measured using the Phase Doppler Particle Analyzer (PDPA). Results showed that with increase in fuel temperature, spray collapsed towards the injector axis due to flash boiling of the fuel. This spray collapse was quantified by measuring the overall spray cone angle of the liquid phase. It was observed that spray cone angle decreases drastically with increase in injector body temperature. Additionally, droplet size showed large reduction in SMD and AMD although fuel injection pressure was reduced from 100 bar to 40 bar. The liquid and the vapor penetration lengths were observed to be higher under hot injector body conditions