Effects of wall impingement conditions on spray atomization and wall-wetting for a direct injection spark ignition (DISI) system

Abstract

This study was performed to investigate the effects of injection pressure on spray development characteristics wall impingement on the top of piston for various engine operating conditions. Spray visualizations were conducted using a high-speed camera under mid-load and high-load conditions. In the present study, fuel spray impingement on the top of piston was calculated based on the spray images and piston location. Results show that the wall impingement of the injected fuel occurs at the late injection timing at the end of the compression stroke and early injection timing at the beginning of the intake stroke. To prevent the wall impingement, the injection timing should be advanced as the engine speed increases. There is no significant difference in the zero-impingement injection timing region where the wall impingement does not occur even when the engine speed changes. The method proposed in this study can be used to predict the amount of wall impingement of the fuel spray on various cylinder design parameters and engine operating conditions.