Influence of plume arrangement on spray collapsing process in lateral-cylinder-mounted gasoline injectors

Spray collapsing is a major factor that deteriorates combustion performance in gasoline direct-injection (GDI) engines. This study employed three different GDI injectors to investigate plume arrangement influence on spray dynamics. Novel optical diagnostics were applied to analyze complex spray collapse behaviors using LED-based diffusive back-illuminated extinction imaging (DBIEI) and 3D computed tomographic (CT) image reconstruction. The triangular pattern with 6 holes, commonly applied in modern GDI engines, was compared with two newly designed spray patterns: the inversed T pattern with 6 holes and the lambda pattern with 5 holes. Experimental results showed that the base triangular pattern, with plumes enclosed by other plumes, indicated significant spray collapse behavior under various conditions. The inversed T pattern, where plumes were arranged to not have a closed volume, had a robustness against collapse due to an open layout which prevents imbalance of the local pressure field that may causes collapse. The lambda pattern, which had a similar plume arrangement to the triangular pattern, except that one side of the diamond-shape closed volume is opened, also showed good robustness against collapse under most of the test conditions. This study demonstrated that spray collapse can be significantly mitigated by improved plume arrangement and provides spray patterns that can be applied to actual GDI engines with significantly improved spray robustness.