Abstract
Experimental investigations of primary spray structure very close to nozzle of practical high-pressure swirl injector, which is used in gasoline direct injection (GDI) engine, were carried out. Visualizations of primary spray structure were demonstrated using a high-speed video camera with a long-distance microscope. Evaluation of system performance was investigated. Three kinds of light source, such as metal-halido lump, laser beam and laser sheet of Ar-ion laser were applied. Strong intensity of the light source is needed to obtain the image with very high camera speed. Moreover, initial state and development of the spray of the swirl injector were discussed. It has been shown that the liquid fuel column without swirl motion was injected as a compact jet at the beginning of the injection. During the injection period, the spray indicates the quasi-steady state mode. Liquid sheet from the nozzle exit has a ligament structure. Using Ar-ion laser sheet and high-speed camera, length and thickness of the liquid sheet can be measured.
