Design and development of a new gasoline direct swirl injector

摘要

Numerical and experimental analyses were carried out to design and develop the optimum geometry of a gasoline direct swirl injector. In the numerical analysis, the needle cone angle, swirler inclined angle and needle lift were changed with mass flowrate as design parameters to determine the optimum sizes. The critical sizes of the needle cone angle, swirler inclined angle and needle lift are 140°, 120° and 100μm respectively. Thus, the optimum sizes may be 130°, 110° and 80μm respectively. Experiments were performed to observe spray phenomena and to measure the dynamic flowrate, penetration of the spray tip and mainstream, spray angle and the mean drop diameter using an image processing method. The formation of a counter-rotating vortex appears in the steady state as a feature of the high pressure swirl injector spray. The calculated needle cone and swirl inclined angles as well as the cone-type needle reduce the non-swirl and sac volumes of the non-swirl region such that the reduced volumes restrict the penetration of the spray tip. The sizes of the mean drop diameter range from 20μm to 23 μm and the spray angles range from 64° to 66°, which satisfy the requirements of a gasoline direct injection engine.