ABSTRACT
Flow inside the diesel nozzle is crucial to spray, combustion, and emissions. This work aimed to improve the understanding of effects of internal fuel-flow on diesel spray, especially the special string cavitating flow. Optical experiments were employed for characterizing the formation of string cavitation inside the transparent scaled-up tapered diesel orifices. Simultaneously, the corresponding evolution of spray cone angles were obtained. Results show that there were two origins of the string cavitation, which were originated from inlet and outlet of the orifice, respectively. Moreover, there were two typical development processes of the string cavitation between hole and hole, which were defined as type-A and type-B string cavitation. Furthermore, effects of string cavitation were analyzed: it could trigger the geometry-induced cavitation and make a sharp increase of spray cone angle. Finally, the relationships between the occurrence regularity of string cavitation, the needle lift and the injection pressure were revealed by comparison of different needle lifts and different injection pressures.
KEYWORDS
PAPER SUBMITTED: 2018-04-05
PAPER REVISED: 2018-12-06
PAPER ACCEPTED: 2018-12-11
PUBLISHED ONLINE: 2019-01-13
THERMAL SCIENCE YEAR
2020, VOLUME
24, ISSUE
Issue 1, PAGES [193 - 201]
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