Investigation on the effect of ventilation on string cavitation patterns in diesel nozzles

Abstract

Aiming at the complicated vortex problem that affects the flow stability of diesel engine nozzles, this paper focuses on the effect of ventilation on the string cavitation patterns in the nozzle hole with a self-built scale-up test bench. Hole-to-hole string cavitation is not stable without bubbles, and the ventilation can improve the situation. Relatively speaking, the position of hole-to-hole string cavitation in the SAC volume changes significantly with the bubble content. In contrast, the needle-originated string cavitation is stable in the vortex channel. Only if there are many bubbles, the cavitation pattern changes to hole-to-hole string cavitation or string cavitation originating from the upper wall of the hole inlet. At this point, the corresponding atomization morphology changes, and the spray angle decreases significantly. It is verified that there is a one-to-one correspondence between the cavitating pattern and the spray angle near the hole.