年間 6 号発行
ISSN 印刷: 2152-5102
ISSN オンライン: 2152-5110
Indexed in
Characterization of Cavitation Flow in a Simple Hole Nozzle
要約
The liquid fuel flow in a nozzle hole is thought to be closely related to the breakup processes of the spray by pressure type atomization. Typical applications of this type of atomization are seen in diesel and direct injection gasoline injectors. In this study, experiments were made for clarifying the relation between the internal flow of the nozzle hole, especially the flow with cavitation bubbles, and the breakup process of the spray. A simply shaped nozzle, which had a single hole 0.5 mm in diameter and was made of transparent acrylic resin, was used for observing the internal flow of the nozzle hole. Water pressurized in an accumulator was injected from the nozzle. In addition to the observation of the internal flow of the nozzle hole and the liquid jet injected from the nozzle, measurements were made of the discharge coefficient, the acoustic intensity and the impedance of the internal flow of the nozzle hole. Variations in the discharge coefficient, the acoustic intensity and the impedance with the differential pressure of the injection are closely related to the growth and collapse of cavitation bubbles in the internal flow of the nozzle hole. The acoustic intensity increases especially in the high frequency range when the cavitation bubbles develop with the differential pressure of the injection, and the peaks of the acoustic intensity in the high frequency range disappear when the cavitation bubbles largely develop and a hydraulic flip occurs. Also the impedance increases suddenly by the detachment of the liquid surface from the inner wall.
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