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Author Cao, Yujun ♦ Idlahcen, Saïd ♦ Blaisot, J. -B ♦ Rozé, Claude ♦ Méès, Loïc ♦ Maligne, David ♦ Blaisot, Jean-Bernard
Source Hyper Articles en Ligne (HAL)
Content type Text
File Format PDF
Language English
Subject Keyword diesel injection ♦ index matching ♦ backlight ♦ liquid interface tracking ♦ frequency of cavitation ♦ spi ♦ Engineering Sciences [physics]/Reactive fluid environment ♦ Engineering Sciences [physics]/Optics / Photonic
Abstract Cavitation inception is very sensitive to the nozzle geometry. Two diesel-like transparent nozzles with sharp and round inlet edge were investigated under moderate injection pressure. By means of backlight imaging technique, images were recorded in two regions near the orifice: within ten orifice diameter downstream the nozzle and inside the nozzle, for different times after start of the injection. A cross-correlation technique was applied to images downstream the orifice to estimate the average velocity of the spray. The development of the spray was studied at the transient and full-opened stage, related to the needle lift motion. To analyse the flow inside the nozzle, the relative size of the vapour pockets was measured on the image and the relative frequency of the occurrence of cavitation was determined over image series. This approach permits to examine the time variation of the cavitation occurrence from the inlet to the outlet of the orifice. The results highlight the sensitivity of the cavitating flow to the shape of the inlet edge. Moreover, the trends of the variation over time of the velocity and of the cavitation frequency are very similar to each other but different for each geometry, indicating that the characteristics of the diesel spray in the near field is closely affected by the way cavitation is developing in the nozzle.
Educational Use Research
Learning Resource Type Proceeding
Publisher Date 2017-08-01