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| Influence of Needle Valve Movement on Cavitation and Ingestion in Nozzle at the End of Injection |
| DOI：10.13949/j.cnki.nrjgc.2019.04.005 |
| Key Words:injector nozzle end of injection valve movement ingestion cavitation |
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| Abstract:Based on the volume of fluid method and overlapped grid technology, the fuel flow characteristics in a diesel engine injector nozzle during the ending of injection were studied through the three-dimensional simulation. The cavitation and ingestion in a transparent nozzle before and after the end of injection were investigated by visual experiment, and the effect of needle valve movement on the cavitation and ingestion was analyzed. The experimental results were consistent with those of the simulation. The results showed that during the seating process of the needle valve, the cavitation at the orifice was earlier than that at the pressure chamber, but the maximum cavitation at the pressure chamber was larger than that at the orifice. A quantitative analysis of the cavitation and ingestion indicated that the collapse of the cavitation was the direct cause of the ingestion. At the same time, the cavitation and ingestion in three nozzles of different needle valve seating speeds were also simulated. The results show that the cavitation at the pressure chambers of the three nozzles is different, showing that the cavitation increases with the increase of the needle valve moving speed; and the cavitation at the orifices of the three nozzles is basically equal. Finally, a new value reflecting the cavitation in a nozzle during the ending of injection was derived by a theoretical derivation, which can be used to explain the mechanism of cavitation generation in a nozzle and the influence of the needle valve movement on the cavitation and ingestion in a nozzle. |
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