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Title: Eccentric needle motion effect on near-nozzle dynamics of diesel spray

Here, the eccentric needle motion has been regarded as an important cause of in-nozzle flow disturbances and hole-to-hole spray variations of modern fuel injectors. However, the experimental investigations on this subject have rarely been reported due to great difficulties in the direct measurements of eccentric needle motion and the flow characteristics of individual holes in an injection nozzle. In this study, the axial and eccentric needle motion and the ear-nozzle spray dynamics of 3-hole, 5-hole and 8-hole diesel injection nozzles were investigated in varied injection pressure conditions using an xray phase-contrast imaging technique. The eccentric needle motion and near-nozzle spray axial velocity showed temporal oscillations during the injection with different oscillation frequencies. The frequencies of these two oscillations were independent to the nozzle and injection pressure. To discuss the mutual dependency of these two oscillations, the time traces of the spray axial velocity were measured for individual holes. The results showed that the oscillation phase, frequency and amplitude of the spray axial velocity were almost identical for all holes, which indicated that the sac pressure variation rather than hole-to-hole flow variation can be the primary cause of the spray axial velocity oscillation by the eccentric needle motion. The adequacy ofmore » this consideration was thoroughly discussed using a mass balance model in the nozzle sac that predicted the sac pressure variation during an injection event.« less
 [1] ;  [1] ;  [2] ;  [2] ;  [2]
  1. National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 206; Journal Issue: C; Journal ID: ISSN 0016-2361
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Isuzu Motors Ltd.; USDOE
Country of Publication:
United States
42 ENGINEERING; diesel injector; diesel spray; eccentric needle motion; spray axial velocity; X-ray phase-contrast imaging
OSTI Identifier: