[EN] The purpose of this study is to improve the spray characteristics of a direct injection Diesel nozzle. Spray
atomization of the multi-hole atomization enhancement nozzle, which was invented in previous studies, is explored.
The aim is to improve and obtain excellent spray characteristics. The effects of different nozzle geometries and
dimensions on spray characteristics are investigated, including chamfered and rounded nozzle hole inlets and a
multi-hole atomization enhancement nozzles. It is found that the multi-hole atomization enhancement nozzle with
a rounded chamfered inlet is effective in achieving a high-dispersion spray, a large spray angle and small droplets.
However, it should be noted that the spray is significantly atomized and a large number of small droplets as
suspended as a mist. The photographic images of the spray are taken against a white background and the
boundaries between the ejected spray and the background are indistinct. Furthermore, the breakup length is short
at 3 mm for a hole diameter of 0.3 mm, the spray angle is about 70° and the Sauter mean diameter decreases
dramatically to 15 μm at a low injection pressure of 10 MPa, This research was partly supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (C) Grant Number 15K05847 and also partly supported by the Ministry of Education, Culture, Sports, Science and Technology (MEWT) MEXT-Supported Program for the Strategic Research Foundation at Private Universities. The authors wish to express their thanks for the supporting for this research.