Abstract
The purpose of this study is improvement of spray characteristics of the nozzle, which was developed in this previous study, for a direct injection Diesel engine. The nozzle which was used in this study is that excellent combustion characteristics are obtained by only changing geometric shapes of the multi hole nozzle, that is, inlet and outlet shapes of nozzle holes, hole diameter, hole length and pitch circle diameter of nozzle holes. In this study, effect of geometric shapes of the nozzle developed in this study on atomization characteristics was investigated. As a result, it was cleared that when round inlet and outlet shapes of the nozzle holes were used, atomization characteristics were improved significantly compared with the sharp inlet shape nozzle. Moreover, it was found that in case of the nozzle without hole length of round inlet shape nozzle, breakup length, that is, liquid core length, becomes short about 50 % and spray angle becomes large about 50 % compared with the sharp inlet shape nozzle.
