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This paper will focus on fuel flow analysis in nozzles, in particular, in the injection hole, a key component of Fuel Injection Equipment(FIE). Optimum controlled flow in the hole improves flow efficiency and atomization. To meet the emission regulations which will be introduced from the end of '90's to the 21st century, Diesel Engines require FIE to produce higher injection pressure which creates better atomization and higher utilization of air. But higher injection pressure results in increased pump driving torque, larger pump size and higher cost. We have studied the improvement in fuel flow characteristics of the nozzle, using an enlarged flow model and the theoretical analysis method. As a result, we have found that the cavitation, which occurs at the inlet of the hole, is affected by the configuration of the sac hole and injection hole. And, furthermore, the cavitation has a direct effect on the contraction and its recovery flow.

This paper reports on research conducted at Nippondenso Co., Ltd. and Meiji University on nozzles for heavy duty diesel engines. It focuses on fuel flow analysis in the nozzle, a key component of Fuel Injection Systems (FIS). The optimum design nozzle improves fuel flow and spray characteristics. A newer and tougher emission regulation from the EPA for heavy duty diesel engines will be inevitable from 1998 onward. The goal of every company is to design new FIS in advance which meet the regulations of the future rather than paying for expensive developing costs after new laws have come into effect. To meet the regulation, requirements for FIS are higher injection pressure and injection rate control which create better fuel spray atomization and higher utilization of air. In particular, the nozzle must ensure that high injection pressure is effectively converted to fuel spray without pressure losses.