For improving DI diesel engine performance, such as lower nitrogen oxidant (NOx), particulate molecular (PM) emission and higher output, etc., atomization of the fuel spray plays an important role. In order to obtain better fuel atomization without increasing the fuel injection pressure, increasing the flow velocity at the injection nozzle spray holes is regarded as an effective way. Through experiments, enlarging the chamfer at the spray hole inlet proved to be the most effective and suitable method for establishing high flow velocity injection nozzles.
We have compared the high flow velocity injection nozzles with conventional nozzles in terms of injection characteristics and fuel spray characteristics, and confirmed the improved fuel spray atomization with the high flow velocity injection nozzles.
Finally the high flow velocity injection nozzles were tested on a medium duty class, natural aspirated DI diesel engine. Here the high flow velocity injection nozzle displayed improved NOx-PM trade off characteristics and higher engine output, and proved to be an effective method for engine improvement.