Application Of Impingement Nozzle And Pilot To Diesel Premixed Charge Compression Ignition Combustion

To meet the requirement of energy crisis and stringent exhaust emission legislations, more emphasis are laid on how to reduce both fuel consumption and emissions. However, characteristics of conventional DI diesel engine combustion determine the compromise between fuel conversion efficiency improvement and harmful emission control, ad well as the tradeoff between NOx and PM emissions control. Therefore, DI diesel engine development is extremely difficult due to this reason. To solve this problem, the conventional DI diesel engine combustion must be renovated. As a new kind of combustion, Homogeneous Charge Compression Ignition (HCCI) combustion can decrease NOx and PM emission simultaneously and maintain high fuel conversion efficiency close to direct injection diesel engine. With these two advantages, HCCI combustion is becoming one of the most promising technologies in IC engine field.Based on the research of conventional diesel combustion and the analysis of diesel HCCI combustion, Split injection is proposed by using impingement nozzle and two injection pumps. This novel combustion process is investigated in a single cylinder diesel bench on 1135 type single cylinder test engine.To realize two aims mentioned above, this paper utilizes two fuel injection pumps to finish stage split injection on the basis of the original injection sets of the 1135 diesel engine. According the simulating calculation, appropriate fuel injection advance angle and the fuel quality of pilot injection were selected to finish the all-nature pre-mixing combustion of the diesel on the testing machine. The experiment indicates that, because the thin pre-mixing gas can be formed in the pre-injection stages, the fuel pilot injection can shorten the ignition delay period of the main injection, hasten the combustion speed, avoid the sudden rise of the pressure and the temperature in diesel's initial combustion stage, reduce the burst pressure and the rate of fuel consumption of the diesel, especially reduce the emission rate of NOx. Since the impingement nozzle is adopted, the momentum lose of the fuel spray is rather large. This results in the short spray penetration and the low combustion speed. Consequently, the emission of particulate matters (PM) is relatively higher than before.