Analysis of spray to spray interaction and smoke emission for diesel multiple injections and quick rising injection rate 2019-01-2272
Diesel engines have smoke trade-offs with both NOx and combustion noise. Both the increment of air entrainment into the spray and deceleration of heat release rate slope which become quickly thanks to the increase of air entrainment are effective for overcoming the trade-off between smoke emission and combustion noise.
In this study, effect of quick rising injection rate and pre-injection was focused as an enabler for the both. The mechanism of improvement in the trade-off caused by the quick rising injection rate and pre-injection was clarified by analyzing characteristics of spray and combustion, interaction of pre-injected spray to main-injected spray and behavior of smoke emission. Some visualization techniques were adapted to analysis of sprays and combustions. Spray momentum measurement was used for the air entrainment and mixture formation process analyzation. The spray drops and smoke were visualized simultaneously with laser extinction method to analyze the spray to spray interaction and smoke emission.
As a result, quick rising injection rate contribute to smoke reduction by increasing set-off length and amount of entrained air. Pre-injection carried out just before the main-injection cause interaction with main-injection in the region, where the air entrainment near the nozzle was restricted due to the effects of sprays from neighboring holes, and contribute to reduction of combustion noise without increase of smoke.
Citation: Yamashita, H., Tomomatsu, K., Toda, N., Shimode, K. et al., "Analysis of spray to spray interaction and smoke emission for diesel multiple injections and quick rising injection rate," SAE Technical Paper 2019-01-2272, 2019. Download Citation