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Numerical simulation on effects of spray angle in a swirl chamber combustion system of DI (direct injection) diesel engines
- Wei, Shengli, Ji, Kunpeng, Leng, Xianyin, Wang, Feihu, Liu, Xin
- Energy 2014 v.75 pp. 289-294
- air, combustion, combustion efficiency, diesel engines, emissions, fuels, mathematical models, nitric oxide, soot, temperature
- In order to make better air utilization in combustion chamber to improve the mixture quality, enhance combustion efficiency and reduce emissions, a new swirl chamber combustion system of DI (direct injection) diesel engines is proposed. The in-cylinder spray, mixture formation and combustion progresses are simulated and investigated at different nozzle angles with AVL-FIRE code. Results show that in the current combustion system, spray angle of 146° is the best on the aspect of mixture homogeneity among all the cases. NO mass fraction is the lowest at spray angle of 154°, while Soot mass fraction is the lowest at spray angle of 146°. At the initial stage of spray, the fuel/air equivalence ratio distribution was primarily controlled by the squish and swirl, while after ignition in expansion stroke, the combustion swirl and reverse squish had great impact on the in-cylinder temperature distribution. To sum up, the spray angle and air motion matching with the combustion chamber is a key factor on combustion process and emissions performance. Considering the emission performance, spray angle of 150° is a relatively better compromise in the new combustion system.