2302 ディーゼル機関内混合制御によるNOx低減のための効果解析(S25 エンジンの排気浄化・後処理,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

概要

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Experiment and numerical simulation indicated that the large NOx formation in diesel engine is due to the weak mixing intensity in the spray tip region, where the flow and turbulence structure is quite different from the continuous jet flames. The fact indicates that there is a possibility of reducing NOx from diesel engines by enhancing mixing intensity at the spray tip region to the level of continuous jet flame. This paper presents the analysis of NOx formation in diesel engines using HTB-DECS to confirm the effect of pre-shock jet. This analysis performed by changing the magnitude and/or timing of the turbulence that influences the air entrainment into the fuel-spray. The results show that NOx formation is greatly related in the turbulence strength. It is very important to control the timing to give the strong turbulence. Furthermore, the simulation also performed by the jet flame with/without the impinging jet using FLUENT. The large NOx reduction was able to be confirmed in the case with the impinging jet.
2008-08-02