불균일한 온도 및 화학구성을 지닌 정상헵탄/공기 혼합물의 점화에 미치는 NTC영역의 효과

Abstract

The effect of the negative temperature coefficient (NTC) on the ignition of a stratified lean n-heptane/air mixture of temperature and equivalence ratio was investigated using 2-D direct numerical simulations (DNSs) with a 58-species reduced mechanism. It was found that for � � in the NTC regime, fuel stratification is more effective than thermal stratification in controlling the ignition delay and mitigating the heat release rate (HRR). One of the key finding in this study is that for the intermediate � � , the overall combustion becomes more advanced and mean heat release rate (HRR) is temporally more distributed with increasing �′ regardless of the negatively-correlated � � � relations. It is primarily because the deflagrative mode prevails at the reaction fronts for large �′ and hence the combustion occurs subsequently, rendering mean HRR more distributed over time.