An improved Representative Interactive Flamelet model accounting for evaporation effect in reaction space (RIF-ER)

Recently, applications of spray combustion in internal combustion engines (ICE) are being expanded from conventional to gasoline direct injection engines. Moreover, stratification using spray is further considered as a controlled autoignition (CAI) measure in Homogeneous Charge Compression Ignition (HCCI) engines.;A well validated spray combustion model can provide a good modeling tool which can facilitate understanding of spray combustion physics. In this research, a spray combustion model is proposed to model low temperature combustion in internal combustion engines. The proposed model is based on the Representative Interactive Flamelet (RIF) model of Peters (2000). In addition to the original RIF model, the effect of spray and vaporization of droplets in the reaction space were considered to be included in the governing equations as source terms. The effect of such source terms were examined in the reaction space in idealized control volumes, where the effect of vaporization is assumed as gaseous fuel addition with known rate of addition. It was found that the effect of spray may not be negligible when fuel addition occurs over a reaction space with chemical reaction. The proposed model was validated by comparing pressure and fuel concentration against experimental data from the rapid compression machine experiment of Akiyama et al. (1998) and the diesel engine experiment of Hong et al. (2008). Predictions showed good agreement with the experimental observations. Comparison between numerical models, one with spray source terms and the other without them has been carried out to examine the effect of spray source terms on spatial fuel distributions and overall pressure histories.;The proposed model has been implemented in KIVA3v. The proposed model is applied to investigate the effect of stratification under PPCI operating condition using direct injection. An experimental study on the effect of stratification on combustion and emission has been numerically reproduced. The numerical results showed good qualitative agreement with the measured engine performance and emission trend against the experimental data. Detailed analysis of the in-cylinder combustion is also provided.