An investigation of combustion robustness of HCCI engines at retarded combustion phasing operation (by use of numerical analysis with multi zone model)

The purpose of this study is to investigate combustion robustness of HCCI engines at retarded combustion phasing operation by going through numerical analysis with multi-zone model. The reason of calculation with the multi-zone model is to examine the mechanism of combustion phasing retard to reduce an excessive pressure-rise rate and keep combustion robustness with thermal stratification. It is found that excessive combustion phasing retard causes cyclic dispersion and misfire. With thermal stratification, combustion robustness at retarded combustion phasing operation is analyzed. As a result, in case of same initial mass averaged gas temperature as larger thermal stratification was set, 50% heat release timing of high temperature heat release (HTHR) was advanced because higher initial gas temperature zone was auto-ignited in turn. It was confirmed to trade off between pressure-rise rate and 50% heat release timing in HTHR.