A detailed chemical kinetics model was used in a computational fluid dynamics (CFD) code to study the combustion process of a homogeneous charge compression ignition (HCCI) engine fuelled with isooctane. The detailed chemical kinetics code CHEMKIN was implemented into the multi-dimensional CFD code KIVA-3V so that the chemical reactions and in-cylinder flow were coupled. The results indicate that the grid density and time step have little influence on the accuracy of the computational analysis of the HCCI combustion process; however, the initial temperature of the charge influences the burn point greatly. A comparative study on submodels indicates that the results calculated by the renormalization group k-ε turbulence model, the Han-Reitz heat transfer model, and the crevice flow model agree better with measurements than their counterparts, the standard k-ε turbulence model, the traditional heat transfer model, and the non-crevice flow model respectively. The modified multi-dimensional model predicts with good accuracy the pressure, heat release rate, and emissions under different equivalence ratios. The benefits and limits of four approaches extending the operation range of HCCI engines to higher load, i.e. retarded burn point by decreasing the intake temperature, enhanced thermal stratification by lowering the cylinder wall temperature and increasing the swirl ratio, and increasing the exhaust gas recirculation (EGR) ratio, were analysed by this model. The results indicate that proper combustion phasing retardation can reduce the ringing intensity significantly and maintain the performance and emissions level. Among these four methods, increasing the swirl ratio could reduce the ringing intensity most significantly, while EGR shows an excellent performance in all aspects.
Numerical simulation of homogeneous charge compression ignition combustion using a multi-dimensional model
2007-04-01
16 pages
Article (Journal)
Electronic Resource
English
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