Numerical Study of Diesel Combustion Processes by the Combined CMC Combustion and KH-RT Breakup Models
- Numerical Study of Diesel Combustion Processes by the Combined CMC Combustion and KH-RT Breakup Models
- Wang Zhaoxin
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- Numerical study is performed for the combustion processes in a direct-injection diesel engine by a modified version of the KIVA-3V code. The results contribute to the development of a predictive model based on the KIVA-3V code for direct-injection engine combustion. In this study numerical modeling and validation are performed to resolve some important spray features. The KH-RT model is implemented to simulate spray breakup in a diesel engine. The results are validated against the PDPA measurement data for sprays in a constant volume chamber. The KH-RT model is combined with the CMC turbulent combustion model in the KIVA-3V code.
The spray combustion processes have been successfully simulated for conventional diesel engine conditions. The cylinder is modeled as an ISR with the spatially integrated CMC equations involving multiple flame groups of sequentially evaporated fuel. It is shown that the current numerical methods are capable of reproducing the proper qualitative trend for combustion processes in conventional diesel engines. Furthermore, a new diesel combustion mode of pHCCI is tested with the modified CMC model. The lean flammability limit is applied to consider extinction of lean mixture of pilot injertion fuel. The deviation due to a rapid pressure rise after ignition is attributed to simultaneous burning of combustible mixture and absence of any flame propagation in the CMC model. Further research may be required to study premixed flame propagation, wall film models and ignition model, which play a significant role in heat release of pHCCI engines.
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