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Coupled Experimental and Numerical Investigation of Reactive Spray Processes in Internal Combustion Engine

It is known that the injection strategy in the internal combustion engines has an impact on the combustion, pollutant formation and total energy efficiency. In the modern internal combustion engines, the multi-injection strategies are commonly used to reduce pollutant emissions and combustion noise. Furthermore, the combustion process as a result of the multi-injection strategy depends on numerous parameters that are commonly examined with the coupled Computational Fluid Dynamics (CFD) and experimental investigation. In the observed experimental direct injection diesel engine, the liquid fuel is injected through the separated pilot and main injections. The pilot injection is used to produce a small amount of vapour that ignites and increases the mean in-cylinder temperature before the main injection occurs. The special focus of this research is given to the numerical investigation of the spray influence on the combustion process, where two spray modelling approaches were applied. The Euler Lagrangian (EL) spray approach and the Euler Eulerian (EE) spray approach were investigated and compared with the experimental results. In both spray modelling approaches, the general gas phase reactions were used for describing the combustion process. The 3D results show that the evaporated fuel predicted with the EE approach has a better physical description in the dense spray region than with the conventional EL modelling approach that has the better physical description in the near wall region. Additionally, the difference between spray models in the fuel disintegration and evaporation process modelling resulted in the lower temperature values of the gas phase in the near the nozzle region for the EE spray approach. Finally, the results from both spray modelling approaches, such as the mean pressure and rate of heat release are found to be in good agreement with the experimental results.

Spray, Diesel engine, Multi-injection strategy, Combustion

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