a b s t r a c tThis research investigates high pressure diesel fuel injection into the combustion chamber by performing computational simulations using the Euler-Eulerian multiphase approach. Six diesel-like conditions were simulated for which the liquid fuel jet was injected into a pressurised inert environment (100% N 2 ) through a 205 lm nozzle hole. The analysis was focused on the liquid jet and vapour penetration, describing spatial and temporal spray evolution. For this purpose, an Eulerian multiphase model was implemented, variations of the sub-model coefficients were performed, and their impact on the spray formation was investigated. The final set of sub-model coefficients was applied to all operating points. Several simulations of high pressure diesel injections (50, 80, and 120 MPa) combined with different chamber pressures (5.4 and 7.2 MPa) were carried out and results were compared to the experimental data. The predicted results share a similar spray cloud shape for all conditions with the different vapour and liquid penetration length. The liquid penetration is shortened with the increase in chamber pressure, whilst the vapour penetration is more pronounced by elevating the injection pressure. Finally, the results showed good agreement when compared to the measured data, and yielded the correct trends for both the liquid and vapour penetrations under different operating conditions.

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This research deals with computational modelling of non-reactive and reactive turbulent spray processes. The spray process is modelled using the Euler Eulerian multiphase approach together with a size-of-classes model where the discrete phase is considered as continuum and divided into sub-classes. The combustion process is modelled by taking into account chemical kinetics and solving homogeneous gas phase reactions. The combustion model is implemented into a commercial computational fluid dynamics code, and used in combination with previously validated spray sub-models. Several non-reactive cases are modelled by comparing the fuel spatial and temporal development to the available experimental data. The modelled results show excellent agreement for fuel penetration and mixture distributions. Furthermore, the developed method is validated by modelling reactive spray processes within constant volume vessel, and by comparing results to the Engine combustion network experimental data. The vessel conditions correspond well to diesel-like conditions in terms of gas residuals, pressure and temperature. Finally, the given results show a good agreement for the lift-off length and the ignition delay trends compared to the experimental data, but a slight discrepancy in the combustion process occurrence is observed.

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To explore the influence of fuel injection strategy on the combustion process, the Computational Fluid Dynamics (CFD) simulations were performed, and simulation results were validated against the experimental data measured at different rail pressures and injection timings. The experiments were conducted on a diesel engine equipped with an advanced injection system that allows full control over the injection parameters. To model the combustion process of EN590 diesel fuel, two different approaches were used: the General Gas Phase Reactions (GGPR) approach and the 3-zones Extended Coherent Flame Model (ECFM-3Z+). The calculated results, such as mean pressure and rate of heat release, were validated against experimental data in operating points with different injection parameters in order to prove the validity of spray and combustion sub-models. At the higher injected pressure, GGPR model showed better prediction capability in the premixed phase of combustion process, compared to the ECFM-3Z+ model. Nevertheless, in the rate-controlled phase of combustion process, ECFM-3Z+ model shows stronger diffusion of temperature field, due to the more detailed consideration of combustion diffusion phenomena in the ECFM-3Z+ governing equations. Furthermore, the results show that the rail pressure has a lower impact on the combustion process for injection timing after the Top Dead Centre (TDC). Both, single and multi-injection cases are found to be in a good agreement with the experimental data, while the GGPR approach was found to be suitable only for combustion delay determination and ECFM-3Z+ also for the entire combustion process.

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