Mathematical modelling of mixture formation in the combustion chamber of a diesel engine
DOI:
https://doi.org/10.15587/2706-5448.2025.326746Keywords:
droplet movement, evaporation, mixture formation, spray dispersion, volumetric combustion, excess air, steam unevennessAbstract
The object of research is the process of fuel mixture formation in a vortex combustion chamber located in the piston of a diesel engine.
Ineffective mixture formation leads to increased specific fuel consumption and harmful emissions into the atmosphere. The research addresses determining the conditions under which complete evaporation of droplets is achieved and the required ratio of the amount of fuel vapor and the available amount of air depending on the piston radius.
A mathematical model was created to describe the behavior of fuel droplets under the influence of aerodynamic forces, heat transfer, and phase transition processes. The calculations determined the radial fuel vapor concentration and air-fuel ratio distribution. The study found that fuel droplets with sizes ranging to 90.7 µm are completely evaporated which contributes to volumetric mixture formation. The model also identified regions where the mixture reaches stoichiometric conditions necessary for autoignition, particularly at a radius of r/Rc=0.22.
This is explained by the rapid evaporation of small droplets, the number of which, as a function of the diameter distribution, is the majority, and their high speeds of movement relative to air and high mass transfer coefficients in the initial spraying area.
The study demonstrates that despite non-uniform fuel vapor distribution, volumetric mixture formation is achieved. The interaction between fuel droplets and the swirling air motion ensures adequate mixing, facilitating complete and efficient fuel combustion.
The results can be applied to optimize diesel engine designs by improving combustion chamber geometry and fuel injection strategies. The model is particularly useful for engines with high-pressure fuel injection systems. The work results contribute to developing more efficient diesel engines that comply with stricter emission regulations.
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Copyright (c) 2025 Oleksandr Zhevzhyk, Iryna Potapchuk, Vadym Horiachkin, Serhii Raksha, Dmytro Bosyi, Andrii Reznyk
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