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Simulation of Spray Formation and Mixing in Diesel Engines with Novel Injector Designs

Ashrafi Nik, M; (2013) Simulation of Spray Formation and Mixing in Diesel Engines with Novel Injector Designs. Masters thesis (M.Phil), UCL (University College London). Green open access

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Abstract

Improvement of the Diesel engine and optimization of the combustion process continues to be an important aspect in the efforts to meet new emissions regulations. The most important factors which directly influence the performance of the Diesel engine are related to the spray formation and vaporization of the liquid fuel upon injection into the cylinder. Therefore, in order to improve Diesel engines new studies need to be undertaken to further develop the injection system and, in particular, the nozzle layout and subsequent spray formation. This thesis describes the computational modelling of spray formation and atomization for a novel type of Diesel injector with a new nozzle layout that consists of a group of upper and lower sets of holes. The KIVA-3V code with extended capability of Large Eddy Simulation (LES) was utilized for this work. This particular version of KIVA can predict two-phase flows where the fluid dynamics behaviour of an annular fuel jet and the effects of the initial ambient swirl on the flow field need to be captured. The original code did not support the modelling of two-row injectors with different velocity profiles, hence certain modifications were implemented. The developed version of KIVA is capable of simulating two or more rows with different input parameters such as velocity, angle of injection and injection pressure. It also includes a new formulation for modelling the collisions processes of liquid droplets based on initial droplet diameter ratio, Weber number and impact parameter. The yielded results were post-processed and validated against experimental data in terms of penetration length for the vapour and liquid phases of the fuel and spray curvature. Significant improvement was observed in comparison to predictions obtained with the previous version of the code and good agreement was obtained with experimental data.

Type: Thesis (Masters)
Qualification: M.Phil
Title: Simulation of Spray Formation and Mixing in Diesel Engines with Novel Injector Designs
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1386648
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