Computational Investigation of the Effects of Injection Strategy and Rail Pressure on Isobaric Combustion in an Optical Compression Ignition Engine
Paper in proceeding, 2021

The high-pressure isobaric combustion has been proposed as the most suitable combustion mode for the double compre4ssion expansion engine (DCEE) concept. Previous experimental and simulation studies have demonstrated an improved efficiency compared to the conventional diesel combustion (CDC) engine. In the current study, isobaric combustion was achieved using a single injector with multiple injections. Since this concept involves complex phenomena such as spray to spray interactions, the computational models were extensively validated against the optical engine experiment data, to ensure high-fidelity simulations. The considered optical diagnostic techniques are Mie-scattering, fuel tracer planar laser-induced fluorescence (PLIF), and natural flame luminosity imaging. Overall, a good agreement between the numerical and experimental results was obtained. Upon validation, the optimized models have been used to conduct a comparative study between the conventional diesel combustion (CDC) and the isobaric combustion cases with different pressure levels, in terms of engine performance and emissions. Compared to the CDC case, the isobaric combustion cases led to a lower NOx emission but higher sooting tendency due to the increased diffusion combustion feature, although most of the soot was oxidized in the later engine cycle. To further reduce soot emission, the effects of various rail pressures and injector holes number were evaluated. The results indicated that the higher injection pressure was more effective in soot reduction for the isobaric combustion case but it deteriorated the thermal efficiency. It was also found that increasing the number of injector holes from the reference six to ten led to the lowest soot emission without significantly affecting the efficiency.

Optical data processing






Hammam Aljabri

King Abdullah University of Science and Technology (KAUST)

Xinlei Liu

King Abdullah University of Science and Technology (KAUST)

Moaz Allehaibi

King Abdullah and Umm Al-Qura Universities

Abdullah S. Alramadan

Saudi Arabian Oil Company (Saudi Aramco)

Jihad Badra

Saudi Arabian Oil Company (Saudi Aramco)

Moez Ben Houidi

King Abdullah University of Science and Technology (KAUST)

Bengt Johansson

Chalmers, Mechanics and Maritime Sciences (M2), Combustion and Propulsion Systems

Hong G. Im

King Abdullah University of Science and Technology (KAUST)

SAE Technical Papers

01487191 (ISSN) 26883627 (eISSN)


SAE 15th International Conference on Engines and Vehicles, ICE 2021
Capri, Italy,

Subject Categories

Other Mechanical Engineering

Energy Engineering

Atom and Molecular Physics and Optics



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