Effects of Multiple Injectors on Spray Characteristics and Efficiency in Internal Combustion Engines

Abstract
High-pressure internal combustion engines promise high efficiency, but a proper injection strategy to minimize heat losses and pollutant emissions remain a challenge. Previous studies have concluded that two injectors, placed at the piston bowl's rim, simultaneously improve the mixing and reduce the heat losses. The two-injector configuration further improves air utilization while keeping hot zones away from the cylinder walls. This study investigates how the two-injector concept delivers even higher efficiency by providing additional control of spray -and injection angles. Three-dimensional Reynolds-averaged Navier-Stokes simulations examined several umbrella angles, spray-to-spray angles, and injection orientations by comparing the two-injector cases with a reference one-injector case. The study focused on heat transfer reduction, where the two-injector approach reduces the heat transfer losses by up to 14.3 % compared to the reference case. Finally, this study connected the two-injector approach to a waste-heat recovery system through GT-Power 1-D simulations, increasing the importance of heat transfer reduction. The final two-injector system then delivered a 54.4% brake thermal efficiency compared to 53% of the one-injector reference case.

Citation
Ávila Jiménez, C. D., Nyrenstedt, G., Goyal, H., Andersson, A., Im, H. G., & Johansson, B. (2021). Effects of Multiple Injectors on Spray Characteristics and Efficiency in Internal Combustion Engines. SAE Technical Paper Series. doi:10.4271/2021-01-0501

Acknowledgements
This work was sponsored by King Abdullah University of Science and Technology (KAUST) and supported by the KAUST Supercomputing Laboratory (KSL). All simulations were performed on KSL's Shaheen-II supercomputer using CONVERGE CFD software. Convergent Science provided CONVERGE licenses and technical support for this work.

Publisher
SAE International

Conference/Event Name
SAE 2021 WCX Digital Summit

DOI
10.4271/2021-01-0501

Additional Links
https://www.sae.org/content/2021-01-0501/

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