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Article

CFD Analysis of a Large Marine Engine Scavenging Process

Faculty of Engineering, University of Rijeka, Vukovarska 58, 51000 Rijeka, Croatia
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Author to whom correspondence should be addressed.
Academic Editor: Li Xi
Processes 2022, 10(1), 141; https://doi.org/10.3390/pr10010141
Received: 26 August 2021 / Revised: 29 December 2021 / Accepted: 7 January 2022 / Published: 10 January 2022
(This article belongs to the Special Issue Enhancement of Heat Transfer and Fluid Flow)
The scavenging process is an important part of the two-stroke engine operation. Its efficiency affects the global engine performance such as power, fuel consumption, and pollutant emissions. Slow speed marine diesel engines are uniflow scavenged, which implies inlet scavenging ports on the bottom of the liner and an exhaust valve on the top of the cylinder. A CFD model of such an engine process was developed with the OpenFOAM software tools. A 12-degree sector of the mesh was used corresponding to one of the 30 scavenging ports. A mesh sensitivity test was performed, and the cylinder pressure was compared to experimental data for the analyzed part of the process. The scavenging performances were analyzed for real operation parameters. The influence of the scavenge air pressure and inlet ports geometric orientation was analyzed. The scavenging process is analyzed by means of a passive scalar representing fresh air in the cylinder. Isosurfaces that show the concentration of fresh air were presented. The variation of oxygen and carbon dioxide with time and the axial and angular momentum in the cylinder were calculated. Finally, the scavenging performance for the various operation parameters was evaluated by means of scavenging efficiency, charging efficiency, trapping efficiency, and delivery ratio. It was found that the scavenging efficiency decreases with the engine load due to the shorter time for the process. The scavenging efficiency increases with the pressure difference between the exhaust and scavenging port, and the scavenging efficiency decreases with the increase in the angle of the scavenging ports. It was concluded that smaller angles than the industry standard of 20° could be beneficial to the scavenging efficiency. In the investigation, the charging efficiency ranged from 0.91 to over 0.99, the trapping efficiency ranged from 0.54 to 0.83, the charging efficiency ranged from 0.78 to 0.92, and the delivery ratio ranged from 1.21 to 2.03. View Full-Text
Keywords: CFD simulation; large marine engine; scavenging process; sector mesh CFD simulation; large marine engine; scavenging process; sector mesh
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MDPI and ACS Style

Senčić, T.; Mrzljak, V.; Medica-Viola, V.; Wolf, I. CFD Analysis of a Large Marine Engine Scavenging Process. Processes 2022, 10, 141. https://doi.org/10.3390/pr10010141

AMA Style

Senčić T, Mrzljak V, Medica-Viola V, Wolf I. CFD Analysis of a Large Marine Engine Scavenging Process. Processes. 2022; 10(1):141. https://doi.org/10.3390/pr10010141

Chicago/Turabian Style

Senčić, Tomislav, Vedran Mrzljak, Vedran Medica-Viola, and Igor Wolf. 2022. "CFD Analysis of a Large Marine Engine Scavenging Process" Processes 10, no. 1: 141. https://doi.org/10.3390/pr10010141

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