Numerical study of the scavenging process in a large two-stroke marine engine using RANS and LES turbulence models Technical University of Denmark

Format:

Book

Conference/Event

Author/Creator:

Nemati, Arash, author.

Contributor:

Jensen, Michael Vincent

Mayer PhD, Stefan

Ong, Jiun Cai

Pang, Kar Mun

Walther, Jens Honore

Conference Name:

SAE Powertrains, Fuels & Lubricants Meeting (2020-09-22 : Krakow, Poland)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2020

Summary:

The scavenging process in a large two-stroke marine diesel engine is studied in this paper using computational fluid dynamics (CFD) simulation. The scavenging process is one of the most important parts of the two-stroke marine engines which has a direct effect on fuel economy and emissions. This process which establishes the initial conditions for combustion is responsible for fresh air delivery, removing the combustion products from the cylinder, cooling the combustion chamber surfaces and providing a swirling flow for better air-fuel mixing. Therefore, having a better understanding of the process and flow pattern during it is crucial. This understanding is not achievable by experimental tests for large engines during engine operation due to the difficulties of measuring the flow field inside the cylinder. In this study, the axial and tangential velocities were compared and validated with the experimental results obtained from Particle Image Velocimetry (PIV) tests using Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) turbulence models. There is a good agreement between the numerical and experimental results. Then, the flow inside the cylinder is studied in four different locations related to the bottom of scavenging ports during the exhaust valve opening time. The replacement of combustion products with fresh air is studied. Then the flow in the ports is investigated by calculation of effective flow angle and mass flow rate from the portraits Results show a mass flow rate is different for various ports related to their position inside the scavenging box. Also, the effective flow angle for the ports is different from the geometrical angle of ports (20). Results illustrate better performance of LES in the prediction of the flow field, especially in the prediction of the tangential velocity which is crucial for the prediction of an accurate swirl and air-fuel mixing inside the marine engines

Notes:

Vendor supplied data

Publisher Number:

2020-01-2012

Access Restriction:

Restricted for use by site license