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CFD analysis of the marine engine MAN 7S50MC

The MC series of the two-stroke MAN B&W Diesel were introduced in the early 80s of last century. Its main application is the propulsion of all types of vessels, medium and large sizes. These engines have also been used in terrestrial applications, mainly for production of electrical power.


An advantage of the MAN B&W MC series is that they incorporate the uniflow scavenging, much more efficient than the former competitors, such as Sulzer RND, MAN KSZ, among others, who employ loop or cross scavenging. 

Two-stroke engines generally have a drawback which has a great influence on the development of its operating cycle. This problem is motivated by the neccesity of the four phases of the operating cycle (expansion, exhaust, intake and compression ) in a single turn of the crankshaft, therefore the periods required for each of the phases are necessarily shorter than a four-stroke engine. Between them, the most critical stages are exhaust-intake, when the charge in the cylinder is renewed. For this reason, the design of the engine is extremely important.

The process of displacement the flue gases out of the cylinder, and filling with fresh air charge, called "scavenging", has a decisive influence on fuel consumption, power and pollution. 

 The following figure shows the airflow (red) and exhaust gas (blue) inside one of the cylinders.

As can be seen in the previous figure, incoming air is used to blow out or exhaust gas sweep and meanwhile filling the space with fresh air. 

The following figure was obtained through a CFD analysis. It shows the velocity distribution of the flow in the cylinder during the renovation of the load.

The following figure shows the mass fractions exhaust (blue) and air (red) for a tour from 90° to 270° crank angle.

In this CFD analysis, the free software OpenFOAM was employed. The reason is that this is an open source and thus it allows a complete manipulation of the governing equations. This is essential to carry out this type of analysis. It is necessary to adjust several parameters and some of them cannot be modified with other commercial softwares.

To read more about the realization of a CFD study of the scanning system of a type of two slow times we encourage you to read the article " Computational Fluid Dynamics Analysis of theScavenging Process in the MAN B & W 7S50MC Two-Stroke Marine Diesel Engine " published in journal of Ship Research, one of the publications with the highest impact factor in the world in its sector, with a type a classification according to the basis of JCR (journal Citation Reports) data.


imagencursoCFD with OpenFOAM online course


[5Grupo de Innovaciones Mariñas de la Universidad de La Coruña
Published 2016-02-12 15:30:35 by Carlos Rodriguez & Isabel Lamas


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