0

Full Content is available to subscribers

Subscribe/Learn More  >

Parametric Study of the Scavenging Process in Marine Two-Stroke Diesel Engines

[+] Author Affiliations
Fredrik Herland Andersen

MAN Diesel & Turbo SE, Copenhagen, DenmarkTechnical University of Denmark, Kgs. Lyngby, Denmark

Stefan Mayer

MAN Diesel & Turbo SE, Copenhagen, Denmark

Paper No. ICEF2015-1075, pp. V001T01A004; 9 pages
doi:10.1115/ICEF2015-1075
From:
  • ASME 2015 Internal Combustion Engine Division Fall Technical Conference
  • Volume 1: Large Bore Engines; Fuels; Advanced Combustion
  • Houston, Texas, USA, November 8–11, 2015
  • Conference Sponsors: Internal Combustion Engine Division
  • ISBN: 978-0-7918-5727-4
  • Copyright © 2015 by ASME

abstract

Large commercial ships such as container vessels and bulk carriers are propelled by low-speed, uniflow scavenged two-stroke diesel engines. The integral in-cylinder process in this type of engine is the scavenging process, where the burned gas from the combustion process is evacuated through the exhaust valve and replaced with fresh air for the subsequent compression stroke. The scavenging air enters the cylinder via inlet ports which are uncovered by the piston at bottom dead center (BDC). The exhaust gas is then displaced by the fresh air. The scavenging ports are angled to introduce a swirling component to the flow. The in-cylinder swirl is beneficial for air-fuel mixture, cooling of the cylinder liner and minimizing dead zones where pockets of exhaust gas are trapped. However, a known characteristic of swirling flows is an adverse pressure gradient in the center of the flow, which might lead to a local deficit in axial velocity and the formation of central recirculation zones, known as vortex breakdown. This paper will present a CFD analysis of the scavenging process in a MAN B&W two-stroke diesel engine. The study include a parameter sweep where the operating conditions such as air amount, port timing and scavenging pressure are varied. The CFD model comprise the full geometry from scavenge receiver to exhaust receiver. Asymmetric inlet and outlet conditions is included as well as the dynamics of a moving piston and valve. Time resolved boundary conditions corresponding to measurements from an operating, full scale production, engine as well as realistic initial conditions are used in the simulations. The CFD model provides a detailed description of the in-cylinder flow from exhaust valve opening (EVO) to exhaust valve closing (EVC). The study reveals a close coupling between the volume flow (delivery ratio) and the in-cylinder bulk purity of air which appears to be independent of operating conditions, rpm, scavenge air pressure, BMEP etc. The bulk purity of air in the cylinder shows good agreement with a simple theoretical perfect displacement model.

Copyright © 2015 by ASME
Topics: Diesel engines

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In