Lubricant Transport across Piston Rings in Large Two-Stroke Diesel Engines - Theory and Experiments

Hannibal Toxværd Overgaard

Research output: Book/ReportPh.D. thesisResearch

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Abstract

Lubricant Transport across Piston Rings in Large Two-Stroke Diesel Engines - Theory and Experiments.
A study of the lubricant transport across the piston rings in large two-stroke marine diesel engines is presented.
Cylinder lubrication systems for large two-stroke marine diesel engines do not support recirculation of the lubricant and it is lost after usage. The lu-bricant is expensive and may contain several polluting additives. Reducing the lubricant consumption is economically profitable and reduces emissions. The physical mechanisms of lubricant transport across piston rings are investigated and presented in this work.
The structure of the numerical model is described. The work covers solving Reynolds equation by the finite difference method, force equilibrium of the piston ring by considering the lubricant stiffness, transient mass conservation as well as the influence from rough surfaces in the hydrodynamic effects and asperity contact.
Theoretical investigations of the influence by piston ring curvatures for fully flooded and starved conditions as well as different lubricant profiles on the liner are conducted. Results are presented for the lubricant consumption and asperity contact friction as functions of lubricant injection positions on the liner, piston ring asymmetries and curvatures.
The knowledge gained in the mechanisms controlling the lubricant consump-tion can be utilized for optimizing the cylinder lubricant injection system for reduced consumption and asperity contact friction between the surfaces.
The method of laser induced fluorescence is presented and applied in a re-ciprocating test rig. It mimics the lubrication conditions between a piston ring and cylinder liner. Results for friction forces and minimum film thicknesses are presented.

Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages182
ISBN (Electronic)978-87-7475-540-1
Publication statusPublished - 2018
SeriesDCAMM Special Report
NumberS250
ISSN0903-1685

Keywords

  • Rribology
  • Lubrication
  • Reynolds equation
  • Piston rings
  • Diesel engines
  • Lubricant transport
  • Experiments
  • Fnite difference method
  • Laser induced fluorescence

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