Investigation of the piston running properties of large 2-stroke marine diesel engines and analysis of future lubricant concepts

Background

In international shipping, large 2-stroke marine engines are the dominant source of propulsion. Future emission regulations as well as potential future fuels for decarbonization place high demands on optimized tribological systems as well as on future lubrication strategies. These strategies need to be aligned with potential fuel types to reliably provide operational excellence.

Fig.1: Schematic of an investigated tribological system of a large two stroke marine diesel engine.

Objectives

Understanding the tribological and rheological behavior based on engine operating conditions, provides the possibility to redefine lubrication strategies towards lowest possible oil consumption and at the same time most reliable operating conditions. The method of ultrasonic reflectometry is deployed to determine the lubricant film thickness at the cylinder liner – piston ring interface during engine operation.

Results

Lubricant film thickness (OFT) is determined using a novel approach of ultrasound reflectometry. Detailed investigations with WinGD and a close cooperation with the University of Sheffield leads to a new method of a crank angle resolved determination of OFT during engine operation, which leads to a much better understanding of tribological and rheological effects at the cylinder liner – piston ring interface. Elaborated results provide the basis for the development of a detailed simulation model to support the development of future lubrication strategies.

Fig.2: Methodology to obtain dynamic oil film thickness information in a fired engine.