The phenomenon of the motor oil viscosity stratification in lubricating the cylinder-piston units of marine diesel engines has been investigated. The correlations for determining the shear stress and the velocity, occurring in the liquid flow between the parallel planes, have been given. The modes of the hydrodynamic and the boundary lubrication, taking place in the cylinder assembly of the marine diesel engine operation, have been considered. The methodology has been introduced for determining the viscosity of the boundary layer, which separates the surfaces of the piston ring and that of the cylinder bushing in the marine diesel motor operation. The results of the experiments, confirming the presence of the viscosity stratification in the boundary lubrication layer of the marine motor oil, have been submitted.

Abstract:The possibility of marine slow-speed diesel engine cylinderpiston group diagnosis with view to the specification of waste oil taken from the under-piston space has been discussed. The specifics of using high-base cylinder oils in marine slow-speed diesel engines to prevent sulfur corrosion of the cylinders have been described. Typical challenges, arising in the process of using oils for lubricating the cylinder-piston group and ways to overcome such challenges have been specified. Empirical data that allowed for determining the optimum cylinder oil consumption and ensuring minimum wear diesel engine cylinder bushings have been provided. The experiments that were carried out in sea ship conditions are proved by findings of an oil analysis at a third-party onshore research laboratory.