Research of the oils for ship engine by means of dynamic light scattering method

The possibility of using the photon correlation spectroscopy method for the purpose of diagnostics of marine engines based on used engine oil to improve the efficiency and safety of operation of marine vessels is investigated in this article. The need to develop and implement new effective methods of diagnostics of marine diesel engines is an actual task. The purpose of this work was to study a number of fresh and used oils by dynamic light scattering method to determine the changes that occur with the oil during the operation of a marine diesel engine, and to find out the connection of these changes with engine failures. There are no publications about such studies in the literature, and the results presented in this paper are new. The photon correlation spectroscopy method was used to measure correlation functions and then obtain distributions of correlation times, diffusion coefficients, and particle sizes. To invert the Laplace transform, we used a method based on minimizing the standard deviation and regularization (RILT), modified to find the correlation time distribution. It was found that the distributions of hydrodynamic radii of particles for fresh and used oils differ significantly. By the character of the distributions of large particles, it was found that the level of aggregation or micelle formation of the polymer of the viscosity modifier decreases in the used oils. It is shown that the dynamic light scattering method allows to obtain parameters suitable for analyzing the state of engine oil and for obtaining diagnostic data on the state of the engine for used oil. The results obtained are reliable, which is confirmed by repeated testing and general recognition of the effectiveness of the photon correlation spectroscopy method in various fields of science. The reliability of the results obtained is confirmed by the stability of experiments when repeated many times, the correctness of mathematical processing and wide approbation of the methods used in the world practice.