Simulation Analysis and Experimental Verification of Tribodynamics of Reciprocating Friction Pairs in Low-Speed Marine Engines

Abstract

The performance of reciprocating friction pairs in low-speed marine diesel engines has an important impact on the economy, stability, and safety of the ship operation, which deserves special attention. However, the available research is very limited. In this article, a new tribodynamics modeling method and an online measurement method for friction force are proposed. The friction force is simulated and verified by experiments. Based on the principle of multibody dynamics and mixed lubrication theory, a tribodynamic model coupling the reciprocating friction pairs (piston assembly–cylinder liner, piston rod–stuffing box, and crosshead slipper–guide) is first established. The friction force and dynamics are theoretically analyzed. Then a friction measurement method, which can measure the friction force of reciprocating friction pairs under engine firing conditions, is developed and used to verify the simulation. By comparison, it is found that the simulated friction is in good agreement with the experimental one. The results show that the crosshead slipper and piston assembly have obvious secondary motion, which will affect the vibration and noise of the engine. The friction force of the piston assembly is much higher than that of other reciprocating friction pairs. Improving the lubrication state near the top dead center of the piston assembly is of great significance to reduce the friction loss of the low-speed marine engines.