Measurement of the friction force of sliding friction pairs in low-speed marine diesel engines and comparison with numerical simulation

Abstract

Low-speed marine diesel engines are widely used as propulsion power equipment on ocean-going merchant ships. There are three important sliding friction pairs in the engine: piston assembly-cylinder liner, piston rod-stuffing box, and crosshead slipper-guide. They greatly influence the mechanical efficiency and stability of the engine. However, there is no effective method to measure the friction of the three friction pairs so far, which limits the improvement of tribological performance and the reduction of fuel consumption in low-speed marine diesel engines. In the current study, an indirect measurement method is presented and the measurement of the friction force under fired conditions is realized for the first time. By comparing the experimental results of friction force with the model-based numerical results, it is found that they are in good agreement. The difference between the numerical and experimental maximum friction force is less than 5%. Both theory and experiments show that the friction force reaches the maximum after the top dead center, which is about one-tenth of the gas force. The work of this paper is expected to provide an effective tool for evaluating the tribological performance of marine diesel engines.