Abstract
A crosshead slipper-guide system, which bears a significant thrust force, is an essential friction pair in low-speed marine diesel engines. Owing to the low moving speed of the crosshead slipper during engine startup, it is difficult to form good hydrodynamic lubrication between the crosshead slipper and guide. Therefore, a detailed analysis of the crosshead slipper during engine startup is needed. In this study, a new transient tribo-dynamic model for a crosshead slipper during the engine startup process is presented. The model consists of a mixed lubrication model of the crosshead slipper-guide and dynamic models of the piston assembly, crosshead assembly, connecting rod, and crankshaft. The tribo-dynamic performances of the crosshead slipper during startup and under the rated conditions were simulated and compared. The results show that the tribo-dynamics of the crosshead slipper during the startup process are significantly different from those under the rated conditions. Some measures beneficial for the low friction of a crosshead slipper-guide under the rated conditions may significantly increase the friction loss of the crosshead slipper-guide system during the startup process.
Highlights
In the shipping industry, 20% of the fuel energy is used to overcome friction, which results in significant energy waste [1]
Considering the secondary motion of the crosshead slipper and coupling effects between the piston skirtliner friction pair and crosshead slipper-guide friction pair, the authors of this study established a more accurate tribo-dynamic model to analyze the performance of the crosshead slipper under the rated conditions [4, 12]
When solving the presented tribo-dynamic model, the normal force Fc, the friction force Fcf between the crosshead slipper and guide, and the corresponding torque Mc, Mcf need to be determined through a mixed lubrication analysis
Summary
20% of the fuel energy is used to overcome friction, which results in significant energy waste [1]. Scholars have paid more attention to the tribological phenomena of other friction pairs such as piston rings [13,14,15,16], crosshead bearings [17, 18], and crankpin bearings [19] in low-speed marine diesel engines Such studies have only been carried out under the rated conditions. Considering the secondary motion of the crosshead slipper and coupling effects between the piston skirtliner friction pair and crosshead slipper-guide friction pair, the authors of this study established a more accurate tribo-dynamic model to analyze the performance of the crosshead slipper under the rated conditions [4, 12]. According to the motion and force analysis of the components in low-speed marine diesel engines, the dynamic models of the piston assembly, crosshead assembly, connecting rod, and crankshaft are established. To the best of the authors’ knowledge, the present study marks the first time such a model and its analysis have been described
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