A tribological analysis on stuffing box-piston rod system of low-speed marine diesel engines

Abstract

The stuffing box-piston rod system is widely used in the low-speed marine diesel engines to scrape oil and ensure sealing. Its friction power loss and wear rate are great, but the studies about the system are very limited. In this study, based on the special structure and working conditions of the stuffing box, the analytical model for the tribological properties of the stuffing box-piston rod system is developed considering the oil starvation and relative ring location effects. The minimum oil film thickness, friction, oil transportation, and asperity contact are calculated for the stuffing box. The analysis results show that compared with the fully flooded lubrication, the minimum oil film thicknesses of the rings reduce significantly in the middle of the strokes under the starved lubrication condition, but the friction losses of the rings are influenced by the comprehensive effects of the oil film thickness reduction and lubricating area reduction under the starved lubrication condition, which is related to the specific profiles of the rings. In addition, compared with the engine piston ring pack, the relative ring location effect is more obvious in the stuffing box ring pack because there are more rings and the ring intervals are larger. The relative ring location effect makes the minimum oil film thicknesses, friction forces, and asperity contacts of the rings have oscillations after bottom dead center and top dead center.

Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup

“…The related numerical method for dealing with the oil transport and starved lubrication conditions can be found in previous studies [10,15].…”

“…In the current study, the Reynolds boundary condition was adopted. The cavitation boundary condition can be expressed according to the following Reynolds boundary condition [10]:…”

“…Low-speed two-stroke crosshead marine diesel engines (hereafter referred to as low-speed marine diesel engines) have been widely used for propulsion power in commercial ships of more than 2 kt [10,11] owing to their high thermal efficiency and reliability. Unlike high-speed automobile engines, low-speed marine diesel engines operate at a rotation speed lower than 300 rpm and have a crosshead slipper-guide system allowing them to bear an enormous thrust force.…”

Impact of Pilot Injection on Combustion and Emission Characteristics of a Low-Speed Two-Stroke Marine Diesel Engine

“…Different from the high-and medium-speed ships that generally use four-stroke diesel engines, low-speed marine ships, which dominate the long-distance transportation industry of global goods, normally use two-stroke engines. Compared to four-stroke engines, two-stroke low-speed marine diesel engines have the distinct advantages of higher torque, better fuel efficiency, as well as higher power density, which make them excellent power sources [3] for global long-distance transportations [4]. However, on the other hand, the two-stroke diesel engines may cause considerable pollution to the environment [5].…”

Influential factors on pressure characteristics of fuel system for a low-speed marine diesel engine

“…1,2 Diesel engine could be divided into high-speed diesel engine, medium-speed diesel engine and low-speed diesel engine according to engine speed. When compared with medium- and high-speed diesel engine, low-speed marine diesel engine (LSMDE) is characterized by high torque, thermal efficiency and power, 3 which is the most suitable power source of ocean transportation. 4 However, the diesel engine not only makes great contribution to the development of world economy but also causes great damage to the environment.…”