Transient tribo-dynamic analysis of crosshead slipper in low-speed marine diesel engines during engine startup
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ISSN 2223-7690 CN 10-1237/TH
RESEARCH ARTICLE
Transient tribo-dynamic analysis of crosshead slipper in lowspeed marine diesel engines during engine startup Rui LI1,2, Xianghui MENG1,2,*, Jingjin DONG3, Wenda LI3 1
State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, Shanghai 200240, China
2
School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China
3
China Shipbuilding Power Engineering Institute Company Limited, Shanghai 201206, China
Received: 25 March 2020 / Revised: 13 June 2020 / Accepted: 16 July 2020
© The author(s) 2020. 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. Keywords: low-speed marine diesel engine; crosshead slipper; engine start-up; mixed lubrication; friction loss; tribo-dynamic model
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Introduction
In the shipping industry, 20% of the fuel energy is used to overcome friction, which results in significant energy waste [1]. The friction of a ship can be defined as internal or external [2]. Internal friction refers to the friction generated by various machines inside the ship, and external friction refers to the friction generated between the hull and the ocean. Research results have indicated that the friction loss of marine diesel engines is the primary source of internal friction [2–4]. To deal with a shortage of energy and environmental protection issues [5–9], the development of low-friction technology for marine diesel engines has become an urgent requirement of engine manufacturers.
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 sl
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