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

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.

粘温效应对十字头滑块与活塞裙润滑影响分析

为了研究船用低速二冲程柴油机关键摩擦副的摩擦动力学问题,本文依据多体动力学和混合润滑的基本原理,考虑润滑油的粘温效应,分析了工作温度下十字头滑块与活塞裙的摩擦学与动力学特性,并与冷态分析结果做了对比。结果表明:在工作温度下,十字头滑块和活塞裙的摩擦损失更小,但二阶运动更剧烈。同时,剧烈的二阶运动使得十字头滑块在发火上止点后,主推力侧的最小膜厚明显降低。

船用低速机十字头滑块和十字头轴承摩擦动力学建模及低摩擦设计

以某型号船用低速机为对象,基于多体动力学和混合润滑耦合建模,研究了十字头滑块和十字头轴承的摩擦动力学性能。利用MEBDF算法对高度非线性和刚性的摩擦动力学方程组进行了求解,得到了各个摩擦副在一个工作循环中的摩擦动力学性能,讨论了滑块供油孔尺寸和十字头轴承宽度对低速机摩擦动力学的影响。计算结果表明:十字头滑块承担发动机的侧推力,摩擦损失较大;十字头轴承在上止点和下止点附近摩擦功率较高;滑块供油孔的半径会影响其摩擦动力学特性;适当降低轴承宽度,能够降低十字头轴承摩擦损失。