重型柴油机湿式缸套穴蚀损伤差异的数值模拟研究

本文针对某款重型柴油机在爆压提升前、后出现的穴蚀差异,提出了一种综合缸套振动变形与冷却液空化的耦合建模方法。首先基于活塞-缸套瞬态动力学模型,获取了缸套主副推力侧在活塞侧击作用下的动态响应,并通过台架试验进行了校验。然后,将仿真的振动信号以动网格形式输入流场,研究了缸套振动激励下两款柴油机不同水腔区域的空化波动特性,并结合实验与数值模拟解析了高爆压柴油机缸套穴蚀显著的主要原因。结果表明,缸套在活塞侧击作用下的振动响应与其约束模态有关,流场的空化强度与缸套振动幅值并非线性相关,而是与缸套的振动频率和模态振型存在耦合相关关系。这些研究成果为缸套穴蚀倾向的预测研究提供了新的思路与方法。

Numerical Investigation into the Difference of Cavitation Damage in the Wet Cylinder Liner of Heavy-Duty Diesel Engine

In this paper, a coupling modeling method combining cylinder liner vibration deformation and coolant cavitation was proposed for investigating into the cavitation difference of heavy-duty diesel engines before and after combustion pressure lifting. Based on the transient dynamic model of piston-cylinder liner, the dynamic response of the cylinder liner to side impact of the piston was simulated and verified by the bench test. Then, the simulated vibration signals were input into the flow field in the form of grid deformation. The cavitation fluctuation characteristics in different flow fields of two diesel engines under excitation of cylinder liner vibrations were studied, and the main reasons for the significant cavitation of cylinder liner excited by explosion pressure are analyzed. The results show that the vibration response of the cylinder liner to piston side impact is related to its constrained modes, and the cavitation intensity of the flow field is not linearly correlated with the vibration amplitude of the cylinder liner. But it is found that there is a coupling correlation between cavitation intensity and vibration frequency and mode shapes. These research results provide new ideas and methods for the prediction of cylinder liner cavitation tendency.