数值仿真在大型二冲程船舶柴油机上的振动特性分析

摘要

采用数值仿真法对某大型二冲程船舶柴油机进行了振动特性研究.为提高数值计算精度,对模型采用全尺寸仿真,并分析了其振动模态和不同转速下的频率响应,为避免柴油机的共振提供设计依据.往复式柴油机的模态阻尼系数取决于结构零件在振动过程中的相互作用和能量耗散率,为解决大型二冲程船舶柴油机振动特性数值仿真时阻尼系数难以选取的问题,采用一种迭代算法,将柴油机看作一种多自由度的弹簧-质量-阻尼系统,逐步迭代出最佳的阻尼系数,并通过实验进行拟合分析,验证了该算法的准确性.%A numerical simulation method was used to study the vibration characteristics of a large two-stroke marine diesel engine, and in order to improve the accuracy of numerical calculation, the full size structure is adopted in the simulation model.The vibration mode and frequency response under different rotating speed were analyzed to avoid resonance of the diesel engine.The modal damping coefficient of the reciprocating diesel engine depends on the interaction of the structural parts in the vibration process and the dissipation rate of the energy.And in order to solve the problem of difficult selection of damping coefficient in numerical simulation of vibration characteristics of a large two stroke marine diesel engine, using a heuristic algorithm, and the diesel engine was regarded as a kind of multi degree of freedom spring mass damper system to get the optimal damping coefficient.The fitting analysis was carried out by experiments, and the accuracy of the algorithm was verified.