活塞敲击引起的缸套振动响应对缸套水侧空化的影响研究

Influence of Cylinder Liner Vibration Response Induced by Piston Slapping on Cavitation

为研究活塞侧击引起的缸套振动响应对柴油机缸套水侧空化状况的影响,以某国Ⅵ水冷柴油机为研究对象,结合结构动力学与计算流体力学,对缸套表面振动与其水侧流体动力学行为进行耦合分析。基于柴油机试验台架实测了缸套壁面振动,对应建立了柴油机气缸总成瞬态动力学模型,结合仿真与实测振动响应研究了活塞侧击作用下的缸套振动特性。然后,将瞬态动力学计算结果以动网格的形式输入二维冷却水套模型中进行数值模拟,研究了缸套振动形式、水套厚度和出口压力等因素对空化的影响。结果表明,缸套在活塞侧向力作用下的高频振动与其结构固有模态有关,缸套的高频模态振动和冷却水套厚度对缸套水侧的空化现象影响显著。提高冷却水套出口压力可小幅削减空化强度,而增加水套厚度对缸套水侧空化的抑制作用更为明显。

In order to study the influence of the cylinder liner vibration response induced by the side slapping of piston on the water-side cavitation of cylinder liner,a ChinaⅥwater-cooled diesel engine was taken as the research object and the coupling analysis of the cylinder wall vibration and the water-side hydrodynamic behavior was carried out by combining structural dynamics and computational fluid mechanics.The cylinder liner wall vibration was measured on the diesel engine test bench,the transient dynamic model of cylinder assembly for diesel engine was established,and the vibration characteristics of cylinder liner under the piston side slapping were studied based on the simulation and the measurement.Then the transient dynamics calculation results were input into the two-dimensional cooling water jacket model in the form of a moving grid for numerical simulation and the influence of factors such as cylinder liner vibration form,water jacket thickness and outlet pressure on cavitation were studied.The results show that the high frequency vibration of cylinder liner is related to the natural mode of structure under the side force of piston and the high-frequency modal vibration of cylinder liner and the water jacket thickness have significant effect on the cavitation of cooling water field.Increasing the outlet pressure of water jacket can slightly reduce the intensity of cavitation,while increasing the water jacket thickness has a more pronounced effect on suppressing the cavitation on the water side of cylinder liner.