气缸套变形多场耦合建模与分析技术

为完善气缸套变形分析技术,以V型柴油机为研究对象,考虑气缸套材料的非线性温度效应与构件间的接触非线性影响,建立气缸套变形分析有限元模型.应用流固耦合方法获得水套壁面传热边界条件,将气缸盖和气缸套的温度场耦合于缸套变形计算中,得到气缸套的截面变形量.借助离散傅里叶变换分析方法对气缸套变形进行分解,明确气缸套变形特征,并分析了变形影响因素,在此基础上,探讨了冷却水套入口冷却液温度与气缸套变形之间的关联性,总结出缸套变形的影响规律.结果表明:气缸套上端截面变形受温度和缸盖螺栓预紧力的影响大,气缸套中下部截面变形受温度影响小.适当选择冷却水套入口冷却液温度范围可有效控制气缸套变形量,该分析方法为柴油机气缸套多场耦合分析设计方法提供重要技术参考.     

Experimental study on compression stroke characteristics of free-piston engine generator

The compression stroke characteristics of free-piston engine generator were studied. The numerical model of the compression stroke was established based on thermodynamics and dynamics equation, and the leak loss, heat loss and friction loss were considered. Through solving numerical equations, the in-cylinder pressure of compression stroke under different compression ratios was calculated, energy transfer and conversion process was analyzed, and the calculated results were experimentally verified. The results showed that the actual effective output of electronic energy and the compression energy stored in the compressed gas accounted for about 70%. The compression energy gradually increased with the increasing compression ratio. When the compression ratio was more than 7.5, the actual compression energy increased slowly and the energy error between simulation and test decreased.