振荡冷却活塞温度场及热机耦合分析

为分析内冷油腔对活塞的降温效果，对振荡冷却活塞在热负荷、机械负荷及热机耦合作用下的温度场及应力应变分布规律进行研究。采用VOF（volume of fluid）多相流模型、动网格技术等对活塞内冷油腔内机油的振荡传热过程进行Fluent数值模拟，得到内冷油腔各壁面换热系数；将结果映射到活塞固体表面，对活塞分别加载热负荷、机械负荷以及热机耦合作用，对比分析活塞在内冷油腔冷却前后的温度场变化，得到其热应力、机械应力以及耦合应力的变化规律。结果表明，采用内冷油腔进行冷却后，活塞各区域温度均有不同程度下降，其中活塞最高温度下降7.5%；活塞受热机耦合作用下的最大应力小于两者单独作用的结果之和；进行油腔振荡冷却后，活塞的热应力和耦合应力也有不同程度降低。所得到的活塞在内冷油腔冷却前后的应力分布规律，可为活塞内冷油腔的优化设计提供理论参考。

Analysis of temperature field and thermo-mechanical coupling of oscillating cooling piston

In order to analyze the cooling effect of the internal cooling oil gallery on the piston, the temperature field and stress-strain distribution law of the oscillating cooling piston under thermal load, mechanical load and thermo-mechanical coupling were studied. The VOF(volume of fluid) multiphase flow model and dynamic mesh technology were used to simulate the oscillatory heat transfer process of the oil in the internal cooling oil gallery of the piston, and the heat transfer coefficient of oscillating cooling oil gallery was obtained. The data were mapped to the solid surface of the piston. The piston was loaded with thermal load, mechanical load and thermo-mechanical coupling load, respectively, to analyze the temperature field changes of the piston before and after using oscillating cooling oil gallery, and the distribution laws of thermal stress, mechanical stress and coupling stress of the piston before and after using oscillating cooling oil gallery were compared and analyzed. The results show that the temperature in each region of the piston decreases to different degrees after oscillating cooling, with the highest temperature of the piston decreasing by 75%; The maximum stress of the piston under the thermo-mechanical coupling action is less than the sum of the results of the two separate effects; After oscillating cooling, the thermal stress and coupling stress of the piston also decrease in some degrees. The stress distribution law of piston before and after cooling in the internal cooling gallery is obtained, which provides some theoretical reference for the optimization design of the internal cooling oil gallery of the piston.