喷油冷却活塞传热过程的流固耦合分析

Study on Fluid-Solid Coupled Heat Transfer of Oil Spray Cooled Piston

应用ANSYS Fluent软件建立发动机活塞及其冷却结构三维瞬态流-固-热耦合模型,通过燃烧计算得到燃气平均温度与平均传热系数,作为燃烧室壁面热边界;活塞及其冷却结构采用流固耦合计算,使用两相流流体体积(VOF)模型与动网格模拟活塞喷油冷却过程;通过瞬态传热数值仿真,得到活塞振荡油腔流场云图、油气分布云图、冷却油腔传热系数及活塞温度分布,与标定工况下活塞温度测试数据对比分析,研究结果表明:仿真结果与测试数据误差在5%以内,由此说明应用活塞流-固-热耦合仿真方法可以较好模拟柴油机活塞及其冷却结构瞬态传热。

A three-dimensional transient fluid-solid thermal model of piston and its cooling structure was established by using the ANSYS Fluent software. The average gas temperature and heat transfer coefficient obtained from a three-dimension combustion simulation were given as the thermal boundary of combustion chamber and cooling gallery. The piston and its cooling structure were simulated by fluid-solid coupled heat transfer method, and the cooling process of piston spraying oil was simulated by the two-phase flow model of VOF and dynamic meshing. The contours of flow field, distributions of oil and gas, heat transfer coefficient of cooling gallery and temperature distribution of piston were obtained by a transient numerical simulation. The comparison of the measured and simulated piston temperatures at rated condition shows that the deviation between the numerical simulation result and test result is within 5%, which indicates that the fluid-structure-heat coupled method can be used to simulate the transient heat transfer process of engine piston and its cooling structure.