Numerical simulation and optimization design of the EGR cooler in vehicle

The EGR (exhaust gas recirculation) technique can greatly reduce the NOx emission of diesel engines, especially when an EGR cooler is employed. Numerical simulations are applied to study the flow field and temperature distributions inside the EGR cooler. Three different models of EGR cooler are investigated, among which model A is a traditional one, and models B and C are improved by adding a helical baffle in the cooling area. In models B and C the entry directions of cooling water are different, which mostly influences the flow resistance. The results show that the improved structures not only lengthen the flow path of the cooling water, but also enhance the heat exchange rate between the cool and hot media. In conclusion we suggest that the improved structures are more powerful than the traditional one.

基于流固耦合的EGR冷却器失效分析及优化研究

针对某板翅式废气再循环(EGR)冷却器出现的开裂问题,对EGR冷却器进行了基于流固耦合的失效分析及结构优化。基于Fluent与ABAQUS,建立了EGR冷却器流固耦合分析流程,对EGR冷却器内流场、固体部分进行了流体力学与有限元流固耦合计算,对流体温度、传热系数与固体温度、热应力、等效塑性应变、应力幅之间的联系进行了研究,得出了EGR冷却器失效形式为循环热载荷导致的高应力低周疲劳断裂;利用电境扫描得到了微观断口形貌,对流固耦合分析结果进行了验证,并提出了在冷却管两侧加装副主片以减少单位面积受力的优化方案。研究结果表明:基于Fluent与ABAQUS的流固耦合计算,对于EGR冷却器的失效分析及优化是可行的。