某4缸乘用车柴油机冷却水套的设计优化

介绍了长城汽车研发的一款高性能"2.0VGT"柴油发动机冷却水套的设计优化过程,该发动机在进行可靠性试验过程中发现缸盖第1缸鼻梁区存在裂纹,导致冷却水渗入燃烧室发生失火。经过CFD模拟分析,采用优化垫片水孔结构,调整水孔上水量,得到优化后方案整体压力场,局部速度、对流传热系数、温度场的分布等均比优化前有明显改善。特别是优化后方案提高了缸盖第1缸鼻梁区(排气道与喷油器之间水路)冷却水的流速,避免了鼻梁区由于热负荷较大而导致的结构断裂问题。

Cooling Water Jacket Design Optimization of Four-Cylinder Vehicle Diesel Engine

The cooling water jacket design optimization for a high performance 2.0 VGT diesel engine developed by Great Wall Motor Corporation was described.In engine reliability test,it was found that the No.1 cylinder head cracked at valve bridge area and coolant leaked into combustion chamber,causing misfire in the cylinder.That indicates there exists local lower flow velocity and heat transfer coefficient points in the head.Through optimization of gasket holes,cooling water pressure distribution and local velocity,heat transfer coefficient and cylinder head temperature field are improved significantly.Special attention is paid to increase cooling water velocity around the valve bridge area of cylinder No.1,avoiding its structure failure due to excess heat stress.