喷油器中置直喷汽油机缸内湿壁特性分析及优化

Analysis and Optimization of In-cylinder Spray Impingement Characteristics in a GDI Engine with a Centrally Mounted Injector

利用定容喷雾试验装置及可视化单缸光学发动机,试验研究了汽油机中置喷油器喷雾及燃烧特性,结合模拟仿真软件分析了燃油湿壁的主要影响因素,明确了缸内湿壁与喷雾特性的关系,针对湿壁问题提出了优化设计方案。研究结果表明,采用多次喷射,可有效减小单次喷射的油束贯穿距离,从而减小湿壁的可能性。根据工况匹配合适的喷油正时,可有效减小油束对活塞顶的冲击。通过优化喷雾锥角和喷雾落点等参数,可降低油束冲击活塞顶和气缸壁的几率,并有效减少气缸壁油膜的累积量。

The spray characteristics and combustion process of a centrally mounted multi-hole injector are experimentally researched on the constant volume bomb bench and optical single cylinder gasoline engine, which couples with CFD simulation showing that spray characteristics has an impact on the spray impingement in cylinder and then optimizing the injector for reducing wall films. The research also shows that spray penetration could be reduced by multi-injection to avoid spray impingement upon cylinder wall. Appropriate injection strategy responding to various engine operating condition has an effect on spray impingement upon piston. Spray characteristics such as spray angle and mass distribution are finally investigated and optimized to reduce wall films, which is proved to be helpful to decrease HC and PM emission.