为了研究缸内直喷汽油机缸内流场、喷雾及燃烧的情况，为后续汽油机的设计开发优化提供依据，基于一台单缸光学发动机，利用粒子图像测速法、米氏散射法及高速摄影法分别测量了缸内流场、喷雾及燃烧情况。结果表明：随着转速的升高，缸内流场逐渐形成了更完整的滚流；随着活塞上行，缸内流场高速区向右侧转移；在压缩过程中，活塞顶对于缸内流场的影响较为明显，速度损失以及流场破坏较为严重。在低速低负荷，由于环境压力较低，喷射的燃料气化坍塌化为雾状，没有明显的多束油束，整体油束雾状明显；随着转速和负荷的增加，在流场的作用下，喷油结束之后在右侧壁面有大量的油滴集聚，可能会导致机油稀释以及池火现象的发生。通过调整喷油器的油束位置，燃烧持续期有了明显的缩短，而平均指示压力（IMEP）保持稳定一致，提升了燃烧的稳定性。

In order to study the in-cylinder flow field, spray and combustion of gasoline direct injection (GDI) engine and provide a basis for the subsequent design, development and optimization of gasoline engine, the in-cylinder flow field, spray and combustion of a single cylinder optical engine were measured by particle image velocimetry （PIV）, Mie scattering method and high speed photography. The results show that the in-cylinder flow field gradually forms a more complete rolling flow with the increase of speed. As the piston goes up, the high-speed area of in-cylinder flow field shifts to the right. In the process of compression, the piston top has obvious influence on the in-cylinder flow field, and the speed loss and flow field damage are serious. At low speeds and low loads, the injected fuel vaporizes and collapses into a mist without visible multibundle beams, and the overall beam mist is noticeable due to the low ambient pressure. With the increase of speed and load, a large number of fuel droplets accumulate on the right side under the action of flow field after fuel injection, which may lead to oil dilution and pool fire phenomenon. By adjusting the fuel beam position of injector, the combustion duration significantly shortens, and the IMEP remains stable and consistent, which improves the combustion stability.