The paper intends to overcome the difficulties associated with conventional PIV test techniques in measuring the flow fields near curved surfaces. So the paper combines the visual steady flow test and the CFD simulation method, to help observe the law of particle distribution near the cylinder wall directly, and reveal the law of steady/transient flow field movement and airflow evolution. The results show that the distribution of particle density and the gradient boundary lines of the tracer concentration correspond to those of the CFD simulation. Therefore, a visual test can display the characteristics of the movement of air in the cylinder near the wall. The swirl ratio of each radial section in the cylinder and the ω combustion chamber during the intake stroke is influenced by the intake airflow, while the swirl ratio during the compression stroke is determined by the piston movement. At the end of a compression stroke, the location of the highest swirl ratio directly influences the air-fuel mixture. As a result, analyzing the swirl ratio and evolutionary process of the flow fields near the wall of the cylinder and combustion chamber help improve the quality of the air-fuel mixture and the efficiency of combustion.

本文旨在克服在测量曲面附近流场时与常规PIV测试技术相关的困难。因此，本文将视觉​​稳态流测试和CFD模拟方法相结合，以帮助直接观察圆柱壁附近的颗粒分布规律，并揭示稳态/瞬态流场运动和气流演变的规律。结果表明，示踪剂浓度的颗粒密度和梯度边界线的分布与CFD模拟的分布相对应。因此，视觉测试可以显示气缸内壁附近的空气运动特性。进气冲程期间，气缸和ω燃烧室中每个径向截面的涡流比受进气流量的影响，而压缩冲程期间的涡流比则取决于活塞的运动。在压缩冲程结束时，最高涡流比的位置直接影响空气-燃料混合物。结果，分析气缸和燃烧室壁附近的流场的涡旋比和演化过程有助于改善空气燃料混合物的质量和燃烧效率。