Aero-optical aberration characteristics of flow over a cylinder with slit

The large-scale coherent structures generated in the near field of airborne optical systems are the main source of optical distortion. Addressing the urgent demand for improved optical quality, effectively suppressing large-scale vortex structures has become a key challenge. In this study, a combined approach of numerical simulation and ray tracing is employed to systematically investigate the flow structures and aero-optical distortion characteristics of a cylinder with slit. Comparative analyses are conducted for various dimensionless slit widths [Formula: see text], slit angle [Formula: see text] and multiple incident ray angles [Formula: see text]. The results indicate that the jet introduced through the slit effectively reduces the size of vortices in the wake, enhances the uniformity of the density gradient distribution and decreases the optical path difference (OPD). These improvements become more pronounced with increasing dimensionless slit width [Formula: see text], and the same trend is observed for different incident angles. Considering both wake disturbance intensity and optical performance enhancement, it is recommended that a [Formula: see text] range of 0.15–0.2 be selected in practical applications to achieve an optimal performance balance.