Simulation and analysis of strongly asymmetric swirl distortion flow fields

Abstract Driven by the growing demand for stealth and super-maneuverability in modern advanced aircraft, multi-bend inlets such as S-shaped and buried inlets have been widely adopted. While enhancing performance, the swirl distortion induced by such inlets severely restricts engine performance and operational stability. To accurately replicate the complex swirling inlet conditions at the engine face under actual flight, this study uses numerical simulation to investigate the asymmetric multi-vortex flow field at the engine inlet under three typical operating conditions. By rationally designing the turning vanes and supporting structure of the swirl distortion screen, a distortion screen model with high replication accuracy and strong adaptability is constructed, and its simulation results are verified. The results show that the designed swirl distortion screen can effectively reproduce the complex swirl flow field generated by the S-shaped inlet. Under the three typical conditions, the simulated swirl angle curves are close to the real swirl angle curves in overall trend and show high agreement, with average errors of swirl intensity of 7.34%, 3.28%, and 6.02%, respectively.