Aerodynamic performance comparison of circular and rectangular S-ducts for aircraft intakes: A CFD study

S-ducts are critical engine inlet components designed to optimize aerodynamics and flight performance, enhance efficiency, and ensure smooth airflow in both aerospace and automotive applications. These ducts are used to direct and deliver airflow to the engine, improving engine performance, increasing fuel efficiency, and minimizing effects such as turbulence. In military jets, S-ducts also serve as structures that enhance maneuverability and absorb incoming radar waves. Additionally, by smoothing the airflow, S-ducts play a significant role in noise reduction. However, secondary flows and flow separation can sometimes occur within S-ducts. These phenomena may negatively impact the performance of S-ducts, leading to a reduction in overall flight performance. In this study, 3D models of circular and rectangular S-ducts were created using SOLIDWORKS to observe variations in velocity, pressure, flow distribution, and kinetic energy within ducts of different geometries. Flow analysis was carried out using the SST k-ω turbulence model in ANSYS Fluent. The analysis produced results for pressure, velocity, and kinetic energy. The findings indicated that although the pressure and velocity distributions were more uniform in the rectangular S-duct, the circular S-duct showed better performance in terms of pressure recovery and distortion coefficient.