Aerodynamic Characteristics according to S-Duct Curvature, and Secondary Flow Reduction

Low observable aircraft have a S-Duct to reduce RCS at the engine face.The S-Duct causes flow separation due to curvature, resulting secondary flow affects the performance of the turbofan engine.In this study, a three-dimensional CFD analysis of UAV S-Duct was performed to investigate internal flow according to the curvature, section geometry changes in S-Duct.In addition, jet injection was applied as a way to reduce secondary flow in the duct.The performance of the duct was evaluated in terms of total pressure recovery and distortion coefficient.The computational results show that the performance is better when the curvature point is located rearward than the baseline and the airflow distortion is significantly reduced with jet injection. (AIP) S .S . S (CFD) . Jet injection . (PR) (DC60) . , Jet injection .