Numerical study on adjustment of the main flow field with guide vanes in transition zone for an S-duct

A 30°/30° S-duct is often employed by a modern civil and military aircraft. Due to the vortex generators have poor control effect on the flow separation in the large curvature S-duct, so a new method adjusting the direction of the main flow in the transition zone for S-duct is proposed in the present study. These studies are carried out by solving Navier-Stokes equations with SST k-ω turbulence model. In order to explore the control mechanism of guide vanes on the flow field for S-duct, the internal flow field of S-duct with/without guide vanes is analyzed and compared in detail, including the velocity distribution on the symmetry plane, the secondary vortex intensity at different cross sections, turbulent kinetic energy on different cross sections, total pressure distribution on different cross sections, three-dimensional streamline, and so on. The results show that guide vanes can not only effectively adjust the direction of the main flow, but also restrain the flow separation, reduce the total pressure loss, and improve the uniformity of flow field.