Gil-Prieto, DanielMacManus, David G.Zachos, Pavlos K.Tanguy, GeoffreyWilson, FrançoisChiereghin, Nicola2017-04-122017-04-122017-03-31Daniel Gil-Prieto, David G. MacManus, Pavlos K. Zachos, Geoffrey Tanguy, François Wilson, and Nicola Chiereghin. Delayed detached-eddy simulation and particle image velocimetry investigation of S-Duct flow distortion. AIAA Journal, 2017, Vol. 55, Iss. 6, pp1893-19080001-1452http://dx.doi.org/10.2514/1.J055468https://dspace.lib.cranfield.ac.uk/handle/1826/11761The dynamic flow distortion generated within convoluted aeroengine intakes can affect the performance and operability of the engine. There is a need for a better understanding of the main flow mechanisms that promote flow distortion at the exit of S-shaped intakes. This paper presents a detailed analysis of the main coherent structures in an S-duct flowfield based on a delayed detached-eddy simulation. The capability of this numerical approach to capture the characteristics of the highly unsteady flowfield is demonstrated against high-resolution, synchronous stereoscopic particle image velocimetry measurements at the aerodynamic interface plane. The flowfield mechanisms responsible for the main perturbations at the duct outlet are identified. Clockwise and counterclockwise streamwise vortices are alternately generated around the separation region at a frequency of St=0.53 St=0.53 , which promote the swirl switching at the duct outlet. Spanwise vortices are also shed from the separation region at a frequency of St=1.06 St=1.06 and convect downstream along the separated centerline shear layer. This results in a vertical modulation of the main loss region and a fluctuation of the velocity gradient between the high- and low-velocity flow at the aerodynamic interface plane.enAttribution-Non-Commercial 3.0 Unported (CC BY-NC 3.0) You are free to: Share — copy and redistribute the material in any medium or format, Adapt — remix, transform, and build upon the material. The licensor cannot revoke these freedoms as long as you follow the license terms. Under the following terms: Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. Information: Non-Commercial — You may not use the material for commercial purposes. No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.Article