Numerical simulation of compressible flow in a diffusing s-duct with and without vortex generators

This paper aims to report the computational research carried out to study the flow in a diffusing S-duct using Computational Fluid Dynamics (CFD). Computations were carried out for the two cases of an S-duct without flow control devices and an S-duct with passive flow control devices (vortex generators). The complexities of the flow field such as separation, secondary flows, and flow accelerations will be demonstrated in each case. The accuracy and validity of the numerical results are judged by their ability to match the experimental data reported in the AIAA Propulsion Aerodynamics Workshops (PAW01). For this purpose, RANS equations will be solved using the unstructured flow solver called Tenasi. Wilcox's Reynolds Stress Model (RSM) and Menter's Shear Stress Transport (SST) turbulence models were used in calculations to obtain steady state solutions. A grid study was done for each case using a coarse, medium and fine mesh. Generally, reasonable agreement was found, and the results show that the CFD solver used was able to capture the flow physics and performance characteristics.