Quasi-3D inverse design of S-shaped diffuser with specified cross-section distribution; super-ellipse, egg-shaped, and ellipse

Recently, an inverse design method called the ball spine algorithm (BSA) is introduced to design S-duct diffusers with elliptic cross-sections. The technique is developed for the 3-D design of S-shaped ducts with special cross-sectional profiles in the present work. The upper and lower lines of the S-duct symmetric section are modified under the BSA. Two types of special cross-section profiles are used to improve the aerodynamic properties of the duct. At the S-duct inlet, the super-ellipse profile is used to minimize the duct inlet height. At the aft part of the duct, the egg-shaped profile is predefined to decrease the pressure difference between the upper and lower lines and to diminish the adverse pressure gradient along the upper line. Finally, the flow through the designed S-duct is numerically analyzed using a viscous flow solver with the SST turbulence model to validate the designed S-duct performance.