A Comparative Analysis of Flow Control Methods: The Superiority of Vortex Generators for Diffuser Efficiency

Flow separation under adverse pressure gradients critically limits diffuser performance. This study investigates the use of Rectangular and Delta Wing Vortex Generators (RWVGs and DWVGs) to mitigate separation and enhance aerodynamic efficiency. Experiments measured diffuser efficiency, wall shear stress, and stagnation pressure loss across Reynolds numbers (Re = ۱۳,۲۵۰ - ۴۳,۰۰۰) for a smooth diffuser and cases fitted with single and paired WVGs. All WVG configurations significantly improved performance over the smooth one. The three-pair RWVG configuration was optimal, achieving the highest efficiency ratio (η/ηs) by balancing flow control with frictional losses. The diffuser roughened with RWVGs increased wall shear stress by ۶۰-۸۰%, indicating effective boundary layer energization and attached flow, which reduced stagnation pressure loss by up to ۲۵%. The results showed that WVGs suppress separation; their shape, arrangement, and density are paramount. An optimal design maximizes efficiency by generating sufficient vorticity to maintain attachment without introducing excessive viscous drag. These findings provide practical guidelines for designing high-efficiency diffusers in aerodynamic and energy systems.

کلیدواژه ها:

Diffuser efficiency ، Wing Vortex Generators ، flow separation ، Wall shear stress ، Stagnation pressure loss