Numerical investigation of miniature vortex generators on an airfoil

Abstract Miniature vortex generators (MVGs) have a large potential to reduce the friction drag by delaying laminar-turbulent transition in boundary layer flows through the attenuation of the growth of Tollmien-Schlichting waves. This study is concerned with the modal stability analysis of the streamwise elongated streaks in the boundary layer on the suction side of an aerodynamic body — the Bluepoint solar car of the Innoptus solar team. Two MVG configurations are investigated: one that was the focus of previous experimental studies and another one that is the recommendation of Szabó et al. (Computers & Fluids, 269, 106123, 2024). Using the methodology of Szabó et al., the stationary flow is calculated with three-dimensional CFD simulation and the boundary region equations, while the modal stability of the flow is modeled using BiGlobal and parabolized stability equations. The MVG location on the airfoil is determined using the results of initial stability calculations. It is shown that because of the low curvature, in the base flow calculation, it is sufficient to represent only the pressure gradient induced by the shape variation and the explicit curvature terms may be neglected. Furthermore, the curvature can also be neglected in the stability calculations, while non-local effects have a more substantial influence on the stability of the flow. Finally, it is shown that in the case of the streamlined body, the recommendations of Szabó et al. derived in the flat-plate boundary layer are not superior, which reveals the need for further research efforts.