Design Of High-Lift Airfoil For Formula Student Race Car

A two-dimensional model of three elements, high-lift airfoil, was designed at a Reynolds number of 10(6) using computational fluid dynamics (CFD) to generate downforce with good lift-to-drag efficiency for a formula student open-wheel race car basing on the nominal track speeds. The numerical solver uses the Reynolds-averaged Navier-Stokes (RANS) equation model coupled with the Langtry-Menter four-equation transition shear stress transport (SST) turbulence model. Such model adds two further equations to the k - omega SST model resulting in an accurate prediction for the amount of flow separation due to adverse pressure gradient in low Reynolds number flow. The k - omega SST model includes the transport effects into the eddy-viscosity formulation, whereas the two equations of transition momentum thickness Reynolds number and intermittency should further consider transition effects at low Reynolds number. Starting with a baseline design using the understanding of high-lift airfoils, all elements were arranged using an Eppler E421 profile. The lift coefficient was improved by varying the flaps' overlaps, gaps, and deflection angles sequentially, thus testing 31 rigging combinations. Finally, these data were plotted to choose the best rigging in terms of maximum lift coefficient and to better understand the sensitivity of lift and drag coefficients to these parameters. Lift coefficient improved by 8.9% compared to the baseline design. It was also found that the lift coefficient increased 5.9 times when compared to a single-element Eppler E421 airfoil.