Numerical investigation of flow over multielement airfoils with lift-enhancing tabs

The flow over multi-element airfoils with flatplate lift-enhancing tabs placed near the trailing edge of main element or/and flap was numerically investigated for different flap riggings. The 2D unsteady Reynolds-Averaged Navier-Stokes (RANS) equations together with the two-equation SST k-ω turbulence model were applied to this numerical simulation utilizing the multi-block structured grids of C-H type. The effects of local grid near the liftenhancing tabs on computational results and also various tabs were studied for McDonnell Douglas Aerospace three-element airfoils consisting of a slat and single-slotted flap. Numerical results showed that the impact of liftenhancing tabs on the performance of multielement airfoils depended on the location and height of tabs and multi-element configurations. The cove tab could reduce the amount of separated flow on the flap being in nonoptimum position, whereas the flap tab could substantially increase the lift of multi-element airfoils for different configurations, and the combination tab was approximately a linear combination of the changes caused by the individual tabs.