Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

摘要

A study emphasizing the effects of passive vortex generators (VGs) on aerodynamic characteristics of a NACA 4415 airfoil is presented. Both experimental and numerical works have been carried out on an array of VGs attached to a NACA 4415 airfoil. Lift and drag measurements are made at various angles of attack by using three-axis component balance system. On the numerical side, Reynolds-averaged Navier-Stokes (RANS) equations have been solved with ANSYS FLUENT 14.5 commercial code with fully structured mesh and three turbulence models (realizable k-epsilon, k-omega shear stress transport [SST] and the Spalart-Allmaras model) at Reynolds number Re = 2 x 10(5). Parametric studies have been conducted to find out optimal configurations with respect to span-wise separation distance between VGs, along with their location along the chord. A very good agreement has been obtained between experimental and computational results indicating that this optimized configuration is robust for the considered parameters. It turns out that increasing the span-wise separation length increases the aerodynamic performances (lift-to-drag ratio) at low attack angles for which low parasitic drag is achieved but conversely degrades it at higher ones. For the stream-wise location along the chord, upstream position of VGs degrades the lift-to-drag ratio at low attack angles and conversely improves it at higher ones.