Abstract
This paper studies the influence caused by a vortex generator (VG) on a wing section with NACA 0015 airfoil when this generator is located before and after a recirculation bubble caused by the boundary layer detachment. The study was numerically carried out and concentrated under conditions of flow with Rec = 2.38 × 105 and angles of attack AoA = 3 and 6, characterized by the fact that they undergo detachment of the boundary layer before and after the location of the VG, respectively. The use of the generator in AoA = 3 strongly influenced the reduction of the recirculation bubble, leading to a drag reduction of 1.43%. In AoA = 6 with a bubble recirculation, the effect was much lower, with no well-defined formation of longitudinal vortices, resulting in increased drag and lift at 0.33 and 0.35%, respectively.
Highlights
IntroductionAccording to Schlichting (1979), in low Reynolds (Re) numbers, curved surfaces are susceptible to the detachment of the boundary layer occurring mainly in curved bodies due to pressure distribution gradients
There is a great effort in the aeronautical industry focused on developing means to control the flow on the aircraft, seeking to improve its aerodynamic performance with the increase of the lift and maximum reduction of the drag on the structure.According to Schlichting (1979), in low Reynolds (Re) numbers, curved surfaces are susceptible to the detachment of the boundary layer occurring mainly in curved bodies due to pressure distribution gradients
This paper addressed the influence of a vortex generator on a wing with NACA 0015 airfoil at low angles of attack
Summary
According to Schlichting (1979), in low Reynolds (Re) numbers, curved surfaces are susceptible to the detachment of the boundary layer occurring mainly in curved bodies due to pressure distribution gradients. When this gradient tends to be contrary to the flow direction [dp/dx] > 0), the boundary layer encounters resistance to its development, extending to the point where it detaches from the surface, generating a recirculation region (low pressure), which can increase body drag. Many airfoils operating in Reynolds number as a function of wing chord length Rec < 106 have a separation bubble at angles of attack smaller than the stall angle; just after this bubble, a turbulent boundary layer is observed (Kerho et al 1993). One of the solutions found to delay the occurrence of this detachment is the vortex generators (VG), which for Lin (1999) are small fins or airfoils extended in the normal direction to the surface, being arranged with a slope relative to the direction of the flow
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