Experimental Investigation of Grid Winglet Effects on Aerodynamic Characteristics of a Wing Model at Low Reynolds Number

In this research¡ a low speed wind tunnel test has been carried out to investigate the effects of adding grid winglet¡ its size and number of fingers on the flow pattern over the upper surface of a wing model and its aerodynamic coefficients. The investigation has been performed for different angles of attack ranging from -2 to 21 degrees and at a free stream velocity of 24.7 m/sec¡ corresponding to the Reynolds number of 101000. The model has a rectangular shape with an aspect ratio of 4.75. Wing section airfoil is NACA 23016. Flow visualization is performed using tuft over the upper surface of the wing and lift & drag coefficients are measured. The obtained results show that at low angles of attack (lower than 6 degree)¡ adding the grid winglet has no effect on the lift & drag coefficients. However¡ at higher angles of attack¡ its effect increases. Maximum amount of lift and minimum amount of drag is for the case that the grid winglet has 4 fingers sorted from long to short.