Abstract:
Controlling flow separation is one of the most important techniques for reducing drag and increasing the lift-todrag ratio. The aim of this study is to enhance the aerodynamic performance of NACA 4412 airfoil through passive
method of controlling flow separation. Accordingly, as a method of passive control, the geometry of airfoil has
been modified with tangential internal slots. The commencement of each slot is kept constant at 0.05 chord(C)
from the leading edge. The exit positions of the slots are varied vertically at 0.4C slot exit. So, two parameters
have been varied: slot width and vertical slot exit position. The angles of attack (AoA) are varied from 00
to 26
0
with 20
increments for every parameter with a fixed Reynolds number of 1.6×106
. Pressure-based solver and k-ɷ
SST model are used for analysis. For all the slot configurations, better aerodynamic performance in terms of liftto-drag ratio occurs at the moderately higher angles of attack. Among the vertical exit position, the lowermost
position shows better aerodynamic performance. Tapered slot having slot exit width 2%C has higher lift-to-drag
ratio than that of the other configurations from AoA 60
to the end. However, the highest lift-to-drag ratio is found
at AoA 80
for all the modified designs whereas it happens at AoA 60
for the airfoil with no slot. Moreover, for this
configuration, the stalling angle of attack is delayed to AoA 240 whereas for other configurations the stall angle
gradually decreases and for no slot, it is the lowest which is AoA 160.
