| Summary: | Aerodynamic efficiency loss in airfoils is primarily due to the increased
drag caused by boundary layer separation, especially at low Reynolds number. To
reenergise the boundary layer and delay flow separation, cavities are introduced on
the suction side of the airfoil. A cavity is a passive flow controller used to overcome
a higher adverse pressure gradient and energise the low momentum boundary
layers near the airfoil surface. In this paper, a total of 6 different airfoils is chosen
to study the effect of the cavity and its design specification in term of size, shape,
location, and number. The modified airfoils will be constructed in SOLIDWORKS
and tested in PROFILI software which uses the XFOIL interface to calculate the
airfoil's lift coefficient (Cl), drag coefficient (Cd), lift -to- drag ratio (l/d). It was
found that the Clark y benefits the most when the cavity is introduced on the
airfoil's suction side. Among the four different oval shapes, Oval Os provides a
better l/d for Clark y, GEMINI and E387 airfoils, where the l/d increase by
11.41%,1.22% 0.015%, respectively. Besides that, among the four different sizes,
the cavity with 0.01 w/c gives the best aerodynamic performance to Clark y airfoil
where the l/d of the airfoil is increased 9.03%. Apart from the Clark y airfoil, the
cavity with 0.01w/c also helps to reduce the Cd of GEMINI. E387 and NLF0416
by 4.80%, 6.42% and 4.59% respectively. From the analysis on the number of
cavities, it was found that the single cavity works better for some of the airfoils,
especially for Clark y airfoil. Moreover, for the multipole cavity, the Cd of the
GEMINI, NLF 0416 and E387 airfoils is reduced; unfortunately, the airfoil's Cl
also decreases, affecting the aerodynamic performance.
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