Influence of Airfoil Camber on Flow Behavior & Aerodynamic Coefficients & Influence of Thickness Ratio on Drag Coefficient

ADENIRAN OLUOKUN

Introduction

• Two Airfoils are analyzed to determine the influence of

camber on aerodynamic characteristics.

• NACA 0012 (symmetric)

• NACA 2412 (Cambered)

• The both have the same

• Chord length ( 0.2 m)

• Span (0.05 m)

• Position of Maximum thickness (12% )

1

Computational Model

2

Inflated airfoil mesh

Computational model

Setup of Computation• Boundary conditions

• Constant free stream velocity U∞= 5 m/s.• At temperature 250C • 1 atm reference pressure• No heat transfer, no turbulence model• No slip at the airfoil walls• Domain boundaries of free slip• Outlet conditions of zero gauge average static pressure.

3

Computational domain

Results• Grid convergence

• The result for the lift coefficient is plotted for 3 mesh sizes

• 0.006 m mesh is chosen since it gives smoother result

4

Influence of airfoil camber on aerodynamic coefficients

• Cambered airfoil produces greater lift & lift to drag ratio

5

• Influence of airfoil camber on Flow behavior• Total pressure For symmetric airfoil at 0, 8,12,& 15 degrees

angle of attack

6

• Influence of airfoil camber on Flow behavior• Total pressure For cambered airfoil at 0, 8,12,& 15 degrees

angle of attack

7

• Influence of varying the thickness ratio• As the thickness % is increased Drag coefficient increases

• Influence of Varying Reynolds number on drag coefficient• As the speed is increased the drag coefficient reduces

8

• Boundary layer thickness and separation• Separation occurred at x=0.082 m then flow reattaches• A final separation occurs at x=0.18 m which is very close to the trailing edge

• Conclusion• The camber of an airfoil is important for delay of boundary layer separation• The results gotten from the simulation at the same Reynolds number (65000) for the

NACA0012 and NACA2412 shows the stall angles to be 11.60 and 14.80 respectively.• Separation will lead to lift as well as drag generation. • Lower Reynolds number generates more drag on an airfoil• The sharp peaks of the wall shear stress after separation are seen to be due to

transition of boundary layers from laminar to turbulent 9

x (m) y (m) UT (m/s) du dy τw/µ (1/s) δ (m)0.000702 0.000154 3.135554 1.28E-07 5.52E-06 0.023282 0.0055130.007136 0.007698 4.12E-06 1.34E-10 2.90E-06 4.62E-05 0.0020880.016758 0.010229 3.367934 1.50E-10 5.51E-06 2.72E-05 0.0018840.031709 0.013356 5.675004 0.041262 5.56E-06 7424.083 0.0019670.057865 0.015645 6.04E+00 0.030707 5.50E-06 5579.344 0.0023490.080487 0.015614 -0.41172 -0.00854 5.50E-06 -1551.55 00.080487 0.015614 -4.12E-01 0.00582 5.50E-06 1058.182 0.0041220.126845 0.011869 8.33E-01 2.83E-05 5.59E-06 5.059576 0.0055340.148499 0.0091 1.35E-01 0.001567 5.58E-06 280.8696 0.0003930.167461 0.006197 2.49E+00 0.000562 5.56E-06 101.144 0.005534

0.18278 0.003525 4.074433 -0.02198 5.57E-06 -3946.1 0.005551