Flow over an airfoil
Aim :- Model the flow over a NACA0017 airfoil
- For the angle of attacks 0,2,4,6,8,10 compare the lift and drag forces
Introduction :- An airfoil is the cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine), or sail (as seen in cross-section). An airfoil-shaped body moving through a fluid produces an aerodynamic force. The component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag. Subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, often with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the working fluid are called hydrofoils. The lift on an airfoil is primarily the result of its angle of attack. When oriented at a suitable angle, the airfoil deflects the oncoming air (for fixed-wing aircraft, a downward force), resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as aerodynamic force and can be resolved into two components: lift and drag. Most foil shapes require a positive angle of attack to generate lift, but cambered airfoils can generate lift at zero angle of attack. This "turning" of the air in the vicinity of the airfoil creates curved streamlines, resulting in lower pressure on one side and higher pressure on the other. This pressure difference is accompanied by a velocity difference, via Bernoulli's principle, so the resulting flowfield about the airfoil has a higher average velocity on the upper surface than on the lower surface. The lift force can be related directly to the average top/bottom velocity difference without computing the pressure by using the concept of circulation.
Angle of attack:- Angle of attack is the angle between the oncoming air or relative wind and a reference line on the airplane or wing. Sometimes, the reference line is a line connecting the leading edge and trailing edge at some average point on the wing.
- Increases as the angle of attack increase the lift force increase proportionately. And a certain point, called critical angle of attack, upper surface ow is more separated and the airfoil or wing is producing its maximum coecient of lift.
- The study of airfoil behavior to varying angle of attacks is made in order to determine the best possible dimensions for practical conditions. In most airplanes, this is about 16 to 18 degrees. During a cruise, the requirement is to maintain the angle of attack where the total drag on the airplane is minimum so as to use the minimum thrust and therefore, minimum fuel consumption. This could occur at an angle of about 3 to 5 degrees.
Cad Model Of NACAA0017 Airfoil : -
########### Result of Simulation :-
- Angle of attack= 0 degree
## Velocity Contour
## Pressure Contour
- Angle of attack= 2 degree
## Velocity Contour
## Pressure Contour
- Angle of attack= 4 degree
## Velocity Contour
## Pressure Contour
- Angle of attack= 6 degree
## Velocity Contour
## Pressure Contour
- Angle of attack= 8 degree
## Velocity Contour
## Pressure Contour
- Angle of attack= 10 degree
## Velocity Contour
## Pressure Contour
##### Comparison Of drag force And Lift force
- Drag Force Vs Angle Of Attack
- Lift Force Vs Angle Of Attack
##### Observations and Conclusion :-
- With increased angle of attack, lift increases in a roughly linear relation.
- Stalling condition will be achieved in range odf 15°-20° angle of attack.