Flow over an airfoil using SOLIDWORKS

OBJECTIVE

• To model the flow over a NACA0017 airfoil for the angle of attacks 0,2,4,6,8,10
• To compare the lift and drag forces.

THEORY ABOUT AIRFOIL

An airfoil (American English) or aerofoil (British English) 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 flow field 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 and the Kutta–Joukowski theorem.

The various terms related to airfoils are defined below:

• The suction surface(a.k.a. upper surface) is generally associated with higher velocity and lower static pressure.
• The pressure surface(a.k.a. lower surface) has a comparatively higher static pressure than the suction surface. The pressure gradient between these two surfaces contributes to the lift force generated for a given airfoil.

The geometry of the airfoil is described with a variety of terms:

• The leading edgeis the point at the front of the airfoil that has maximum curvature (minimum radius).
• The trailing edgeis defined similarly as the point of maximum curvature at the rear of the airfoil.
• The chord lineis the straight line connecting leading and trailing edges. The chord length, or simply chord, is the length of the chord line. That is the reference dimension of the airfoil section.

The shape of the airfoil is defined using the following geometrical parameters:

• The mean camber lineor mean line is the locus of point’s midway between the upper and lower surfaces. Its shape depends on the thickness distribution along the chord;
• The thicknessof an airfoil varies along the chord. It may be measured in either of two ways:
  • Thickness measured perpendicular to the camber line. This is sometimes described as the "American convention";
  • Thickness measured perpendicular to the chord line. This is sometimes described as the "British convention".

Some important parameters to describe an airfoil's shape are its camber and its thickness. For example, an airfoil of the NACA 4-digit series such as the NACA 2415 (to be read as 2 – 4 – 15) describes an airfoil with a camber of 0.02 chord located at 0.40 chord, with 0.15 chord of maximum thickness.

Finally, important concepts used to describe the airfoil's behavior when moving through a fluid are:

• The aerodynamic center, which is the chord-wise length about which the pitching moment is independent of the lift coefficient and the angle of attack.

The center of pressure, which is the chord-wise location about which the pitching moment is zero.

Airfoil Model

Extrude model

PROCEDURE

• Initially go to the curve and select the Airfoil data file and open the airfoil geometry.
• Select the front plane and click on sketch then join the airfoil with the line and then select the entity to copy the geometry and using rotation entity rotate the geometry at different angle (0, 2, 4, 6, 8, and 10).
• Go to the flow simulation click on wizard and give the file name and then we’ll give the other input parameters (velocity=600m/s, fluid=Air).
• Select the external flow and time dependent(total analysis time is 5 sec and output time is 1 sec) and then lick finish
• Computational domain is created by using 2D.
• Select the global mesh and local mesh in that select surface of the model and refine it as level 3.
• After that click on Global goal and select force(x) and force(y) and surface forces(x and y).
• The goal plot is plotted between drag force (in the x direction) and lift force(y direction).
• The same procedure is follow to other angle of attacks.

Input Parameters and conditions

RESULTS

Calculating the drag and lift force at different angle of Airfoil (0, 2, 4, 6, 8, 10)

Case: 1 Angle of attack at 0⁰

^{CUT PLOT}

PRESSURE PLOT

Drag and Lift force

Case: 2 Angle of attack at 2⁰

CUT PLOT

PRESSURE PLOT

Drag and Lift force

Case: 3 Angle of attack at 4⁰

CUT PLOT

PRESSURE PLOT

Drag and Lift force

Case: 4 Angle of attack at 6⁰

CUT PLOT

PRESSURE PLOT

Drag and Lift force

Case: 5 Angle of attack at 8⁰

CUT PLOT

PRESSURE PLOT

Drag and Lift force

Case: 6 Angle of attack at 10⁰

CUT PLOT

PRESSURE PLOT

Drag and Lift force

COMPARISON OF DRAG FORCE AND LIFT FORCE

ANGLE OF ATTACK(Degree)	DRAG FORCE(N)	LIFT FORCE(N)
0	303.807	-0.240
2	332.521	825.385
4	414.405	1641.244
6	551.914	2430.451
8	738.703	3207.553
10	1007.25	4033.382

CONCLUSION

• The above plot and table shows that if the Airfoil angle of attack is increase then the Lift force is changing more compare to the drag force.
• So that the slope of the drag force is lower than the Lift force.

REFFERENCES

• https://en.wikipedia.org/wiki/Airfoil#:~:text=An%20airfoil%20(American%20English)%20or,fluid%20produces%20an%20aerodynamic%20force.