Flow over an airfoil - Solidworks CFD

1. AIM:

- Model the flow over a YS930 IL airfoil over different angle of attacks.

2. INTRODUCTION:

- An airfoil is the cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine).

- 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.

- Angle of attack:

It is the angle at which relative wind meets an Aerofoil. It is the angle formed by the Chord of the aerofoil and the direction of the relative wind or the vector representing the relative motion between the aircraft and the atmosphere.The angle of attack can be simply described as the difference between where a wing is pointing and where it is going.

- Chord line:

An imaginary straight line drawn between the leading edge and the trailing edge of an aerofoil, in the direction of the normal airflow, is referred to as a Chord Line.

- Camber line:

It is defined as the line which depicts convexity of the curve of an aerofoil from the leading edge to the trailing edge.

3. OBJECTIVES:

To model the flow over YS930 IL Airfoil having:

1. Angle of attacks 0, 2, 4, 6, 8 and 10 degrees.

4. FLOW SIMULATION SETUP:

1. First, we need to draw the desired airfoil shape. The selected airfoil is YS930 IL and its curve points in a txt format can be found at: http://airfoiltools.com/airfoil/details?airfoil=ys930-il

2. In solidworks, Navigate here, and then choose the txt file (if txt file is not found on the website, copy the contents under the dat area and paste it in notepad. Also, the option we will be selecting is 'Curve through XYZ points'. Since the database doesn't have Z co-ordinates, put a '0' after every coordinate and do not change the formatting. It should look like this: (Note that we are using MKS system here)

3. After the curve is drawn, on a new sketch, convert it and extrude.

4. Enable the Flow simulation add-in and Open the wizard.

5. Set the velocity in X-direction as 6000`m/s`.

6. On the left side, right click the computational domain and select 2D simulation and the corresponding plane and increase the size of the domain to such an extent that the distance between inflow and airfoil is around 5 times the chord length and the distance between airfoil and exit of the domain is around 10-15 times the chord length.

7. In the Goals section in left side, right click and select surface goals and tick on the Force(X) and Force(Y) in order to get information about the left and drag forces. While selecting, select the top surface and also the bottom(if not selected automatiaclly).

8. For meshing, in addition to the automatic mesh, right click and insert a local mesh and select the top surface. This is done because the goal we have defined has to give accurate outputs while doing external airflow (in this case) and thus we need smaller cells near the surface of airfoil.

9. Run the simulation. A window with preview and goal plot enabled will typically look like this:-

5. OBSERVATIONS, RESULTS AND CONCLUSION:

Note: SG Force X1 is the Drag force and SG Force Y1 is the Lift force.

Case 1: Angle of attack - 0 degrees

Case 2: Angle of attack - 2 degrees

Case 3: Angle of attack - 4 degrees

Case 4: Angle of attack - 6 degrees

Case 5: Angle of attack - 8 degrees

Case 6: Angle of attack - 10 degrees

Combined plots:

Lift Force:

Drag Force:

Conclusion:

- We can say that as angle of attack increases, the Lift force and the drag force also increases. This means lift and drag forces are directly proportional to angle of attack.

- Since we have run the simulation only till 10 degrees, we cannot say that if angle of attack keeps on increasing, the lift and drag force will also increase. Upto a certain degree they will surely increase but after a particular alignment, they will decrease.

- At 90 degrees, the frontal area will be the maximum and the drag force will also be maximum.

- At 90 degrees, the area facing the ground will be miminum, thus lift force will also be minimum.

6. REFERENCES:

- https://en.wikipedia.org/wiki/Airfoil#/media/File:Wing_profile_nomenclature.svg