Flow over an airfoil

Objective: To model the flow over a NACA0017 airfoil

Problem Statement:

• Model the flow over a NACA0017 airfoil
• For the angle of attacks 0,2,4,6,8,10 compare the lift and drag forces

Theory:

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 Airflight 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.

Study Setup:

Use the Naca_Airfoil to obtain the link for the NACA0017 airfoil text file.

Then add this file using the browse option provided in the curve file window.

After adding the file perform the necessary changes such as the angle and closing the curve then extrude it to 0.2 m.

Use the flow wizard and select the default options and look for the windows given below to change the properties.

Choose the External Analysis type and Total analysis time to be 5s and Output time step as 1s.

Select Air as the fluid and click on the Next button.

In Velocity Parameters, change the velocity in X direction to be 600 m/s.

Add the surface goals as shown in the figure.

Insert the local mesh as shown in the figure.

Create a Cut plot as shown above.

Create a Goal Plot as shown above.

Procedure:

1. Search for the Naca0017 Airfoil and copy the data into a notepad and save it as a text file.
2. Then Open Solidworks and create a new part.
3. Move to the Insert - Curve - Curve through XYZ points and using the browse option add the file containing the airfoil data.
4. Close the Open curve using the line. Then adjust the angles based for each part varying from 0,2,4,6,8,10.
5. Extrude the sketch by 0.2 m.
6. Save the part with a file name.
7. Use the wizard option given in the Flow Simulation and follow the steps given in study setup above.
8. Adjust the computational domain by making sure the right amount of space is maintained between the ends of the domain and the part. Make sure that the domain is performing 2D simulation.
9. Insert the Global Goals using the Goals option with force, frictional force in the X and Y direction.
10. Insert the Surface Goals using the Goals option with force in the X and Y direction.
11. Then use the Mesh option to create a local mesh on the face as shown above and increase the number of refining cells.
12. Run the simulation to obtain the results, stop the simulation when the SG force X reaches it's Goal a green bar shows the results are obtained.
13. Use the Cut plot to create the cut plot in the XY plane as shown above.
14. Use the Goal plot to get the goal plot results as shown above.

Result:

Case 1: 0 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 0 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 0 deg.

This is the velocity cut plot when the angle of attack is 0 deg.

Case 2: 2 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 2 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 2 deg.

This is the velocity cut plot when the angle of attack is 2 deg.

Case 3: 4 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 4 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 4 deg.

This is the velocity cut plot when the angle of attack is 4 deg.

Case 4: 6 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 6 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 6 deg.

This is the velocity cut plot when the angle of attack is 6 deg.

Case 5: 8 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 8 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 8 deg.

This is the velocity cut plot when the angle of attack is 8 deg.

Case 6: 10 deg

This plot describes the pressure acting on the airfoil as the air passes over it when the angle of attack is 10 deg.

These are the results of the surface plot over the airfoil when the angle of attack is 10 deg.

This is the velocity cut plot when the angle of attack is 10 deg.

Conclusion:

It can be observed from the plots and results that with the increase in the angle of attack the velocity and the forces acting on the airfoil also raises.

The Simulation has been successfully run, the necessary results and their corresponding plots are created.

References:

https://en.wikipedia.org/wiki/Airfoil

Project Link:

https://skill-lync.com/projects/flow-over-an-airfoil-141