Flow over an airfoil
AIM : To model the flow over an airfoil for various angle of attacks.
OBJECTIVES :
- To model the flow over an airfoil which can be obtained from from the below.
- To compare the lift and drag forces for the angle of attacks 0,2,4,6,8,10 degrees.
Airfoil is defined as the cross-section of a body that is placed in an airstream in order to generate useful aerodynamic force.
Angle of attack[AOA] 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.
AIR FOIL GEOMETRY:
Intial Curve formed with the given NACA data;
After Extrusion;
With Mesh;
CONDITIONS:
The problem consists of flow around an airfoil at various angles of attack (0, 2, 4, 6, 8, 10 degrees).
External Flow
Fluid: AIR
Time Dependent: Total Analysis Time - 5 s
Output Time Step - 1 s
Density: 1.225 kg/m^3
Inlet Velocity: 600 m/s
Chord Length: 0.2 m
PROCEDURE:
- An airfoil is created by using convert entities then line command.
- For the different angle of attacks rotate entities is used.
- The airfoil is extruded to 0.5 mm. Now save the file.
- The flow simulation is created using the wizard menu.
- The analysis type is selected as external. Time-dependent is selected.
- Total analysis time is selected as 5 sec and output time is 1sec.
- The fluid is selected as air and velocity parameter over X-direction is selected as 600m/s and then click finish.
- Now a computational domain is created by using the 2D option.
- The computational domain is expanded along both y-directions and x-direction in such a way that the length after the wake region should be 5 times the length ahead of wake region.
- The Global mesh is defined and the local mesh is defined by selecting the surface. It is refined up to a level of 3.
- The goals option is selected then force x and force y selected after selecting the surface.
- Run the simulation.
- Now a cut plot is made along x-direction and velocity over the airfoil is selected.
- Color refining is given 200.
- A goal plot is plotted between drag force along the x-direction and lift along the y-axis.
- The above procedure is followed for different attack angles and the following results are used to plot the necessary graphs.
- Geometric Modelling -
- At first, the coordinates of airfoil is imported into Solidworks through insert curve options and in a suitable plane its converted into an entity for further sketching. The tail section of the airfoil is not closed so a line is drawn between the two point of tail to make it a closed sketch. For simulation for different angle of attacks, it can be rotated about a reference point by providing angle of rotation. Then it is extruded to a certain width.
- For `0⁰` angle of attack -
- For `2⁰` angle of attack -
- For `4⁰` angle of attack -
- For `6⁰` angle of attack -
- For `8⁰` angle of attack -
- For `10⁰` angle of attack -
- Flow Simulation Setup -
- After modelling, Flow Simulation was setup and following input conditions are given,
- Analysis type: External and Time-Dependent with Simulation Time of 5 seconds and Time Step of 1 second,
- Type of fluid: Air,
- Type of flow: Laminar & Turbulent,
- Wall Condition: Adiabatic Wall with 0 micro-meter roughness,
- Initial Condition: Pressure (101325 Pa), Temperature (293.2K), Velocity x-direction (600 m/s),
- Global goals and surface goals were given for forces in x and y directions. A local mesh was inserted for the top surface of airfoil for a much refinement around it.
- Simulation Results :
- For `0⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Drag Force;
Lift Force;
- For `2⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Graphs:
Drag Force;
Lift Force;
- For `4⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Graphs:
Drag Force;
Lift Force;
- For `6⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Graphs:
Drag Force;
Lift Force;
- For `8⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Graphs:
Drag Force;
Lift Force;
- For `10⁰` angle of attack -
Drag Force – Surface Goal Force (X)
Lift Force – Surface Goal Force (Y)
- Velocity Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
- Pressure Contour - In order to generate a contour, a cut plot was made in the front plane parallel to the cross-section of the airfoil and at the mid length.
Graphs:
Drag Force;
Lift Force;
Comparing Drag force vs Lift Force:
To compare the characteristics of the drag and lift force the following graph is prepared.
CONCLUSIONS :
| Angle of attack (degrees) | Average Drag Force (N) | Average Lift Force (N) | Maximum Velocity (m/sec) | Minimum Velocity (m/sec) | Maximum Pressure (Pa) | Minimum Pressure (Pa) |
| 0 | 150.551187010265 | -0.0133613331935715 | 626.29 | 0 | 465774.39 | 76314.06 |
| 2 | 166.663950596008 | 416.294882013918 | 647.35 | 0 | 564401.54 | 69029.90 |
| 4 | 207.157428288354 | 821.358145369852 | 654.16 | 0 | 511131.21 | 64946.28 |
| 6 | 275.846241139197 | 1224.95123743898 | 668.95 | 0 | 574147.36 | 59018.80 |
| 8 | 377.200757572 | 1621.27586891698 | 680.22 | 0 | 625285.54 | 53017.57 |
| 10 | 498.883526961526 | 2026.31305034282 | 694.80 | 0 | 467914.04 |
With the help of SOLIDWORKS Flow Simulation, successful analysis of the NACA-0017 airfoil has been carried at various angles of attack (0, 2, 4, 6, 8, 10 degrees) and following observation has been made.
- With the increase in angle of attack, the number of iterations required to give the result get reduced.
- With the increase in angle of attack, Drag force increases slowly and lift force increases rapidly.
- With the increase in angle of attack, the velocity of air over the airfoil increased.
Sample data below in the box