Flow over an airfoil

AIR FOIL:

An airfoil or aerofoil is the cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine), or sail. An airfoil-shaped body moving through a fluid produces an aerodynamic force.

ANGLE OF ATTACK IN AIRFOIL:

The Angle of Attack 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 between the chord line and the flight direction is called the angle of attack and has a large effect on the lift generated by a wing. The nose of the airplane rises, increasing the angle of attack and producing the increased lift needed for take-off.

OBJECTIVE:

• To analyze the flow for NACA-0017 airfoil at various angles of attack and also to compare the lift and drag force.
• To perform the Flow Simulation at various angles of attack from 0° to 10° with an interval of 2° i.e. 0, 2, 4, 6, 8, 10°
• Also to perform Velocity distributions over NACA-0017 airfoil for different angles of attack.
• To plot and compare the Drag Force and Lift Force.

Data File: NACA 0017

PROCEDURE:

STEPS:

• An Airfoil is been created using the provided Data or NACA-0017.
• Initially, the Airfoil is extruded at 0 degrees.
• In the Flow simulation tab, inside the wizard, the Units, Analysis Type, Inlet Velocity, Time-dependent are provided as given above in the table.
• Then Computational domain is inserted in 2D. Then the computational domain is expanded along both X & Y direction in such a way that the length after the region should be 5 times the length ahead of the region.
• The local mesh is provided on the surface of the airfoil and it is refined at 3.
• By inserting the goal plots in surface force X & surface force in the Y direction.
• Running the simulation results in previewing the flow over the airfoil.
• By using the cut plot in results, the velocity contour is previewed and saved.
• The goal plots are resulted in drag force and lift force.
• Then the process is repeated for different angles up to 10 degrees in the airfoil.

3D MODEL:

The airfoil geometry is created using the provided NACA-0017 data by inserting the curve points in XYZ and sketch is done and then it is extruded up to 0.4m using SOLIDWORKS.

Sketch part of Airfoil:

Extruded part of Airfoil:

BOUNDARY CONDITIONS AND VALUES:

Here Flow around an airfoil at various angles of attack (0, 2, 4, 6, 8, 10 degrees) are taken by the boundary condition and values that are provided below:

Input Conditions	Values
Analysis Type	External Flow
Fluids	Air
Units	SI units
Inlet Velocity	600 m/s
Chord Length	1m
Density	1.225 kg/m^3
Time-Dependent	Total analysis time: 5s Output Time step: 1s

RESULTS:

Here, integrated force along the x-axis is taken as Drag force and integrated force along the y-axis is taken as Lift force.

CASE 1: Angle of attack at 0°

Drag force and Lift force

• Drag Force: 602.271 N
• Lift Force: -0.458 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

CASE 2: Angle of attack 2°

Drag force and Lift force

• Drag Force: 666.024 N
• Lift Force: 1670.816 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

CASE 3: Angle of attack 4°

Drag force and Lift force

• Drag Force: 825.801 N
• Lift Force: 3287.914 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

CASE 4: Angle of attack 6°

Drag force and Lift force

• Drag Force: 1106.065 N
• Lift Force: 4888.547 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

CASE 5: Angle of attack 8°

Drag force and Lift force

• Drag Force: 1509.401 N
• Lift Force: 6488.488 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

CASE 6: Angle of attack 10°

Drag force and Lift force

• Drag Force: 1990.68 N
• Lift Force: 8079.051 N

Cut Plot:

Summary:

Drag Force Plot:

Lift Force Plot:

COMPARISION STUDY:

Degree	Avg Drag Force	Avg Lift Force
0	602.271	-0.458
2	666.024	1670.816
4	825.801	3287.914
6	1106.065	4888.547
8	1509.401	6488.488
10	1990.68	8079.051

Comparison of Avg Drag Force:

Comparison of Avg Lift Force:

Drag force vs Lift Force:

CONCLUSION:

Generally, an increase in the angle of attack results in an increase in both lift and induced drag, up to a point. Too high an angle of attack and the airflow across the upper surface of the aerofoil becomes detached, resulting in a loss of lift, otherwise known as a Stall.

Here the following was observed during the above study process:

1. As the angle increases, the drag force initially increases gradually, and then the quadratic line plot was obtained.
2. Also, the constant value for drag and lift force was achieved in earlier iterations as the angle of attack increases.
3. For the various angles of attacks, lift force was obtained as a linear curve without any deviations.
4. The drag is nearly constant at small angles (+/- 5 degrees) for the airfoil
5. The increased frontal and increased boundary layer thickness causes the drag to rise as the angle increases above 5 degrees.

Thus the flow simulation of NACA-0017 airfoil has been performed and the drag force and lift force plots have resulted.