Flow over an airfoil

Air Flow simulation

Aim: To Create a model of NACA0017 Air foil and to perform a flow simulation over the model to find the Lift and drag forces change for difference angle of rotation of the Airfoil.

Airfoil: Airfoil are structure that are used to produce lift for an aerodynamic structure in aeronautics the airfoil works with the help by producing Drag and a lift force while moving through a medium.

Lift: When Airfoil moves over through medium like fluid and air due to the curve structure of airfoil it produces a perpendicular for over the surface of the airfoil which make the airfoil to get lifted, this perpendicular force is called as lift.

Lift force can be calculated by

FL = CL ½ ρ v2 A

Where,

FL = lifting force (N)

CL = lifting coefficient

ρ = Density of fluid

V = flow velocity (m/s)

A = body area (m2)

Drag: The force exerted over the surface which is parallel to the surface of the airfoil is known as drag force. this force is a resistive force offered by the fluid medium traveling in the opposite direction of motion of the airfoil.

Drag force can be calculated by

Fd = CD ½ ρ v 2 A

Where

Fd = Drag force

CD = Coefficient of Drag

ρ = Density of fluid

V = Speed of the body relative to air

A = Cross-sectional area of the body

NACA0017 air foil:

The NACA0017 is controlled by four digits. The chamfer is 2% of the chord, position of the maximum chamfer is 40% of the chord and thickness is 12% of the chord.

Objective of the project:

• To import the coordinates of airfoil NACA0017 for obtaining the curve.
• To conduct the air flow simulation over the airfoil model at 0,2,4,6,8,10 degrees.
• Set up the global goals to force at X and Y axis.
• Set local goals on the surface of the airfoil with force on X axis to obtain the Drag Force and Force about Y axis to obtain the
• Then compare the Lift at each angle of attack to find the saturation of the stall angle.

Body

• The data file from the website is taken and they are imported into solidworks curve.
• The model is extruded to a length of 0.5 mm
• Then the flow simulation is setup with the working medium as AIR and the initial velocity as 600 m/s.
• The computational mesh is set to 2D at XY plane.
• The local mesh is included at the surface of the airfoil with increased mesh fineness.
• The local and global goals are set.
• The flow simulation is started to calculate.
• To view the result of the flow simulation a cut plot was provide at the middle of the model

Mesh fineness upto 3

Air foil at `0^o` angle of attack

Air foil at `2^o` angle of attack

Air foil at `4^o` angle of attack

Air foil at `6^o` angle of attack

Air foil at `8^o` angle of attack

Air foil at `10^o` angle of attack

Drag force and Lift Comprassion

1. From the above profile and table, we can see that the Drag force and the Lift force increases with increase with Increase in angle of attack.
2. The negative value in the lift force at `0^o` is due to the surface area difference between top and bottom of the Computational area which provides the lift from back part of the airfoil which leads to a negative lift.
3. The Lift value is highest at `10^0` angle of attack where it has the maximum lift force.
4. As the angle of attack increases, the pressure forces developed at the nose of the airfoil gets reduced.
5. And the velocity of the air at the nose increases with increases in the angle of attack due to the curve that lowers air resistance.
6. The stall angle not saturated yet because of the increaseing velocity from `0^0` to `10^o`.

Conclusion: From the flow simulation over the air foil is done and its behavior over different angle of attack is used to calculate the lift and drag force respectively.