Project

FLOW OVER AN AIRFOIL

PPugazhendhi Gopal23 Jun 2020

AIM

To model a flow over a NACA0017 airfoil using Soildworks.

OBJECTIVES

To compare the lift force and drag force of an airfoil for different angle of attacks.

THEORY

The NACA airfoils are airfoils shapes of an aircraft wings developed by National Advisory Committee for Aeronautics. The shapes of an airfoil are described by a series of digit followed by the word NACA. There are different types of series of NACA airfoil. In this project, four-digit series is used.

FOUR DIGIT SERIES

The NACA four-digit section defines the profile by

First digit describing the maximum chamber as a percentage of chord.
Second digit describing the distance of maximum chamber from the airfoil leading edge in tenths of the chord.
Last two digits describing maximum thickness of the airfoil as a percentage of the chord.

For example, the NACA2412 has a maximum chamber of 2% located 0.4 chords from the leading edge with a maximum thickness of 12% of the chord.

In this project we have used NACA0017. The 00 indicates that it has no chamber. The 17 indicates that the airfoil has a maximum thickness of 17% of the chord.

CHORD

In aerodynamics, chord is a line that extends from the leading edge to the trailing edge of an airfoil. The chord is a basic reference axis for geometric or aerodynamic property of an airfoil.

CHORD LENGTH

The chord length is the distance between the trailing edge and a point where the chord intersects with the leading edge.

LEADING EDGE

The leading edge of an airfoil surface such as a wing is a foremost edge and therefor the part which meets the oncoming air.

TRAILING EDGE

The trailing edge of an aerodynamic surface such as wing is the rear edge where the airflow separated by the leading edge meets. Essential flight control surfaces are attached here to control the direction of the departing air flow and exert a controlling force on an aircraft.

ANGLE OF ATTACK

Angle of attack is the angle between the chord line of an airfoil and the vector representing the relative motion between the body and the fluid through which it is moving.

LIFT FORCE AND DRAG FORCE

Any fluid flowing around the surface of the object exerts a force on the object. Lift force is a component of force that is perpendicular to the oncoming flow direction. In contrast, the drag force acts in parallel to the flow direction. Drag force depends on the velocity.

PROCEDURE

The co-ordinates for NACA0017 is imported to Soildworks using Insert curve option. MKS unit system is used in this process.
Suitable plane is selected and Convert Entities is used to for further sketching. The tail end of the curve is closed using the line command to make it has a closed sketch.
The curve can be rotated using the Rotate entities command. Select the entities to rotate and specify the centre of rotation along with the degree to which the entities must rotate. This procedure can be used to rotate the curve for different degrees.
Extrude the surface to certain width and save the drawing.

The following are the 3D model of airfoil for various degree of angle of attack

0-degree Angle of Attack

2-degree Angle of Attack

4-degree Angle of Attack

6-degree Angle of Attack

8-degree Angle of Attack

10-degree Angle of Attack

FLOW STIMULATION SETUP

Flow stimulation can be enabled by selecting Soildworks Add-Ins.
Click on the Wizard icon to create a new project.
Specify the project name and click Next.
In Analysis type select External Flow.
Click on time dependent stimulation. Stimulation time of 5 seconds and Time of step as 1 second and click Next.
In Initial wall conditions specify the velocity in the X-direction as 600 and click Finish.
In Computational domain select 2D stimulation and XY Plane.
The inlet boundary should be 5 times the chord length from the leading edge and the distance between the trailing edge and outlet boundary should be 10-15 times the chord length.
Specify the Global goals and Surface Goals by right clicking on Goals and select force as an input parameter.
Click on global mesh and specify the initial level of mesh. Create a local mesh around the top surface of the airfoil for a better refinement.
Run the stimulation.

The following are the results obtained for various degrees of angle of attacks.

0-degree Angle of attack

Velocity Profile

Pressure profile

Lift force and Drag force

2-degree Angle of attack

Pressure profile

Lift force and Drag force

4-degree Angle of attack

Velocity profile

Pressure profile

Lift force and Drag force

6-degree Angle of attack

Velocity profile

Pressure profile

Lift force and Drag force

8-degree Angle of attack

Velocity Profile

Pressure profile

Lift force and Drag force

10-degree Angle of attack

Velocity profile

Pressure profile

Lift force and Drag force

The relationship between angle of attack and lift force and drag force is shown below

Angle of Attack (degree)	Drag force (N)	Lift force (N)
0	151.898	0.846
2	167.064	412.379
4	208.039	822.001
6	278.996	1235.839
8	379.346	1629.392
10	507.478	2036.098