FLOW OVER AN AIRFOIL
1.AIM :
TO SIMULATE FLOW OVER NACA0017 AIRFOIL FOR DIFFERENT ANGLE OF ATTACKS
2.OBJECTIVE :
- To perform transient flow simulation over NACA0017 airfoil for different angle of attack using Solidworks flow works.
- To obtain and compare lift and drag forces for all angle of attacks.
- To create cut-plot for velocity for all cases.
3.INTRODUCTION :
Flow simulation over an airfoil can be performed through computational fluid dynamics (CFD), a powerful and convenient tool to perform CFD is Solidworks flow simulation.
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate the free stream flow of the fluid, and the interaction of the fluid with surfaces defined by boundary conditions.
In simple words to perform CFD following steps are performed in order:-
- A computational model is made using computer aided designing and the domain of fluid is extracted.
- Further the domain is divided into discrete cells called mesh.
- Next the Boundary conditions are defined, which is specifying the fluid behaviour and properties at all bounding surfaces of the fluid domain.
- Next the calculations are performed and the equations are solved iteratively till the convergence is achieved.
- Finally the analysis and visualization of the calculations performed can be seen.
An airfoil is the cross-sectional shape of a wing or blade which can be used to produce aerodynamic forces when moving through fluid.
The component of force perpendicular to the direction of motion is called lift and the component of force parallel to direction of motion is called drag.
The angle of attack is the angle at which relative wind meets an airfoil. It is the angle formed by the Chord of the airfoil and the direction of the relative wind or the vector representing the relative motion between the aircraft and the atmosphere.
Here in this work the model of NACA0017 airfoil is made using the datafile and flow over the airfoil is simulated using Soildworks flow simulation for angle of attacks 0,2,4,6,8,10.
Click Here to download the NACA0017 airfoil Data file.
Further the lift and drag forces for all angle of attack cases are compared.
4.PROCEDURE :
1)The curve for airfoil is created using data points from the datafile and that curve is converted into sketch and further extruded to make an airfoil.
Airfoil is rotated with repect to origin as per the angle of attack.
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2)Using the wizard option in Soildworks flow simulation a new project is created. The analysis type selected is External and a time dependent analysis is chosen.
3)Further the air is selected as working fluid.
4)The velocity of air (600 m/s) and ambient conditions are entered and the project is created.
5)The analysis done is 2D, therefore the xy plane is selected as computational domain, the domain is expanded in both the directions in such a way that the length of wake region is 10-15 times the chord length and the region ahead airfoil is 5 times the chord length.
6)The surface goals are added to calculate surface force which gives the lift and drag forces.
7)A global mesh is created and a local mesh near the surface is added to give a more refined mesh near surface for better analysis.
8)Finally the simulation is run for different angle of attacks and the drag and lift forces are found.
5.RESULTS :
The cut plot for velocity contour and value for drag and lift forces for different angle of attacks are given below.
CASE 1
Angle of attack = 0 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil is of very negligible quantity because of 0 degrees of angle of attack which lets the air to pass without giving any reaction force on airfoil surface.
The flow seperation region with decreased velocity can be seen from the velocity contour.
CASE 2
Angle of attack = 2 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil has increased drastically when compared to case of 0 degrees of angle of attack, as the angle of attack increases the reaction force on airfoil surface by air increases.
The drag force has increased from significantly compared to the previous case, as with increase in angle of attack the frontal area of airfoil increases which leads to increase in drag force.
The flow seperation region with decreased velocity has increased compared to previous case and can be seen from the velocity contour.
CASE 3
Angle of attack = 4 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil has increased significantly compared to case of 2 degrees of angle of attack, as the angle of attack increases the reaction force on airfoil surface by air increases.
The drag force has increased from significantly compared to the previous case, as with increase in angle of attack the frontal area of airfoil increases which leads to increase in drag force.
The flow seperation region with decreased velocity has increased compared to previous case and can be seen from the velocity contour.
CASE 4
Angle of attack = 6 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil has increased significantly compared to case of 4 degrees of angle of attack, as the angle of attack increases the reaction force on airfoil surface by air increases.
The drag force has increased from significantly compared to the previous case, as with increase in angle of attack the frontal area of airfoil increases which leads to increase in drag force.
The flow seperation region with decreased velocity has increased compared to previous case and can be seen from the velocity contour.
CASE 5
Angle of attack = 8 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil has increased significantly compared to case of 6 degrees of angle of attack, as the angle of attack increases the reaction force on airfoil surface by air increases.
The drag force has increased from significantly compared to the previous case, as with increase in angle of attack the frontal area of airfoil increases which leads to increase in drag force.
The flow seperation region with decreased velocity has increased compared to previous case and can be seen from the velocity contour.
CASE 6
Angle of attack = 10 degrees
Velocity contour
Lift and drag forces
'SG force (X)1' represents drag force and 'SG force (Y)1' represents lift force
The lift force on the airfoil has increased significantly compared to case of 8 degrees of angle of attack, as the angle of attack increases the reaction force on airfoil surface by air increases.
The drag force has increased from significantly compared to the previous case, as with increase in angle of attack the frontal area of airfoil increases which leads to increase in drag force.
The flow seperation region with decreased velocity has increased compared to previous case and can be seen from the velocity contour.
COMPARISON OF LIFT AND DRAG FORCE FOR DIFFERENT ANGLE OF ATTACK
| ANGLE OF ATTACK (DEGREES) | DRAG FORCE (N) | LIFT FORCE (N) |
| 0 | 294.744 | 0.724 |
| 2 | 324.404 | 813.391 |
| 4 | 403.106 | 1601.619 |
| 6 | 539.669 | 2385.186 |
| 8 | 737.597 | 3169.827 |
| 10 | 970.766 | 3932.260 |
With the increase in angle of attack the drag force and lift force also increases, as the frontal area increases with increase in angle of attack it leads to increase in drag force and lift force.
With increase in angle of attack the the lift force increases rapidly, for 0 degrees of angle of attack the lift force negligible.
6.CONCLUSIONS :
The simulation for flow over NACA0017 airfoil for different angle of attack was completed successfully using Solidworks flow simulation.
With the increase in angle of attack the drag force and lift force also increases, as the frontal area increases with increase in angle of attack it leads to increase in drag force and lift force.
For 0 degrees of angle of attack the lift force negligible.
7.REFERENCES :