Flow over an airfoil

Aim: To model the flow over a NACA0017 air foil. 

Description: COMPUTATIONAL FLUID DYNAMICS: The field of study devoted to solution of the equations of fluid flow through use of a computer (or, more recently, several computers working in parallel). Modern engineers apply both experimental and CFD analyses, and the two complement each other. 

External flow: Sometimes a fluid moves over a stationary body (such as the wind blowing over a building), and other times a body moves through a quiescent fluid (such as a car moving through air). These two seemingly different processes are equivalent to each other; what matters is the relative motion between the fluid and the body. Such motions are conveniently analyzed by fixing the coordinate system on the body and are referred to as flow over bodies or external flow. 

Drag: The force a flowing fluid exerts on a body in the flow direction is called drag. 

Flow Separation: A fluid climbs the uphill portion of the curved surface with no problem, but it has difficulty remaining attached to the surface on the downhill side. At sufficiently high velocities, the fluid stream detaches itself from the surface of the body. This is called flow separation. 

Figure 1: Flow separation over a backward facing step along a wall. 

When a fluid separates from a body, it forms a separated region between the body and the fluid stream. This low-pressure region behind the body where recirculating and backflows occur is called the separated region. 

Airfoil:

Figure 2: Definition of various terms associated with an airfoil. 

• Span: The distance between the two ends of a wing or airfoil is called the wingspan or just the span. 
• Angle of attack: The angle the incoming fluid stream makes with the chord (the line that connects the nose and the end) of the airfoil. 

Figure 3: For airfoils, the contribution of viscous effects to lift is usually negligible since wall shear is parallel to the surfaces and thus nearly normal to the direction of lift. 

Objective: For the angle of attacks 0,2,4,6,8,10 compare the lift and drag forces. 

Figure 4: Flow of the project. 

Steps Followed: 

• A Naca airfoil created using the curve file provided by skill Lync. 
• Flow simulation is opened. 
• Then some initial conditions are provided such Fluid type, thermodynamic parameters, analysis type. 
• Flow domain is setup. 
• Boundary conditions are provided. 

• Discretisation is done(meshing). 
• For results the plots are created at required positions are created the cut plots. 
• Then flow simulation is ran. 
• Desired outputs are saved. 
• Same process is followed for all cases. 

Results: 

Case 1: 0-degree angle of attack

Figure 5: Pressure plot 

Figure 6: Velocity Plot

                Figure 7: Drag Force  

Figure 8: Lift Force 

Case 2: 2-degree angle of attack 

Figure: Velocity Plot  

Figure 9: Pressure plot 

Figure 10: Drag Force 

Figure 18: Drag Force 

Figure 19: Lift Force

Case 5: 8-degree angle of attack 

Figure 20: Velocity Plot 

Figure 21: Pressure plot 

Figure 22: Drag Force 

Figure 23: Lift Force 

Case 5: 8-degree angle of attack 

Figure 24: Velocity Plot 

Figure 25: Pressure plot 

Figure 26: Drag Force 

Figure 27: Lift Force 

Case 6: 10-degree angle of attack 

Figure 28: Velocity Plot 

Figure 29: Pressure plot 

Figure 30: Lift Force 

Figure 31: Drag Force 

Conclusions: 

Figure 32: The variation of the lift and drag force with angle of attack. 

• The lift and drag force increases with the angle of attack until the airfoil stalls.