Effect of angle of attack on flow field and body forces

This quasi-steady state animation shows a Van de Vooren 15% thickness ratio symmetric aerofoil cycling sinusoidally through a +-15 deg angle of attack range. The first animation shows the streamlines and pressure field, the second shows the normal forces on the aerofoil, the third the lift component, and the fourth the pressure drag c...omponent (which integrates to zero in a potential flow). The purpose of this animation was to reveal how the majority of the lift force comes from the upper surface near the leading edge. Thus rather than being held in the sky by sitting on a cushion of high pressure, it is more the case that you are being suspended by imaginary strings connected to the top of the wing!

In reality, pitching the aerofoil as was done in this animation would result in vortex shedding at the trailing edge due to the change in circulation with angle of attack. This occurs to satisfy the Kelvin condition of constant total circulation enclosing body and wake for all time. Such a code is in development and an unsteady flow animation of a pitching aerofoil with wake roll-up is coming soon.... ;-]

Category:

Education

Tags:

• airfoil
• aerofoil
• panel method
• inviscid
• fluid dynamics
• potential flow
• Laplace
• incompressible
• wing
• lift
• Kutta condition
• circulation
• vortex panel
• angle of attack