- The Kutta condition states that the circulation around an airfoil is just the right value to ensure that the flow smoothly leaves the trailing edge. How does nature generate this circulation?
- Does it come from nowhere, or is circulation somehow conserved over the whole flow field?
- As the flow over the airfoil is started, the large velocity gradients of the sharp trailing edge result in the formation of a region of intense vorticity which ... forms the starting vortex.
- The starting vortex builds up to just the right strength such that the equal and opposite cirrculation around the airfoil leads to a smooth flow from the trailing edge.
fredag 27 juli 2012
John D Anderson's Fundamentals of Aerodynamics
The generation of lift of a wing is presented as follows in Chapter 4 Incompressible Flow over Airfoils:
This is the classical Kutta-Zhukovsky Circulation Theory (CT), which thus still 100 years after its conception forms the basis of aerodynamical theory of flight.
We show in New Theory of Flight that CT does not describe the actual generation of lift of a wing. We do this by solving the Navier-Stokes equations describing the flow around the airfoil and inspecting the solutions to see that the aerodynamics described by Anderson is not actual physics, only fictitious physics invented by incorrect mathematics and physics.