Fluid Dynamics—A General Concept
When objects move through fluids there is energy
exchanged between the moving object and the fluid.
If the object moves through the fluid without
disturbance; i.e., passes through by parting
the fluid, then returning the fluid back to its
undisturbed state, there is very little energy
exchanged. Bicambered™ airfoils use gradients
at the back part of the airfoil to improve the
flow of fluid at the back half of the airfoil,
reducing flow separation and reducing turbulence
of fluid adjacent to the surface, the “boundary
layer”.
Less separation of fluid means less energy exchange
and less drag. It also allows for creating more
lift. By preventing fluid from escaping from
the higher pressure surface to the lower pressure
surface, separation and turbulence are reduced,
the pressure difference between the two sides
of the airfoil is increased and there is more
lift.
There are alternative ways to explain fluid
dynamics. One is the once popular Bernoulli principle
that ties air pressure to air speed claiming
that fluid moves faster on one side of the airfoil
than the other. This does not begin to cover
the complexity of fluid flow. It can’t
explain how an airfoil works since the upper
surface of the airfoil isn’t sufficiently
longer than the lower surface to produce the
amount of lift needed to fly. Consider sails
on a sailboat. They are the same length front
and back. Air travels equal distances front and
back so must be traveling at similar speeds,
yet sails produce substantial lift.
It becomes apparent from these examples that
something other than the Bernoulli principle
is needed to explain the behavior of airfoils
and the concepts of lift and drag. This is where
Newton’s laws of motions come in handy.
They can explain the behavior of fluid molecules.
Fluid
Dynamics and Airfoil Motion - Next Page >
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