How Does Bernoulli's' Principle Relate
to an Aircraft Wing?
Bernoulli stated in part that “the internal pressure of a fluid (liquid or gas) decreases at points where the speed of the fluid increases.” In other words, high speed flow is associated with low pressure, and low speed flow with high pressure.
This principle is made apparent by changes in pressure of fluid flowing within a pipe where the inside diameter of the pipe decreases, similar to a venturi tube. In the wide section of the gradually narrowing pipe the fluid flows at a lower speed, producing a higher pressure. As the pipe narrows it still contains the same amount of fluid, but because the passageway is constricted the fluid flows at a higher speed producing a lower pressure.
This principle is also applicable to an aircraft wing, since it is designed and constructed with a curve. Lift is the upward force created by an airfoil when it is moved through the air. Although lift may be exerted to some extent by many external parts of the aircraft, there are three principal airfoils on an aircraft the wing, propeller, and horizontal tail surfaces.
When air flows along the upper wing surface it travels a greater distance in the same period of time than the airflow along the lower wing surface. Therefore, as established by Bernoulli's principle, the pressure above the wing is less than it is below the wing, generating a lift force over the upper curved surface of the wing in the direction of the low pressure.