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[image]. PHYSICAL BACKGROUND. [image]. Bernoulli’s Principle Lift Generation Venturi Theory Equal Transit Theory fallacy Coanda effect Theory Newton’s Laws of Motion Momentum Theory Skipping Stone Theory Lift in Mathematics.
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[Audio] Physical Background Lift Generation Though we don’t always think of it this way, Air is a fluid, just less dense than liquids like water. Objects that are lighter than air are buoyant within it, while heavier objects require an upward force, called Lift, to stay aloft. For planes, this force is mostly generated by the Wings. As for helicopters, it’s generated by rotor blades. But how? Well, wings and Rotor blades are made in the shape of an Airfoil, and airfoils produce lift when a fluid flows over them. Then again, Why and How? While some state that the upward force (Lift) is a result of a differential in pressure between the lower and the upper surface of an airfoil in accordance with Bernoulli’s principle, others see to it a matter of momentum between the airfoil and the moving air compliantly to Newton’s laws of motion. Let’s check out each standpoint! Lift Lift.
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[Audio] Physical Background Bernoulli’s principle Conservation of Energy : The concept of conservation of energy states that : energy cannot be created or destroyed, it can only be transformed. So the amount of energy entering a system is the same that must exit. In fluid dynamics, the “energy” referred to in a is Total Pressure. In a streamline, This energy can be broken down into: Dynamic pressure (the fluid’s kinetic energy more velocity, more kinetic energy); and Static pressure (or simply Pressure energy). These energies will change among themselves, but the Total Pressure energy remains constant inside the system..
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[Audio] Bernouilli’s Principle : As a statement of the law of conservation of energy, Bernoulli’s principle describes the relationship between internal fluid pressure P (static) and its velocity 5 (dynamic). As it applies to Aerodynamics (air being a fluid), Bernoulli's principle states that if there is an increase in air velocity, then there will be a proportional decrease in its pressure. Put otherwise : “the faster the air moves the lower pressure it creates due to the conservation of energy”. This statement, as it is, holds true, however, a misapplication of Bernoulli’s principle and equations would lead to wobbly explanations such as the Venturi theory, or to utterly false hypotheses such as the Equal Transit Time theory. P plus ½ (ρV² )= cst Dynamic Pressure (Kinetic energy) Static Pressure Pressure Velocity.