ABSTRACT

Aerodynamic flows are encountered when one is dealing with any aspect of aeronautical engineering. Physical principles that govern aerodynamic flows are based on the conservation of mass, momentum and energy. Just as Euler’s equations of motion are derived from Newton’s laws of motion in classical mechanics, secondary laws governing the dynamics of rotational flows can be derived from the fundamental physical principles. The flows around aerofoils are the simplest examples of aerodynamic flows. In aerofoil theory, it is possible to idealise the flow by ignoring the influence of the compressibility of the fluid medium. When compressibility is included, one needs to consider three distinct cases: subsonic flow when the flow velocity is well below the speed of sound or pressure disturbances in the flow, transonic flow when the flow velocity is in the vicinity of the speed of sound and supersonic flow when the flow velocity is well above the speed of sound. Furthermore, the viscous forces which result in friction at the boundaries play a key role in aerodynamic flows. In this chapter, we review the basic principles governing aerodynamic flows, the influence of compressibility and viscosity, the definition of the standard properties of the atmosphere, the flow around an aerofoil, the generation of lift, drag and moment over an aerofoil and the basic properties of aerofoil aerodynamics.