Aerodynamics of the Blade: How Airfoils Define axial industrial fans Fan Performance The efficiency and performance of any ac axial fans fan are fundamentally dictated by the complex aerodynamics of its blades[4]. These blades are not simple paddles, but meticulously engineered airfoils, sharing the same principles as aircraft wings[4]. The three critical aerodynamic design parameters are the Blade Profile (Aerofoil Shape), the Pitch Angle, and the use of Sweep and Skew[4][15]. The aerofoil profile determines the ratio of lift (the desired propulsive force) to drag (the resistance)[5]. A well-designed profile minimizes turbulence and maximizes the pressure differential, directly increasing energy efficiency[4]. Secondly, the Pitch Angle, which is the angle between the blade chord line and the plane of rotation, controls the "aggressiveness" of the air movement[4][5].