Patent ID: 6991426
Filing Date: 2006-01-31
Classification: B63H,F01D,F04D,F05B,F05D,Y02T

Abstract:
1. A variable pitch fan, particularly for propulsion, of a type comprising a rotor and at least two stages of stator blades positioned upstream and downstream of said rotor, wherein the rotor blades are of a variable pitch type and have a sinusoidal shape, obtained by locating some pressure centers of the blade airfoils upstream and other pressure centers downstream of a variable pitch rotation axis, so that torques, which are generated by the aerodynamic forces, balance each other, thus allowing use of a low power input to activate the variable pitch; the airfoils on the rotor blade hub and end are disposed so that the axis coincides with a center line of the rotor blade chord, while the other airfoils are disposed so that, under all circumstances, resulting torque changes within a minimum value range, so that a line that joins the centers of all the blade airfoils, has a sinusoidal path.