Abstract: The invention relates to a blade assembly 30 for a large dimension axial fan 32 having a rotation axis X. The blade assembly of the invention comprises: a root structure 34 intended to mechanically connect the blade assembly to a hub 36; a blade, wherein at least one portion of the blade has a composite airfoil 46 comprising a fore semi-airfoil 48 and an aft flap 50, wherein: the semi-airfoil is intended to be assembled at a predefined pitch angle ?c with respect to the hub 36 by means of the root structure; the flap 50 is mounted on the blade such that it can be fixed in a position comprised between a maximum deflection position and a minimum deflection position with respect to the pitch angle ?c; and between the fore semi-airfoil and the aft flap a channel 54 is defined suitable for allowing a fluid flow from the face v to the back d of the composite airfoil. The invention further relates to a fan comprising a plurality of blades.

Abstract: A ducted axial fan. The fan includes a rotor rotatable around an axis X and having a plurality of blades, and a duct suitable for defining a circular section channel developing in an axial direction around the rotor. The duct includes an annular seat circumferentially extending around the rotor, and the blade tips are at least partially received in the annular seat of the duct.

Abstract: Today the low noise blades and especially the super low noise blades for large diameter axial fans which are employed in the big cooling machines and cooling plants are so costly and are requiring so many extra costs on the other related equipment, that the noise pollution abatement can increase the whole cooling apparatus cost by up to a 35%. This invention, provides a new technology to make low noise fans able to transform any common blade into a low noise or very low noise at very low cost, preserving the same high efficiency and tip speed, as opposite to all the other low noise blades at actual status of art. As the fans for the big cooling apparatus are generally their main noise source, this invention will offer the opportunity to dramatically reduce the noise pollution produced by big cooling machines and cooling plants.

Abstract: Today the low noise blades and especially the super low noise blades for large diameter axial fans which are employed in the big cooling machines and cooling plants are so costly and are requiring so many extra costs on the other related equipment, that the noise pollution abatement can increase the whole cooling apparatus cost by up to a 35%. This invention, provides a new technology to make low noise fans able to transform any common blade into a low noise or very low noise at very low cost, preserving the same high efficiency and tip speed, as opposite to all the other low noise blades at actual status of art. As the fans for the big cooling apparatus are generally their main noise source, this invention will offer the opportunity to dramatically reduce the noise pollution produced by big cooling machines and cooling plants.

Abstract: A ducted axial fan. The fan includes a rotor rotatable around an axis X and having a plurality of blades, and a duct suitable for defining a circular section channel developing in an axial direction around the rotor. The duct includes an annular seat circumferentially extending around the rotor, and the blade tips are at least partially received in the annular seat of the duct.

Abstract: A blade for an industrial axial fan including an attachment and an airfoil having a longitudinal axis, the attachment connecting the airfoil to a hub, wherein the attachment has a stiffness and a stiffness distribution that allows the attachment to deform in a way to have at least an inflection point along the longitudinal axis during the operation of the axial fan. The attachment includes a first part for connection to the hub and a second part for connection to a proximal end of the airfoil. The blade further includes a weight fixed at a distal end of the airfoil. The attachment has a decreasing stiffness along its longitudinal direction from the first part to the second part so that during the operation of the axial fan, the attachment deforms and includes the inflection point to thereby induce the blade to vibrate according to a second vibrating mode.