A blower fan for preventing noise generated from blades and a peripheral interference object is provided, the blower fan including a cylindrical hub, a plurality of blades disposed to be spaced apart an asymmetric distance from one another about the hub, and a balancer connected to the hub to balance the blades.

An impeller includes Z blades, where Z is an integer equal to 5 or more, arranged in a circumferential direction of the impeller and extending radially, pitch angles between adjacent blades being all different. In terms of an arbitrary pitch angle θ, when a pitch angle α1 adjacent to the pitch angle θ, and a pitch angle α2 adjacent to the pitch angle θ, different from the pitch angle α1, satisfy a relation, α1<α2, a pitch angle β1 different from the pitch angle θ adjacent to the pitch angle α1 and a pitch angle β2 adjacent to the pitch angle β2, different from the pitch angle θ, satisfy a relation, β2<β1.

An aircraft comprising a pair of ducted thrusters. Each of the ducted thrusters comprises a duct surrounding a rotor assembly with a rotor hub having a plurality of rotor blades extending therefrom, wherein the plurality of rotor blades have a modulated angular distribution about a central longitudinal axis of the duct. Each of the ducted thrusters further comprises a stator assembly having a stator hub with a plurality of stator vanes extending from the stator hub to an interior surface of the duct, wherein each of the plurality of the stator vanes are angularly modulated around the stator hub such that angular spacing between pairs of adjacent vanes of the plurality of stator vanes varies for each pair of the adjacent vanes.

A fan for cooling an electronic device is described, wherein the fan can include an enclosure and a motor secured within the enclosure. The fan can also include an impeller to be turned by the motor, the impeller having a plurality of blades, wherein an angular spacing of the blades results in an audio spread-spectrum within a range of audio frequencies. In some examples, an arrangement of the blades has a center of mass below a threshold, and the angular spacing of the blades and a blade pass frequency (BPF) results in sound that is distributed in the range of audio frequencies.

An impeller includes a hub and blades. In radial direction, an upper surface of the blade near the outer edge includes a groove structure, a lower surface of the blade relating to the groove structure includes a peak structure, the lower surface of the blade includes a recess structure aside the trailing edge or the leading edge. The recess structure is connected to the peak structure. The blade has at least five airfoils from the inner edge to the outer edge. The blade is defined by continuously connecting the at least five airfoils at different sections in sequence so as to form the groove structure and the peak structure respectively on the upper surface and the lower surface. The groove structure and the peak structure are aside the outer edge of the blade.

A fan has an impeller (20) that is equipped with blades (26, 28, 30, 32, 34; 58). The blades are configured so that the blade loading of individual blades differs during operation. As a result of this variable blade loading, the frequencies associated with the blade-passing noise (BPF) of the fan can be distributed over a broader frequency spectrum, and thus have a less obtrusive effect.

An aircraft comprising a pair of ducted thrusters. Each of the ducted thrusters comprises a duct surrounding a rotor assembly with a rotor hub having a plurality of rotor blades extending therefrom, wherein the plurality of rotor blades have a modulated angular distribution about a central longitudinal axis of the duct. Each of the ducted thrusters further comprises a stator assembly having a stator hub with a plurality of stator vanes extending from the stator hub to an interior surface of the duct, wherein each of the plurality of the stator vanes are angularly modulated around the stator hub such that angular spacing between pairs of adjacent vanes of the plurality of stator vanes varies for each pair of the adjacent vanes.

Blades (20a to 20c) of a propeller fan (10) have different circumferential pitches 1, 2, and 3. The blades (20a to 20c) have different masses so that the center of gravity of the propeller fan (10) is positioned on a rotational center axis (11) of the propeller fan (10). Blade body portions (42c) of the blades (20a to 20c) have different thicknesses. In contrast, camber lines of the blades (20a to 20c) in blade cross section have the same shape, projections of the blades (20a to 20c) on a plane perpendicular to the rotational center axis (11) of the propeller fan (10) have the same shape, and leading edge portions (41a to 41c) of the blades (20a to 20c) have the same shape. As a result, a propeller fan (10) having reduced noise and vibrations can be achieved.

A centrifugal fan is disclosed. The centrifugal fan includes a housing; and a fan wheel, disposed in the housing, the fan wheel including: a fan hub; a plurality of inner fan blades, each of the inner fan blades includes a first contact surface and a second contact surface, the first contact surfaces are connected to the fan hub respectively; a plurality of connection structures, each of the connections structure includes a first side and a second side; and a plurality of outer fan blades, each of the outer fan blades includes a first end and a second end; wherein the second contact surfaces are connected to the first sides respectively, the first ends are connected to the second sides respectively.

An axial fan comprising a hub and a plurality of blades extending from a periphery of the hub. Each of the blades has a thickness which varies from a leading edge to a trailing edge and from a root to a tip. The blades are unevenly spaced around the periphery of the hub in a pattern which is not balanced. The fan is balanced by variance in blade thickness among the plurality of blades.