A centrifugal fan comprises a rotor that has a rotor yoke, an impeller that has a blade and is coupled to the outer periphery of the rotor yoke, a motor that rotates the rotor and a casing that has a suction opening and a discharge opening, and houses the rotor, the impeller, and the motor. The impeller rotating together with the rotor discharges air sucked in through the suction opening to the outside of the casing through the discharge opening. An inner periphery part of the blade on the rotor yoke side extends to the inner periphery side, in such a manner as to overlap with an outer peripheral surface of the rotor yoke in the axial direction of the motor.

Systems and methods are provided for cooling electronics and rear end stator windings in an alternator. The system includes an alternator having a rotor assembly, stator assembly, and dual-sided fan disposed in a housing. The housing includes a drive end, rear end, and sides. The rotor assembly includes drive end and rear end poles. The stator assembly surrounds the poles and includes drive end and rear end stator windings. The dual-sided fan is mounted to the rotor assembly adjacent the rear end poles within the housing. The dual-sided fan includes a separating wall, drive end blade set, and rear end blade set. The drive end blade set extends from a first side of the separating wall and at least partially faces the drive end. The rear end blade set extends from a second side of the separating wall and at least partially faces the rear end.

A centrifugal fan impeller structure includes a hub and a blade body set. The hub has an extension section. The blade body set has multiple blade bodies. The blade bodies outward extend from the extension section of the hub. Each two adjacent blade bodies define therebetween a flow way, an air outlet and an air inlet. The air outlet and the air inlet are respectively positioned at two ends of the flow way in communication with the flow way. The air outlets are arranged at unequal intervals so as to greatly reduce noise in operation.

A centrifugal fan impeller structure includes a hub having multiple blades. The blades extend from a circumference of the hub in a direction away from the hub. Each two adjacent blades define therebetween a flow way, an air outlet and an air inlet. The air outlet and the air inlet are respectively positioned at two ends of the flow way in communication with the flow way. The air outlets are arranged at unequal intervals so as to greatly reduce noise in operation.

A turbofan includes a boss rotatable about an axis, a main plate connected to the boss, a shroud having an intake hole, and a plurality of blades arranged between the main plate and the shroud. An undulating protrusion portion is arranged at a front edge portion of each blade. The undulating protrusion portion includes a plurality of protrusions. The pitches of the plurality of protrusions are formed so as to become smaller as approaching to the main plate side.

Some embodiments of an apparatus and system are described for a volumetric resistance blower. An apparatus may comprise a motor, a rotor comprising a cylindrical foam block, and a casing having one or more inlets arranged in an axial direction of the rotor and one or more outlets arranged in a radial direction of the rotor. Other embodiments are described.

Structures are formed in a shape protruding from a wing surface, and a plurality of riblets are formed in a shape depressed from the wing surface. A first cross section obtained by cutting the structure by a flat face that is parallel to a flow and perpendicularly intersects with the wing surface has an inclined side that extends from a point on the wing surface to a top that is a point apart from the wing surface. An inter-structure flow channel is formed between two adjacent structures among the plurality of structures. The area of a face in one of the two structures and the area of a face in the other structure with which a fluid flowing in the inter-structure flow channel comes into contact are different from each other. Accordingly, peeling of the flow can be suppressed and the frictional resistance of the flow can be decreased.

A compressor rotor, such as a fan, for a gas turbine engine is described which includes alternating at least first and second blade types. The leading edge of the second blade types includes a leading edge tip cutback extending to the blade tip thereof. The leading edge tip cutback of the second blade type defines a chord length at the blade tip of the second blade types that is less than that of the first blades types. The first and second blade types generate different shock patterns when the fan or compressor rotor operates in supersonic flow regimes.

A bladed rotor system for a turbomachine includes a circumferential row of blades mounted on a rotor disc, and includes a plurality of under-platform dampers. Each damper is located between adjacent blade platforms. The plurality of dampers includes a first set of dampers and a second set of dampers. The dampers of the first set are distinguished from the dampers of the second set by a cross-sectional material distribution in the damper that is unique to the respective set. Dampers of the first set and the second set are positioned alternately in a periodic fashion in a circumferential direction, to provide a frequency mistuning to stabilize flutter of the blades.

A fan according to the present invention includes: a main plate fixed to a rotation axis of a driving device; a shroud including an air inlet; and an impeller including n blades between the main plate and the shroud, tip ends of leading edges of the respective blades arranged along a circle around the rotation axis, wherein all of the attachment pitch angles a are different angles, and the blades are arranged so that, in the attachment pitch angles α, attachment pitch angles on both sides of an attachment pitch angle α.sub.m are a combination of other than an attachment pitch angle α.sub.m−1, which is the next smallest angle in order of magnitude of angle to the attachment pitch angle α.sub.m, and an attachment pitch angle α.sub.m+1, which is the next largest angle in order of magnitude of angle, to the attachment pitch angle α.sub.m.