A propulsion assembly includes a fan and a fan case system disposed about the fan. The fan case system includes at least one perforated portion including a plurality of holes. The propulsion assembly further includes at least one acoustic panel mounted to the exterior surface of the fan case system coincident with the at least one perforated portion. The at least one acoustic panel includes a core including a plurality of cells extending between a first side of the core and a second side of the core. The at least one acoustic panel further includes a back skin attached to the second side of the core. The first side of the core is in contact with the exterior surface of the fan case system to form a plurality of resonant cavities defined by the plurality of holes, the plurality of cells, and the back skin.

A fan includes a hub and a blade assembly. The hub has a central portion and an extension portion. The extension portion is extended outwardly from a peripheral edge of the central portion. The blade assembly includes a plurality of blades. Each blade has a leading edge, each of the leading edges is an end point of each blade that is most close to the central portion. The blades are disposed around the hub. At least a part of the leading edges of the blades are connected to the extension portion, and distances between a center of the central portion and the leading edges of at least two blades are different. Therefore, the factors of fan and the quality of voice could be enhanced, and the multi-frequencies noise could be avoided during operation.

A compression device includes a centrifugal compressor and a silencer. The centrifugal compressor includes a compressor assembly bolt fastening an inlet side of an inlet guide to a scroll casing. The silencer includes: a first side wall extending in a direction intersecting with a rotational axis of an impeller; an annular second side wall provided between the first side wall and the centrifugal compressor and surrounding the rotational axis; at least one silencer element provided in an ambient-air introduction space formed between the first side wall and the second side wall for guiding an ambient air to the inlet guide; and a silencer assembly bolt extending from the first side wall to the scroll casing in a direction along the rotational axis of the impeller and fastening the first side wall, the second side wall, and the scroll casing.

A compressor (100) comprises a compressor body (10), a pipe (20) connected to the compressor body (10), and an acoustic cover disposed so as to surround the compressor body (10). The acoustic cover (30) has an insertion hole (31) through which the pipe (20) is inserted while being in close contact with the pipe (20), and an inner surface (30A) of the acoustic cover has a shape that traces an outer surface (10A) of the compressor body (10). Due to this configuration, it is possible to reduce the size and the weight of the acoustic cover (30), and by using the acoustic cover (30) with a simpler structure, it is possible to reduce the noise of the compressor (100) of this automobile air conditioning device.

An electric air pump includes a housing, a cover body, an inflation module, and a control module. The housing is provided with a first vent port. The cover body covers the housing, and the cover body is provided with a second vent port. The inflation module is disposed in the housing. The control module is disposed in the housing, and the control module comprises a control circuit board and an air pressure detection unit. The air pressure detection unit is disposed on the control circuit board, and the control circuit board is electrically connected to the inflation module and configured for performing controlling.

A cleaner reduces noise. The cleaner includes a motor, a fan including a number Z of blades and rotatable at a rotational speed N, indicating revolutions per minute, about a rotation axis by the motor, a cover having an inlet located frontward from the fan, and a number V of ribs located in the inlet. The ribs extend in a radial direction from the rotation axis and are arranged in a circumferential direction about the rotation axis. The fan is rotatable to produce noise having a frequency f.sub.NZ of 20,000 Hz or higher, and f.sub.NZ=(m−k×V)×N/60 and m=n×Z+k×V, where n is an order, m is an integer, and k is an integer.

A fan includes a frame member, a fan body, a surrounding plate and a housing unit. The frame member surrounds an axis and defines an accommodating space in which the fan body is disposed. The fan body is rotatable about the axis. The surrounding plate surrounds the frame member and is formed with at least one plate hole extending in a transverse direction transverse to an axial direction of the axis therethrough. The housing unit surrounds the surrounding plate and has a plurality of housing holes extending in the axial direction of the axis therethrough. The housing unit and the surrounding plate cooperatively define a surrounding space therebetween that is surrounded by the housing holes.

A light-emitting fan includes a fan frame, a light-permeable impeller mounted on the fan frame, a first and a second light source assembly. The light-permeable impeller includes a hub and blades. The hub includes a top plate and an annular side plate. The annular side plate is connected to the top plate, the top plate and the annular side plate together form an accommodation space. The annular side plate has an annular side surface facing away from the accommodation space and an inclined incident surface facing away from the annular side surface and non-parallel to the annular side surface. The blades are connected to the annular side surface. The first light source assembly is located in the accommodation space and configured to emit light to the top plate. The second light source assembly is located in the accommodation space and configured to emit light to the inclined incident surface.

A fan with increased heat-removing ability and reduced noise in operation includes a hub, a baffle, a first blade layer, and a second blade layer. The first blade layer includes a plurality of first blades, and the second blade layer includes a plurality of second blades. An orthogonal projection of each of the plurality of first blades on the baffle is located between orthogonal projections of adjacent two of the plurality of second blades on the baffle. A length of the plurality of first blades is greater or less than a length of the plurality of second blades to avoid any resonance. An electronic device including the fan is also disclosed.

A turbofan engine is provided. The turbofan engine includes a fan having a plurality of fan blades; a turbomachine operably coupled to the fan for driving the fan, the turbomachine having a compressor section, a combustion section, and a turbine section in serial flow order and together defining a core air flowpath; a nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and an inlet pre-swirl vane located upstream of the plurality of fan blades and defining a chord, the inlet pre-swirl vane coupled to the nacelle, wherein the inlet pre-swirl vane is angled at a first angle with respect to the radius of the nacelle, and wherein the chord of the inlet pre-swirl vane is angled at a second angle with respect to the longitudinal axis of the nacelle.