A fan includes a frame, an impeller and a motor. The impeller includes a hub, a plurality of blades, first air-guiding plates and second air-guiding plates. The hub has a tapered shape. A width of the hub gradually increases along a direction from a top portion of the hub to a bottom portion of the hub. The hub has at least an air vent. The blades are disposed around an outer periphery of the hub. The first air-guiding plates and the second air-guiding plates are disposed around an inner periphery of the hub. The first air-guiding plates are arranged between two of the second air-guiding plates in staggered. The second air-guiding plates are arranged between two of the first air-guiding plates in staggered. The first air-guiding plates and the second air-guiding plates have different thicknesses, heights or shapes.

An aircraft propulsion system includes a propulsive fan assembly configured for assembly into an aircraft structure, the propulsive fan assembly that includes a fan rotatable about a fan axis, an inlet duct assembly disposed within the aircraft fuselage, the inlet duct assembly that includes an upper inlet duct with an upper inlet opening and a lower inlet duct with a lower inlet opening. The upper inlet duct and the lower inlet duct merge into a common inlet duct forward of the propulsive fan assembly, and an outlet duct is disposed aft of the propulsive fan assembly.

A ventilation unit (1) is formed by at least one fan (2), a heat exchanger, axially spaced from the fan (2), and a housing (3). The housing (3) has a first housing section (4), with a constant flow cross-section, where the heat exchanger is arranged. A second housing section (5) adjoins the first section (4) in the axial flow direction. The fan (2) is arranged on the second housing section (5) in the axial flow direction. During operation, the fan conveys air through the heat exchanger, arranged in the first housing section (4), and through the second housing section (5). The flow cross-section of the second housing section (5) is reduced in the flow direction from the first housing section (4) to the fan (2) by an adaptation to the form of housing wall sections (6, 6′) of the second housing section (5).

The utility model relates to a noise reduction device for an outlet side of a fan, and a heat exchange system including the noise reduction device. The noise reduction device includes: a connecting portion configured to be connected with at least a part of the air duct cover, and form an accommodation space communicating with an airflow on the outlet side via at least one of the through holes; and at least one first chamber and/or at least one second chamber, the first chamber being located in the accommodation space and filled with a sound-absorbing material, and the second chamber being located in the accommodation space and configured as a resonant noise-reduction cavity. The utility model is easy to manufacture, install and maintain, the noise reduction effect is obvious, and therefore the utility model has significant practicability.

A diffuser arranged at the downstream side of a blower, the diffuser including a conical diffuser shroud with a back draft damping butterfly valve arranged in the diffuser opening, and where the butterfly valve includes two doors both being attached to the diffuser shroud via a hinge arrangement adapted for allowing each of the two doors to rotate between a closed and an open position about the hinge axes extending between opposite sides of the diffuser shroud and where the doors are shaped so that they together substantially close the diffuser opening when they are in their closed position, and wherein each hinge axis intersects the diffuser shroud at a position closer to the upstream side at one side than on the opposite side of the diffuser shroud.

A fan silencing system includes a fan, and an acoustic resonance structure, in which the acoustic resonance structure is disposed in a near field region of a sound generated by the fan.

An outdoor unit of an air conditioner includes a housing including an outlet, a fan disposed inside the housing, and a guide guiding air flowing by the fan, wherein the guide includes an inflow portion provided to guide air introduced into the housing to the fan and a diffuser extending from the inflow portion to guide air passing through the fan to the outlet. The inflow portion includes a duct connected to the diffuser, a bell mouth disposed on an upstream side further than the duct and configured such that a width of an inlet end of the bell mouth is wider than a width of an outlet end of the bell mouth, and a guide vane formed on the bell mouth and configured to guide air introduced into the fan.

An air guide arrangement, for a ventilation system, has a housing forming a flow channel with a fan arranged in the flow channel to generate an airflow through the housing. A flow guide device is arranged in the flow channels. The flow guide device is axially connected downstream of the fan on the outflow side and directly influences the airflow generated by the fan. The flow guide device has an axis-central through opening delimited by a tubular element extending parallel to the flow direction. Multiple separate flow segments are formed along the tubular element and are evenly distributed in the circumferential direction. The flow segments in the circumferential direction are each separated from one another in terms of flow by flow guide elements extending radially outward from the tubular element.

An air moving device has a housing with a primary flow path and a secondary flow path that extends from a secondary inlet of the housing and empties into an inner outlet adjacent the primary flow path. An impeller assembly rotates a blade to cause air to enter the housing and flow along the primary flow path. The flow of air through the primary flow path creates a low pressure region at the inner outlet of the secondary flow path, causing air to flow through the secondary flow path and mix with the air in the primary flow path. The mixture of air flows through a downstream portion of the primary flow path having an expanded width compared to an upstream portion of the primary flow path and exits the housing. Stator vanes may extend longitudinally within the housing to cause columnar air flow. The device may be used for destratification of thermal gradients of air within an enclosure, such as a home or warehouse.

A blower including a body having a length, L, as measured between front and rear ends of the blower in a direction of airflow through the blower; and a fan including a plurality of blades configured to generate airflow through the blower, wherein the blades are spaced apart from the rear end of the blower by at least 0.4 L. In an embodiment, the fan is rotatably biased by a motor spaced apart from the rear end of the blower by at least 0.5 L. In another embodiment, at least 75% of the fan is disposed within an airflow outlet tube of the blower. In yet another embodiment, the blower further comprises a handle, and wherein the fan is disposed downstream of the handle, and wherein the fan is spaced apart from the handle by at least 0.08 L, as measured in the direction of airflow.