A ventilation assembly includes a main housing comprising a first housing wall and a second housing wall, a fan assembly disposed within the main housing, the fan assembly including a fan, and an acoustic device disposed between said first and second housing walls, the acoustic device having a first distal portion, a second distal portion and an intermediate portion extending between the first distal portion and the second distal portion, the first distal portion being relatively wider than the intermediate portion.

A ventilation assembly having a main housing that can be pre-installed in a wall or ceiling aperture. A fan assembly can be inserted through the aperture and releasably mounted within the main housing. The fan assembly can be removed from the main housing and replaced without removing the main housing from the wall or ceiling. An accessory component can be releasably mounted to the fan assembly either through the aperture when the fan assembly is mounted or prior to installation of the fan assembly.

Fans having fan blade mounting structures are disclosed herein. A fan configured in accordance with one embodiment of the present technology includes a fan having a central hub coupled to a plurality of fan blades by a plurality of blade mounting structures. Each blade mounting structure can include first and lower support members that each extend toward an inboard end portion of an individual fan blade. Each of the upper and lower support members can include a first end portion coupled to the inboard end portion of the fan blade. Each of the upper and lower support members can also include a second end portion coupled to opposite sides of the central hub.

A gas turbine engine fan section includes a fan hub configured to rotate about an axis. A nose cone includes a spinner operatively mounted to the fan hub. The spinner supports a first fastening element and the nose cone includes an annular cover arranged over the fastening element. The spinner and annular cover provide an aerodynamic exterior surface of the nose cone without exposed fasteners. A second fastening element cooperates with the first fastening element to secure the spinner relative to the fan hub. The first and second fastening elements are oriented transversely to the axis.

A blower assembly includes a housing including an outlet and a cutoff point positioned proximate the outlet. The blower assembly also includes an impeller including a plurality of blades that each includes a tip portion including a radially outer edge and a transition point that divides the radially outer edge into a first portion and a second portion. The impeller is positioned within the housing such that a first radial gap is defined between the cutoff point and the first portion and a second radial gap is defined between the cutoff point and the second portion. The first radial gap includes a constant width that is shorter than a width of the second radial gap.

Disclosed aspects relate to cooling electronics. A set of recirculation flaps is coupled with a cooling fan. At least one recirculation flap has a ferrous material. In various embodiments, the set of recirculation flaps is arranged in an open position in response to air pressure from the cooling fan, and is arranged in a closed position in response to substantially no air pressure from the cooling fan. A controller is coupled with the cooling fan. The controller indicates a set of indicated positions for the set of recirculation flaps based on a tachometer value. An electromagnet is connected with the controller to position the set of recirculation flaps in the set of indicated positions using the ferrous material. In various embodiments, the electromagnet engages the ferrous material to arrange the set of recirculation flaps in an open position.

Disclosed aspects relate to cooling electronics. A set of recirculation flaps is coupled with a cooling fan. At least one recirculation flap has a ferrous material. In various embodiments, the set of recirculation flaps is arranged in an open position in response to air pressure from the cooling fan, and is arranged in a closed position in response to substantially no air pressure from the cooling fan. A controller is coupled with the cooling fan. The controller indicates a set of indicated positions for the set of recirculation flaps based on a tachometer value. An electromagnet is connected with the controller to position the set of recirculation flaps in the set of indicated positions using the ferrous material. In various embodiments, the electromagnet engages the ferrous material to arrange the set of recirculation flaps in an open position.

A system for manufacturing a hollow multi-blade rotor includes a manifold having upper and lower manifold sections. The upper manifold section includes sealing ports that include sealing rings. The lower manifold section includes sealing port apertures that are configured to accept the sealing ports of the upper manifold section. The system further includes multiple pressure pads that are configured to collectively form a center hub area of the hollow multi-blade rotor within a mold during manufacturing of the hollow multi-blade rotor. Each pressure pad includes a hollow inner chamber and a hollow bladder extension. Each bladder extension guides an unsealed end of an inflatable bladder up through a sealing port aperture, thereby enabling the unsealed end of the inflatable bladder to be sealed between the sealing port aperture and the sealing ring of a sealing port when the upper manifold section is coupled to the lower manifold section.

A ceiling fan blade includes a foamed layer, two paper layers, and two cover layers. The foamed layer is formed by foaming a polystyrene material. The paper layers are positioned on two opposite faces of the foamed layer respectively The cover layers are positioned on the paper layers respectively so that each paper layer is sandwiched between the foamed layer and one of the cover layers. Thereby, the ceiling fan blade of the present invention is light-weight, low-cost, and easy to manufacture. In addition, energy to rotate the ceiling fan is reduced.