A ventilation and noise reduction system for centralized cooling towers includes a wind outlet sound-reduction structure, a wind inlet sound-reduction channel, a rainwater collection system, and an arrestor device; wherein the integrated sound-absorbing and sound-insulation shed includes a loading-bearing installation structure for a lifting ring, a concrete foundation, a bearing support structure, a ceiling installation structure, a sound-insulation structure and a lighting and sound-insulation structure.

The driving device for providing assisted ventilation comprises an air inlet (15), an impeller (7) provided with blades (8) rotatably driven by a motor (6), and an air outlet (5), the rotation of said impeller (7) being caused by the air circulation through a duct (4) from the air inlet (15) to the air outlet (5), wherein said blades (8) of the impeller (7) are flexible, vibrating at least one of its ends by the thrust caused by said circulating air.

It reduces noise to improve user comfort.

A medical, in particular dental-medical, fan for extracting or compressing a gaseous working fluid, in particular air, comprises a compressor unit with an outer housing, which comprises an inlet opening for the working fluid and an outlet opening for the working fluid, which are fluidically connected to one another, and which defines a compressor sector and a drive sector.

A scroll for a blower assembly includes a motor-mount plate, and a housing configured to be coupled to the motor-mount plate to define an interior blower cavity. The housing comprises inner and outer walls defining a cavity configured to dampen noise and vibrations produced by the blower assembly during operation.

A blower unit can include an outer housing, an inlet subassembly, a fan subassembly, an outlet subassembly, and a grommet. The outer housing can have an aperture extend along a first axis between first and second ends. The inlet subassembly can be received in the first end of the aperture. The fan subassembly can be received in the aperture adjacent to the inlet subassembly and include at least one wire. The outlet subassembly can be received in the second end. The grommet can be positioned between at least part of the second end and the outlet subassembly. The at least one wire can extend through the grommet. The grommet can seal against the at least one wire. The grommet can seal between the outer housing and the outlet subassembly.

According to various embodiments, a mesh assembly may be provided. The mesh assembly may include: a first mesh including a plurality of first holes arranged according to a pattern; a second mesh including a plurality of second holes arranged according to the pattern; wherein the second mesh is provided on top of the first mesh; and wherein at least one hole of the plurality of first holes is at least partially obstructed by the second mesh.

A fan section for a gas turbine engine according to an example of the present disclosure includes, among other things, a fan rotor having fan blades, and a plurality of fan exit guide vanes positioned downstream of the fan rotor. The fan rotor is configured to be driven through a gear reduction. A ratio of a number of fan exit guide vanes to a number of fan blades is defined. The fan exit guide vanes are provided with optimized sweep and optimized lean.

A disclosed fan system includes a housing having side walls, an inflow side, and an outflow side; a fan secured in the housing by a mounting; and a backflow blocker mounted to the side walls within the housing on the outflow side of the housing partially blocking a cross-sectional area of the outflow side. The backflow blocker is positioned approximately centrally in a flow path of the housing and is configured to block part of an airflow cross section such that, between side walls of the housing and side walls of the backflow blocker, an annular duct is formed as an air passage. Further, the backflow blocker has a thickness that is greater than 5% of a width of the housing, and is less than 20% of an axial design height of the fan system.

A sound attenuation device for reducing noise generated by a leaf blower includes a shell, which is insulated and defines an interior space. A first cutout that is positioned in a front of the shell and a second cutout that extends from the front into a first side of the shell are shaped substantially complementarily to an engine compartment of a leaf blower and to a cross-sectional profile of a pipe of the leaf blower, respectively. The first cutout is configured to insert the engine compartment into the interior space so that the pipe extends from the shell through the second cutout. A coupler that is coupled to the shell proximate to the front is configured to couple the shell to the leaf blower so that the shell substantially encapsulates the engine compartment. The shell is configured to attenuate sound that is generated by an engine of the leaf blower.

A blower may include an operation rod extending in a front-rear direction, a rear housing disposed on a rear portion of the operation rod and housing a prime mover, and an attachment detachably attached to a front portion of the operation rod. The attachment may include an air passage pipe housing a fan driven by the prime mover; an intake pipe disposed on a rear portion of the air passage pipe, and a nozzle disposed on a front portion of the air passage pipe. A sound absorbing material may be disposed on an inner surface of the intake pipe.