A fan, and a silencer that silences a sound generated by the fan are provided, in which the silencer has a resonance characteristic, the silencer is disposed at a position connected to a sound field space of the sound generated by the fan, and a sum of an absorbance and a reflectivity of the silencer at a resonance frequency is 10% to 43% and a standardized half-width of the silencer is more than 0.05 and 0.25 or less.

An axial fan that includes a casing having an inner space that penetrates in one direction, and a rotor blade disposed in the inner space of the casing, and a silencer that is disposed at a position connected to the inner space of the axial fan are provided, in which the axial fan has a sound pressure distribution having a position at which a sound pressure is high and a position at which the sound pressure is low in a circumferential direction in the inner space during driving, and the silencer is disposed at the position of the axial fan in the circumferential direction at which the sound pressure is high and is not disposed at the position at which the sound pressure is low.

A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

A compressor includes a rotation shaft which rotates around an axis, an impeller which press-feeds a fluid from one side in an axial direction toward an outward side in a radial direction by rotating together with the rotation shaft, a casing which surrounds the rotation shaft and the impeller and in which an exit flow channel for introducing a fluid press-fed from the impeller is formed, and an acoustic liner which is provided so as to face the inside of the exit flow channel in the casing. The acoustic liner has a plurality of open hole portions which are arranged with intervals therebetween, and acoustic spaces which communicate with the open hole portions and are independently provided for the respective open hole portions.

An air-sending device includes a housing including an inlet air passage communicating with an air inlet and an outlet air passage communicating with an air outlet, a first partition plate partitioning an interior of the housing into the inlet air passage and the outlet air passage, a bell mouth disposed around an opening defined in the first partition plate, and an impeller disposed over the first partition plate across the bell mouth and having a rotation axis that extends in a direction that intersects the first partition plate. The impeller suctions air into the inlet air passage from the air inlet, and blows out air from the air outlet through the outlet air passage. The inlet air passage guides air from the air inlet to the opening along the first partition plate, and has an air-passage wall.

A ventilated seat system for a vehicle includes a seating assembly including a seatback operably coupled to a seat base. A blower is coupled to the seating assembly. The blower generates a sound transmission when activated. The blower includes a housing defining an inlet and an outlet. A first metamaterial silencer is coupled to an interior surface of the housing proximate to the inlet, and a second metamaterial silencer is coupled to the interior surface of the housing proximate to the outlet. Each of the first metamaterial silencer and the second metamaterial silencer reduces the sound transmission generated by the blower.

A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of the fan rotor relative to a speed of the fan drive turbine. A fan case surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection is between the fan case and the core engine includes three triangular-frame connecting members rigidly connected to the fan case at a fan case connection point, and to the core engine at a core engine connection point. The triangular-frame connecting members each are defined by two rigid legs which extend between the fan case and to the core engine, along directions each have a component extending radially inwardly and a component in opposed circumferential directions to each other. A plurality of non-structural fan exit guide vanes and the non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise. The non-structural fan exit guide vanes are rigidly mounted to at least one of the fan case and the core engine.

A compressor includes: a rotation shaft which is allowed to rotate around an axis; an impeller which is configured to pressure-feed a fluid from one side in an axial direction toward an outside in a radial direction by rotating together with the rotation shaft; a casing surrounding the rotation shaft and the impeller and in which an exit flow path guiding the fluid pressure-fed from the impeller is formed; and an acoustic liner which is installed to face an inside of the exit flow path in the casing. The acoustic liner includes: an acoustic space which is formed inside the acoustic liner; an introduction hole communicating the acoustic space with the exit flow path; and a vortex suppressor which is placed in a connection area between the introduction hole and the acoustic space and is configured to suppress vortexes which occur in the connection area.

An airflow guiding device for the sound- and pressure-optimized supply of an airflow to an inlet nozzle of a fan, in particular a radial fan, wherein the inlet nozzle has a nozzle input opening with an incident flow angle, the airflow guiding device having: a frame device which extends along a longitudinal axis in an axial direction with a height between an inlet opening, through which the airflow flows into the frame device in an operating state, and an outlet opening, through which the airflow flows out of the frame device in the operating state, wherein the inlet opening has an inlet cross section with a minimum inlet cross-sectional width, and the outlet opening has an outlet cross section with a minimum outlet cross-sectional width which corresponds to the minimum inlet cross-sectional width or which is smaller than the minimum inlet cross-sectional width, and the frame device comprises a flow duct which connects the inlet opening and the outlet opening in terms of flow, wherein the outlet opening is configured to be connected in terms of flow to the inlet nozzle of the fan in the operating state, characterized in that the height of the frame device according to the following formula h≥(D−d)/(2.Math.tan(β)) corresponds to a ratio of a difference of the minimum inlet cross-sectional width and a diameter of the inlet nozzle and double the value of the tangent of the incident flow angle or is greater than the ratio, and a grid element, which is arranged on the inlet opening.

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.