A method of forming a sound attenuator around a compressor of an air conditioning system includes covering the compressor with a flexible protective cover and depositing a plurality of materials proximate an outer surface of the flexible protective cover such that at least some of the plurality of materials can chemically react to create a self-forming foam that abuts at least some of the flexible protective cover to thereby create the sound-attenuating structure around the compressor.

A sound damper and associated system are disclosed for damping sound. In embodiments, the sound damper is utilized within an automotive HVAC system. A passage wall defines an air passageway that transmits air. The sound damper includes a micro perforated panel (MPP) located within an opening formed into a passage wall. A back wall is spaced from the MPP, and a cavity is provided between the back wall and the MPP that is outside the air passageway. In embodiments, the MPP can be covered by a non-perforated film that is acoustically transparent and air impermeable.

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 insulation arrangement for an air-conditioning system may include a gas-tight housing and a sound insulation element. The housing may include an air inlet and an air outlet. The sound insulation element may be composed of an insulation material and may be fixed in the housing. The sound insulation element may have an inlet side disposed about the air inlet and an outlet side disposed about the air outlet such that the sound insulation element defines an air conduit in the housing.

Systems and devices of the various embodiments may provide a low-drag, variable-depth acoustic liner having shared inlet volumes. Various embodiments may include a low-drag, variable-depth acoustic liner providing aircraft noise reduction. Acoustic liners according to the various embodiments may be used in engine nacelles and/or on external surfaces of an aircraft to reduce acoustic radiation. Acoustic liners according to various embodiments may provide increased broadband acoustic performance with less drag than conventional liners. Various embodiments may provide an acoustic liner with a reduced open area of the facesheet, and therefore reduced drag of the liner, when compared with conventional acoustic liners.

A ventilation assembly and methods of forming the same includes a ventilation grille having reducing acoustic bodies configured to attenuate sound of the ventilation assembly. Arrangement of the acoustic bodies can form phononic crystal to attenuate sound and can be tuned to desired sound bands to reduce sounds.

Architectures and techniques are presented that can facilitate improved design and function of certain heating, ventilation, and air conditioning (HVAC) devices. Architectures directed to an improved evase device can be designed with rounded corners that can facilitate, e.g., mitigation of reverse flow that traditionally grows back from corners of a transition from an axial fan to a rectangular duct. Architectures directed to an improved intake device can be designed to limit intake from certain flow directions and to smoothly change flow direction, which can facilitate, e.g., reduction in noise. Architectures directed to an improved fan intake device can be designed to reduce noise without significantly reducing total pressure. Architectures directed to an improved air handler device can be designed to concurrently heat and cool air and to reduce dimensions (e.g., size, weight) that can reduce costs and mitigate shipping and installation difficulties.

A duct includes a rigid air-permeable tube of composite material. The duct also includes a layer of insulation coupled to an exterior surface of the rigid air-permeable tube. The duct further includes a non-rigid insulation layer in contact with the layer of insulation. The non-rigid insulation layer forms an air-impermeable duct wall.

A noise barrier is adapted for use in an apparatus which produces noise during operation and which includes at least one blower for generating an airflow along a path through the apparatus. The noise barrier has one or more through holes and is configured to be placed in the path of the airflow for attenuating sound which propagates along the path in the airflow. The noise barrier is made of at least one sound attenuating polymeric foam, in particular a polyurethane foam. In order to achieve better sound attenuating properties the polymeric foam of the noise barrier has an airflow resistivity, measured in accordance with ISO 9053-1:2018, Part 1, which is higher than 50 000 Ns/m.sup.4. Moreover, the dynamic Young's modulus of the polymeric foam is preferably smaller than 250 kPa.

Supply Air device (1) for controlling supply air flow to a building space, comprising a chamber (2) having a supply air inlet (3) and an air outlet (4). A first tube (10) in the chamber is connected at an open first end (11) to the supply air inlet, wherein the first tube has a side wall (13) which is permeable to air. A throttle member (30) is slidably connected to the first tube to change a degree of exposure of the side wall to control air flow through said side wall to the outlet. The exposable side wall comprises a layer of porous material (14) through which air is discharged.