A sound suppression assembly is provided for absorbing acoustic energy from an air circulation device. The assembly includes an air circulation device, such as an axial fan, and a plurality of sparsely-arranged two-sided Helmholtz unit cells disposed in a periodic array. Each unit cell includes a lossy resonator and a lossless resonator. The lossy resonator includes a first chamber portion bounded by at least one first boundary wall defining a first chamber volume, and a first neck forming an opening in the first chamber portion. The lossless resonator includes a second chamber portion bounded by at least one second boundary wall defining a second chamber volume, and a second neck forming an opening in the second chamber portion. The unit cells can be positioned in a circular pattern with the first neck of the lossy resonators directed to a source of acoustic energy from the air circulation device.

A method includes providing a first metal sheet and a second metal sheet, printing patterns of a plurality of obstructers, a plurality of channels, an evaporator channel, a condenser channel, and a connecting channel on the first metal sheet, bonding the first metal sheet and the second metal sheet to each other, separating the first metal sheet and the second metal sheet from each other to form the plurality of channels, the evaporator channel, the condenser channel, and the connecting channel by introducing a fluid between the first metal sheet and the second metal sheet, introducing working fluid in the plurality of channels, and sealing the first metal sheet and the second metal sheet.

A method includes providing a first metal sheet and a second metal sheet, printing patterns of a plurality of obstructers, a plurality of channels, an evaporator channel, a condenser channel, and a connecting channel on the first metal sheet, bonding the first metal sheet and the second metal sheet to each other, separating the first metal sheet and the second metal sheet from each other to form the plurality of channels, the evaporator channel, the condenser channel, and the connecting channel by introducing a fluid between the first metal sheet and the second metal sheet, introducing working fluid in the plurality of channels, and sealing the first metal sheet and the second metal sheet.

The heat exchanger includes an inner casing extending circumferentially around the central axis and securable to the shaft for concurrent rotation therewith, and an outer casing extending circumferentially around the central axis and secured to the inner casing, the outer casing located radially outwardly of the inner casing relative to the central axis. First conduits are secured to the outer casing and to the inner casing for rotation about the central axis, the first conduits located radially between the outer casing and the inner casing, and circumferentially distributed about the central axis. First passages are defined in the first conduits. Second passages are circumferentially interspaced between the first passages and are located radially between the inner casing and the outer casing. The second passages are in heat exchange relationship with the first passages.

The heat exchanger includes an inner casing extending circumferentially around the central axis and securable to the shaft for concurrent rotation therewith, and an outer casing extending circumferentially around the central axis and secured to the inner casing, the outer casing located radially outwardly of the inner casing relative to the central axis. First conduits are secured to the outer casing and to the inner casing for rotation about the central axis, the first conduits located radially between the outer casing and the inner casing, and circumferentially distributed about the central axis. First passages are defined in the first conduits. Second passages are circumferentially interspaced between the first passages and are located radially between the inner casing and the outer casing. The second passages are in heat exchange relationship with the first passages.

An electric motor may include a stator assembly comprising a stator housing, and one or more rotors coupled to the stator by a rotor shaft assembly. The stator housing may include a cooling structure that has a plurality of cooling body portions and a plurality of cooling conduits defined by the plurality of cooling body portions. A method of forming a stator housing for an electric machine may include additively manufacturing a stator housing that includes a cooling structure defining a fluid domain, coupling a working fluid source to the stator housing and introducing a working fluid into the fluid domain defined by the cooling structure, and sealing the cooling structure with the working fluid contained within the fluid domain of the cooling structure. A method of cooling an electric machine may include heating the working fluid in the fluid domain and flowing the working fluid through the fluid domain, and transferring heat from the cooling structure to a cooling fluid flowing along one or more cooling surfaces contacting a surface of the electric machine.

The heat sink with condensing fins and phase change material is formed from a thermally conductive housing, an internal chamber, and a body of liquid phase change material. The thermally conductive housing has a first wall and an opposed second wall and forms an internal chamber. The first wall of the thermally conductive housing is adapted to be in direct contact with one or more heat sources. The body of liquid phase change material is disposed within the internal chamber. The second wall of the thermally conductive housing is adapted to form a plurality of condensing fins. The plurality of condensing fins may contain at least one high thermal conductivity rod. In some embodiments, a high thermal conductivity medium, such as gallium, is disposed within the internal chamber in direct contact with the first wall of the thermally conductive housing.

A heat exchanger for providing thermal energy transfer between a first flow along a first flowpath and a second flow along a second flowpath has at least one plate bank having a plurality of plates, each plate having: a first face and a second face opposite the first face; a leading edge along the second flowpath and a trailing edge along the second flowpath; a proximal edge having at least one inlet port along the first flowpath and at least one outlet port along the first flowpath; and at least one passageway along the first flowpath. An inlet manifold has a first face to which the plurality of plates are mounted along their respective proximal edges. An inlet plenum has at least one inlet port and at least one outlet port. An outlet plenum has at least one outlet port and at least one inlet port. The first flowpath passes from the at least one inlet port of the inlet plenum, through the at least one passageway of each of the plurality of plates, and through the at least one outlet port of the outlet plenum. For each plate, the manifold first face has a respective associated slot capturing a portion of the plate along the proximal edge thereof to prevent extraction of the plate normal to the face.

A heat exchanger includes a body defining a flow channel, and a pin extending across the flow channel, the pin including an at least partially non-cylindrical shape. The pin can be a double helix pin including two spiral branches defining a double helix shape. The two branches can include a uniform winding radius. The two branches include a non-uniform winding radius. The non-uniform winding radius can include a base radius and a midpoint radius, wherein the midpoint radius is smaller than the base radius. The two branches can be joined together by one or more cross-members.

An additively manufactured heat exchanger includes a main body and a plurality of wavy fins. The plurality of wavy fins are disposed in the main body to define flow paths for heat transfer. Each wavy fin has an inner wall forming a channel including radiused corners throughout a length of the wavy fin.