An apparatus is disclosed. The apparatus has a first housing having a first cavity, a second housing disposed in the first housing and including a second cavity and at least one aperture, a first fan assembly configured to generate a first airflow through the first housing, and a second fan assembly configured to generate a second airflow from the second cavity to the first cavity via the at least one aperture.

A fan noise suppression circuit may be coupled between a power source and a power input to at least one fan. The fan noise suppression circuit may include an adjustable current source coupled to the power source. The adjustable current source may provide a voltage output and a current output based on a power output of the power source. The fan noise suppression circuit may include a feedback controller coupled to an output of the adjustable current source. The feedback controller may be configured to compare the voltage output to a reference voltage and provide an error value to the adjustable current source, wherein the adjustable current source may adjust the current output based on the error value.

A fluid-flow machine includes at least one rotor having a rotary element with a plurality of rotor blades arranged on the rotary element, and a circumferential casing having a central axis and surrounding the rotor. The circumferential casing or a part connected thereto has an annular space surface on the inside, which delimits a flow duct of the fluid-flow machine radially outwards. The annular space surface has a structuring at least in one area adjoining a rotor on the circumferential side. At least one structuring of the annular space surface has, relative to the central axis of the circumferential casing, a circumferentially asymmetrical design.

The invention relates to a device for controlling the swirl of a fluid (2) flowing in a pipeline (1). The invention was based on the object of creating a device with which the adaptation of the swirl (2B) of a fluid (2) flowing in a pipeline (1), even in the case of constantly changing initial swirl (2B), to the desired flow conditions in the pipeline (1) is possible. Said object is achieved in that a swirl measuring device (4) and a swirl control device (6) are provided at predetermined positions of the pipeline (1), and the device has an evaluation and encoder unit (5), wherein, in the presence of differences between the measured actual swirl (2B) and the desired swirl, a corrective value can be determined by means of the evaluation and encoder unit (5), and the swirl control device (6) corresponds with the evaluation and encoder unit (5) and, by means of the swirl control device (6), the present swirl (2B) can be adapted to the predetermined desired swirl in accordance with the determined corrective value.

An electric powered work machine according to one aspect of the present disclosure includes a first and a second digital filters, a control sound source, an error sensor, and a characteristics adjustor. The first digital filter includes a series of taps and generates a control signal. The control sound source produces an artificial noise in accordance with the control signal. The error sensor converts a synthesized sound of the artificial noise and a target noise at a canceling location to an error signal. The second digital filter includes N taps and generates a filtered reference signal. The characteristics adjustor uses the error signal and the filtered reference signal to adjust a coefficient of each tap of M taps in the series of taps. Each of M and N is a positive integer satisfying M<N.

Disclosed is a cross-flow fan including a fan rotor and a housing. The cross-flow fan has a blow-out path defined by first and second extension wall portions and two sidewalls. The first extension wall portion continuously extends from a tongue portion of the housing to the blow-out port. The second extension wall portion faces the first extension wall portion. The two sidewalls are respectively provided at axial ends of the fan rotor. The two sidewalls are formed such that the blow-out path has a narrowed portion whose cross-sectional area decreases as its cross-sectional shape changes from a rectangular shape to a trapezoidal shape from an upstream side toward a downstream side thereof, the trapezoidal shape having a portion near the second extension wall portion smaller in width than a portion near the first extension wall portion.

A fan frame is provided and includes a body and a first cover plate. The body includes a main surface and a first side which is substantially perpendicular to the main surface. A first channel and a second channel, which are adjacent to each other, are formed in the body, and a first space is formed among the main surface, the first side, a sidewall of the first channel, and a sidewall of the second channel. The cover plate is disposed on the body, and covers the first space, wherein a first hole is formed in the first cover plate, and the first space communicates with the external environment via the first hole.

A section for a gas turbine engine according to an example of the present disclosure includes, among other things, a rotor including a row of blades extending in a radial direction outwardly from a hub. The row of blades deliver flow to a bypass flow path, an intermediate flow path, and a core flow path. A first case surrounds the row of blades to establish the bypass flow path. A first flow splitter divides flow between the bypass flow path and a second duct. A row of guide vanes extends in the radial direction across the bypass flow path. A second flow splitter radially inboard of the first flow splitter divides flow from the second duct between the intermediate flow path and the core flow path. A bypass port interconnects the intermediate and bypass flow paths. A method of operation for a gas turbine engine is also disclosed.

A blowing system includes: a first blowing unit including a first body that houses a first fan and includes a first air outlet for blowing-out wind from the first fan; a second blowing unit including a second body that houses a second fan, includes a second air outlet for blowing-out wind from the second fan, and has a shape that is in two-fold symmetry with the first body; and a first connection that rotatably-connects an edge on a back face-side of a first side face of the first body and an edge on a back face-side of a second side face of the second body so that an angle formed by the first and second bodies is variable. The first and second blowing units come into contact at three or more points, and the directions of respective rotation axes of the first and second fans cross at a predetermined angle.

The invention relates to a housing (1) for a fluid machine, in particular for a radial fan (2), comprising at least one housing part (3), wherein the housing pail (3) has at least one inlet opening (7), wherein the housing part (3) can at least partially delimit a fluid chamber (8) for receiving at least one fan wheel (9), and wherein the inlet opening (7), at least in part, has a coned inlet surface (11) To produce a housing (1) for a fluid machine, in particular a housing (1) for a radial fan, preferably for use in a car seat and offering reduced noise emission together with good performance, the curved inlet surface (11) has at least in part the furan of a logarithmic spiral in cross-section, aridly at least one guide element (21) extends from the inlet surface (11) towards a central axis of the inlet opening (7), and/or on the inside (17) of the housing part (3) there is provided a circumferential recess (25) which at least partially circumferentially