Abstract: A discharge collector and diffuser for a screw compressor, including a housing having an inlet for receiving flow from a compressor and an outlet and defining therebetween a collector portion, a transition portion and a diffuser portion, the collector portion being adapted to receive a plurality of non-parallel streams from a compressor and to guide the streams into a substantially parallel flow direction, the housing further having a splitter plate positioned in the collector portion to separate the non-parallel streams from each other, whereby the streams are maintained separate until they are substantially parallel, thereby reducing flow losses.

Abstract: A discharge collector and diffuser for a screw compressor, including a housing having an inlet for receiving flow from a compressor and an outlet and defining therebetween a collector portion, a transition portion and a diffuser portion, the collector portion being adapted to receive a plurality of non-parallel streams from a compressor and to guide the streams into a substantially parallel flow direction, the housing further having a splitter plate positioned in the collector portion to separate the non-parallel streams from each other, whereby the streams are maintained separate until they are substantially parallel, thereby reducing flow losses.

Abstract: The nozzle of an acoustic jet directs high momentum flux gas particles essentially tangentially into the boundary layer of the flow in a diffuser, an engine air inlet, a jet engine gas flow path or on the suction surface of an airfoil, the gas particles in the chamber of the tangential acoustic jet being replenished with approaching low momentum flux particles drawn from the gas flow in a direction normal to the surface, thereby to provide a net time-averaged flow of increased momentum flux particles to defer the onset of boundary layer separation and/or reduce the thickness of the boundary layer. The acoustic jet is driven by a gas pressure oscillation generator which may be a loudspeaker, a resonant solenoid piston, a cranked piston, or the like.

Abstract: Existing pressure oscillations created by axial or centrifugal fans in a diverging shroud are utilized to power a passive, acoustic jet, the nozzle of which directs high momentum flux gas particles essentially tangentially into the boundary layer of the flow in a diffuser, or a duct, the fluid particles in the resonant chamber of the passive acoustic jet being replenished with low momentum flux particles drawn from the fluid flow in a direction normal to the surface, thereby to provide a net time averaged flow of increased momentum flux particles to defer, even eliminate, the onset of boundary layer separation in the diffuser or duct. The passive acoustic jet is used in the vicinity of fan blade tips to alleviate undesirable flow effects in the tip region, such as leakage.

Abstract: The internal fan arrangement of an AHU is reconfigured by discharging directly from the scroll into a 90.degree. elbow. The bend of the elbow defines a converging section terminating in a throat which leads to a diverging section. Additionally, the ANC structure is located in the elbow with the noise sensing microphones being located at or near the fan outlet.

Abstract: An active noise (or vibration) control system having an actuator 24 which provides an acoustic anti-noise signal in response to an drive signal (U), an error sensor 16 which senses the acoustic anti-noise signal from the actuator, senses disturbance noise (d), and provides an error signal (e) indicative of a combination thereof, and a controller 20, responsive to the error signal (e), which provides the drive signal (U) to the actuator 24, is provided with controller compensation 78 having energy states 112 and having non-linear reset logic 130 which temporarily resets the energy states 112 in the filter 78 to zero when the error signal crosses zero, thereby improving the bandwidth of the active noise control system.

Abstract: An acoustic sensing means such as a microphone or a thin-film sensor is located in a flowing medium. To prevent the sensing of flow generated noise, the sensing means is separated from the flowing medium by at least three stages of shielding. In a preferred embodiment, the sensing means is located within a foam shield which is located in a frame covered by a fabric shield and which is, in turn, located in a second frame covered by a second fabric shield. A spandex fabric is suitable for use in the present invention.