Abstract: A fluid control device with a reduced sound generation. The device is a nozzle-type valve that has a converging portion, a diverging portion and a throat therebetween. A diverging portion acts as a diffuser and may be conical or may have a slight curvature. In each, the diffusion angle is less than 20° so that turbulence of fluid flowing through the valve is minimized and a boundary layer is maintained between the fluid and an inside surface of the fluid control device. A control system that uses such a fluid control device is also disclosed and such device may be used either in a supply conduit or an exhaust conduit.

Abstract: A resonator as disclosed that has a plurality of resonating chambers having a predetermined size that attenuate sound in a conduit. The resonator may be disposed along the inner periphery of the conduit. Alternatively, it may be disposed on the outside periphery of the conduit so that flow through the conduit may be unrestricted. Additionally, the resonator may include a honeycomb fairing to attenuate sound at higher frequencies. Also disclosed is a system in which a resonator may be located within the conduit of an HVAC system to attenuate the sound.