Abstract: A system for detecting velocity airflow in a duct includes a plurality of vortex shedders arranged within the duct for inducing the shedding of vortices at a corresponding plurality of selected locations at a frequencies related to the airflow in the duct and a sound-sensing location on each vortex shedder. A plurality of microphones, each microphone being coupled acoustically with each sound-sensing location senses sounds generated by said shedding of vortices in a corresponding passage and provides an information signal indicative of said vortex shedding sounds. A processing unit performs a Fast Fourier Transform on the information signals to determine frequency of maximum amplitude within the information signals.

Abstract: A flow valve with an integral pressure-independent fluid flow controller for controlling the flow of fluid and corresponding methods for controlling fluid flow are provided. The flow valve comprises a valve body, one or more valve blades arranged on the valve body for controlling fluid flow in a duct section, an actuator for modulating the one or more valve blades, a flow sensor or sensors for sensing fluid flow, a tuning calculation module adapted for determining or monitoring a pressure drop across the valve body and for calculating tuning constants based on the pressure drop, and a controller for controlling the actuator based on a difference between a fluid flow setpoint and the sensed fluid flow in accordance with the tuning constants. The pressure drop may be determined from an algorithm based on blade position and sensed fluid flow, or may be directly measured.