Ultrasonic flow meter with piezoelectric transducer arrays integrated in the walls of a fiber-reinforced composite duct

The integration of piezoelectric transducers into composite components allows for both the measurement and the excitation of plate waves within the component. A common use for plate waves in composite components is structure health monitoring. In the presented work, however, the radiation of ultrasound from the surface of the component due to plate waves in the component is utilized, i.e. fiber-reinforced plastic (FRP) plates with integrated arrays of piezoelectric macro fiber composite (MFC) transducers are used as ultrasound transmitter and receiver. Building on that, the measurement of sound transit times between two facing FRP walls of a duct is used for the determination of the flow velocity of the fluid inside the duct. In that way, a flow meter integrated in the walls of a duct made of composites is built.