Ultrasound Flow Sensor Based on Arrays of Piezoelectric Transducers Integrated in a Composite

The functionalization of fiber-reinforced polymer composites by integration of piezoelectric transducers allows for both the measurement and the excitation of guided waves within the component. A common use for guided waves in composite components is nondestructive examination. In the presented work, however, the radiation of ultrasound waves from the surface of the component due to guided waves in the component is utilized. Glass fiber-reinforced polypropylene (GF/PP) plates with integrated arrays of piezoelectric macro fiber composite (MFC) transducers are used as ultrasound transmitter and receiver. The plates are then set up as facing walls of a rectangular duct and the sound transit times between the plates are measured. From the measured sound transit times, the velocity of gas flow inside the composite duct is determined. In that way, a flow sensor integrated in the walls of a flow channel, e.g. an air duct, made of composites is built. This paper focuses on the manufacturing of such an integrated flow sensor.