Flowmeter based on a piezoelectric PVDF tube

[Display omitted] •A commercial PVDF tube was spectroscopically characterized.•The presence of the piezoelectric β-phase was confirmed.•The PVDF tube was tested in a hydraulic circuit with varying flow rates.•The voltages generated by the PVDF tube due to flow-induced vibration were measured.•It is possible to use the PVDF tube as a flow-induced vibration flowmeter. The present work aims at demonstrating the applicability of using tubes made of the polymer PVDF as intrinsic flowmeters, considering the peculiar piezoelectric properties of the PVDF-β polymorph and using as flow measurement method the Flow-Induced Vibration (FIV) technique. The work methodology consisted of initially characterizing the material of a commercial PVDF tube spectroscopically, using the Fourier Transform Infrared Spectroscopy (FTIR) technique, to confirm the presence of PVDF-β. Then, the PVDF tube was installed in a hydraulic test circuit and electromechanically tested, to identify the levels of electrical voltages generated by the vibration caused by the passage of water through the tube. To compare the vibration signals, simultaneous measurements were made with commercial accelerometers and with a commercial PVDF film built specifically as a piezoelectric transducer. The results of the FIV tests allowed confirming that the standard deviation of the voltage signal measured by the PVDF tube is related to the flow rate. The uncertainties associated with flow rate measurement by the tube showed a considerable reduction in the higher flow rates. On the other hand, in the lowest flow rate levels, a high instability was observed, possibly due to the process of initial mechanical accommodation of the tube. Despite this, a strong relationship between the signal generated by the PVDF tube and the flow rate that induced this vibration has proven the potential applicability of the PVDF tube as a water flowmeter.