Flow velocity measurements using piezoelectric bimorph beam in external fluid flow

This paper presents a new method to determine the external flow velocity using piezoelectric sensors. In this method, the piezoelectric sensor is molded as a composite bimorph beam including an aluminum layer, two piezoelectric layers as sensor layers, and a concentrated mass at the free end. The coupled electromechanical nonlinear differential equations governing the dynamic deformation of the bimorph beam related to the external fluid flow have been extracted from nonlinear theory based on Cosserat assumptions. After numerically solving the coupled nonlinear equations, the effect of various parameters on the voltage generated by the piezoelectric layers and its dependence on the fluid flow velocity is examined. The results indicate that as the fluid velocity increases, the voltage rises nonlinearly. Moreover, applying concentrated mass at the end of the bimorph beam leads the maximum voltage generated to increase by 4.8 times compared to that without concentrated mass. Considering the results, it can be concluded that the sensitivity of the proposed piezoelectric sensor to the fluid flow velocity is significant, and through using it, the fluid flow velocity within different types of channels can be determined effortlessly affordably.