An airflow sensor array based on polyvinylidene fluoride cantilevers for synchronously measuring airflow direction and velocity

Abstract

To solve the problem of the low response voltage of piezoelectric cantilever under the airflow acting, this paper introduces an airflow sensing structure to amplify the vibration amplitude of the cantilever, and the airflow sensor array synchronously apperceives the airflow direction and velocity. Such the sensor array is designed based on a multi-cantilever structure with a groove array frame. We present a fluid-solid-electric coupling model based on the finite element method (FEM), revealing the amplitude magnification of polyvinylidene fluoride (PVDF) cantilever under the action of the airflow. According to the experimental distributions of the response voltages at different flow velocities and angles, we can use the least square method to derive the mathematical relationship among the response voltage, the flow angle and velocity of each PVDF cantilever. Simulation results demonstrate that the amplitude amplification through the grooves frame is about 20 times greater than a traditional exposed cantilever structure. Moreover, the maximum and minimum calculated values of the airflow angle error (Δθexp) are 1.04° and 0.34°, respectively, whereas the maximum and minimum experimental values of the airflow velocity error (Δvexp) are 2.27% and 1.20%, respectively, under twenty random positions at 8.0 m/s within 1 s sampling time. In addition, under the condition of changing flow velocity in real-time, the errors associated with Δθexp and Δvexp respectively range from 0.02° to 1.10° and from 0.2% to 5.5%. Therefore, the airflow sensor array can be beneficial for effectively measuring the airflow direction and velocity.