Experimental Aeroelastic Investigation using Piezoelectric Transducers in Wind Tunnel Testing

Piezoelectric materials have been increasingly applied to a wide range of engineering and scientific applications in the past three decades. One application of interest involves wind tunnel testing to quantify and evaluate the aeroelastic behavior of aircraft wings. In this paper, the focus is on the suitability of piezoelectric sensors, namely PVDF (Polyinylidene Fluoride), to quantify the aeroelastic response of wing models by acquiring modal parameters, i.e. the natural frequencies and damping factors of the vibration modes. Concurrently, a complementary goal is to use PZT (Lead Zirconate Titanate) materials as actuators to better excite the vibration modes that are not adequately energized by the aerodynamic flow. During the setup phase of the experimental apparatus, several studies were performed to help define the test parameters. The aeroelastic tests were conducted in a wind tunnel using a single PZT as actuator and a single PVDF as sensor. The modal parameters obtained using a single PVDF sensor response were then compared with those estimated using laser doppler vibrometry. These parameters were then used to estimate the pre-flutter speed, using both sensing techniques, for three case studies with different mass ballast configurations. A very good agreement was observed between the two sensing techniques, when comparing the results in terms of the frequencies and damping factors of the mode shapes leading to flutter. The results show the suitability of using a single PVDF sensor to estimate the modal parameters, in very turbulent and noisy conditions that are characteristic in wind tunnel testing. PZT is found to reduce the exogenous noise caused by the aerodynamic flow when considering a high number of averages.