Abstract:
Energy harvesting considered to be the ultimate source for long term power supply. Extracting energy from vibration produced in a piezoelectric film gain most attention over a period due to its ability to directly converting mechanical strain energy into electrical energy. In this study, we experimentally investigated energy harvesting from a piezoelectric flag in inverted (whose trailing edge was clamped, and leading-edge was free to move) configuration. Experiment is conducted in open water tunnel under an influence of upstream bluff body to find the impact of energy spectral density of flexible flapping on downstream inverted flag by changing flexural rigidity γ, streamwise gap Gx and Reynolds no. and it’s impact on the peak to peak amplitude and voltage generated by piezoelectric flag in term of root means square Vrms as well. Vortex induce vibration to occur at downstream of a bluff body in a flowing fluid. Reynolds no. played an important role in our case it’s ranges from 103−104 with vortex street fully turbulent and outside of boundary layer flow remains in a laminar region. It has been observed that as the bending rigidity increases flapping frequency and peak to peak amplitude AL⁄ of a flag decreases results in a decrease voltage generation. Flapping frequency has been measured at different flexural rigidity which shows the variation in energy spectral density. It has been observed that the highest energy spectral density of flexible flapping occurs at flexural rigidity of 0.01 N.m2. Image processing technique is used to find out peak to peak amplitude and using Fast Fourier Transform (FFT) to find out a dominant flapping frequency in a MATLAB. Output voltage from a piezoelectric flag is being measured using a DAQ (a module in a LabView for accruing analog output voltage). Particle Image Velocimetry used to find vortex interaction with the inverted flag at downstream of the bluff body and a Strouhal number from particle movement in successive frame.
