# Design and Development of Bladeless Vibration-Based Piezoelectric Energy-Harvesting Wind Turbine
## 6 Conclusions  
This paper proposed a novel and new VIV design to harvest and convert mechanical energy to electric energy using a vortex-induced vibration technique. The proposed design is a blackeles elastic rod that vibrates when wind interacts with it. Out of the mechanical vibrations and rod oscillations, electric energy can be harvested through piezoelectric sensors attached to the mast at three locations. The design is environmentally friendly, with comparably good reliability. The effect of changing the vortex generator shape on the VIV phenomenon and VIV energy harvesting was investigated numerically and experimentally. Three different inlet wind velocities were investigated for three different vortex generator geometries: a simple cylinder, a modified cylinder, and a real-world-sized complex cylinder vortex generator. CFD simulations were performed to investigate the flow pattern and the generated vortices. Velocity, pressure, and vorticity contours were generated and analyzed. Piezoelectric sensors were utilized to measure generated power. Their optimal locations were also investigated. More importantly, the transient behavior of the lift coefficient over time is given for each case. The results of the numerical study demonstrate that increasing the inlet wind velocity increases the maximum magnitude of the lift coefficient, its frequency, and the time needed to reach the pseudo-steady situation in this problem, which has a transient nature. In addition, adding complexity to the cylinder geometry substantially enhances the maximum lift force applied to the vortex generators and can boost the efficiency of VIV energy harvesting. The trends of the numerical results are found to be in good agreement with those of the experimental tests. The experimental results show that the location of the piezoelectric sensor influences the amount of generated power. Increasing the distance from the vortex generator object does not directly increase the generated power, and this could be because the mast obstructed the wind flow around the vortex generator and the constraint for mast movement. If such designs are refined and enhanced in terms of design geometry and the materials utilized in manufacturing the mast of the VIV design, a good quantity of power can be created. The developed and tested methods yielded good results. Conceptualization, Z.D. and A.Y. ; Data curation, A.Y., H.S. and A.A. ([PERSON]); Formal analysis, A.Y., A.A. ([PERSON]), H.S. and A.A. ([PERSON]); Investigation, A.Y. ; Methodology, A.Y. ; Resources, Z.D., A.Y., M.E. and H.S. ; Software, A.Y. and A.A. ([PERSON]); Supervision, A.Y. ; Validation, A.A. ([PERSON]); Visualization, A.Y., M.E. ; Writing--original draft, A.Y. ; Writing--review & editing, Z.D. and A.Y. All authors have read and agreed to the published version of the manuscript. This research received no external funding. **Institutional Review Board Statement**: Not applicable. **Informed Consent Statement**: Not applicable. **Data Availability Statement**: Not applicable. **Conflicts of Interest**: The authors declare no conflict of interest. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **Velocity** \\ **(m/s)** \\ \end{tabular} & \begin{tabular}{c} **Top (mmV)** \\ \end{tabular} & \begin{tabular}{c} **Middle** \\ **(mmV)** \\ \end{tabular} & \begin{tabular}{c} **Bottom** \\ **(mmV)** \\ \end{tabular} & \
\begin{tabular}{c} **Drag Force** \\ **(N)** \\ \end{tabular} &
\begin{tabular}{c} **Lift Force** \\ **(N)** \\ \end{tabular} \\ \hline
5 & 3.4 & 1.7 & 2.9 & 4.7 & 1.9 \\
6 & 3.5 & 2.5 & 3.5 & 4.6 & 1.9 \\
7 & 3.8 & 2.8 & 4.5 & 4.6 & 2 \\
8 & 3.9 & 2.8 & 4.8 & 4.5 & 2 \\
9 & 4 & 2.9 & 5.2 & 4.4 & 2 \\
10 & 4 & 2.9 & 8 & 4.4 & 2.1 \\
11 & 4.1 & 3.1 & 8 & 4.3 & 2.1 \\
12 & 4.4 & 3.2 & 8.3 & 4.2 & 2.1 \\
13 & 4.8 & 3.3 & 9 & 4.1 & 2.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental results for the complex cylinder case with mast angle of attack at 5 deg. Figure A4: Combined results for case 1 (mast angle at 0 degrees).