Analysis of Wake Region Behind Bluff Body for Piezoelectric Energy Harvester

Mohd Nor Fakhzan Mohd Kazim; Rasidi Rasani; Mohd Zaki Nuawi; Zamri Harun; Yap Khang Hau; Mohd Shukry Abdul Majid

Authors

Mohd Nor Fakhzan Mohd Kazim School of MechatronicEngineering, Universiti Malaysia Perlis(UniMAP), Pauh Putra Campus, 02600 Arau, Perlis, Malaysia
Rasidi Rasani Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti KebangsaanMalaysia (UKM), 43600 UKM Bangi, Selangor, Malaysia
Mohd Zaki Nuawi Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti KebangsaanMalaysia (UKM), 43600 UKM Bangi, Selangor, Malaysia
Zamri Harun Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), 43600 UKM Bangi, Selangor, Malaysia
Yap Khang Hau School of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP),Pauh Putra Campus, 02600 Arau, Perlis, Malaysia
Mohd Shukry Abdul Majid School of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra Campus, 02600 Arau, Perlis, Malaysia

Keywords:

Piezoelectric film, bluff body , wake region, vortex shedding frequency, vorticity, pressure difference

Abstract

Inspired by enhancement of vortex induced vibration energy harvesting as a green and renewable energy source, several geometry shapessuch as cylinder, square, triangle, D shape, and U shape bluff body were studied in terms of vortex shedding frequency, vorticity and pressure difference in order to determine the best bluff body for piezoelectric film. A 2-dimensional computational fluid dynamic (CFD) simulation analysis is carried out with thelength and height of bluff bodyfixed as 0.1m and air flow usedfor simulations are 0.0438m/s, 0.292m/s, and 0.73m/s which corresponds to Reynolds number (Re) of 300, 2000, and 5000. Overall, cylinder, triangle, and D shape bluff body gives a higher vortex shedding frequency and Strouhal Number (St) compare to square and U shape. Triangle bluff body was able to maintain the highest vorticity for all three difference air speeds. It is found that maximum vorticity point will move backwards when higher air velocity is simulated. Nevertheless, triangle bluff body gave the highest-pressure difference reading among all tested shapes. In conclusion, triangle shape bluff body is the most suitable shape for inducing vortex shedding to piezoelectric film and it is suggested the length of the piezoelectric beam is between 0.05m and 0.15m.