Effects of flow velocity and length-to-depth ratio on low-speed rectangular cavity flow oscillations for clean energy harvesting

Singh, Abhishek, Thangamani, Varun, Kok, Foo Ngai and Vanderwel, Christina (2023) Effects of flow velocity and length-to-depth ratio on low-speed rectangular cavity flow oscillations for clean energy harvesting. Gaber, Hossam (ed.) In Proceedings of the 5th International Conference on Clean Energy and Electrical Systems. CEES 2023. vol. 1058, Springer Singapore. pp. 387-401 . (doi:10.1007/978-981-99-3888-9_28).

Abstract

Low-speed cavity flow oscillations have been found to be a potential source for harvesting energy from flow-induced vibrations. An investigation was conducted using wind tunnel experiments to analyze the effect of flow velocity and cavity length-to-depth ratio on low-speed cavity flow oscillations. This study aims to find the most suitable cavity and flow velocity configuration to harvest clean oscillatory energy from the flow. Cavities with five length-to-depth (L/D) ratios of 1, 2, 3, 4 and 6 have been considered with flow velocities at 10, 15, 20, 25 and 30 m/s. The cavity tone amplitudes showed a general increase in amplitude with an increase in velocity up to 25 m/s and slightly dropped at 30 m/s, except for the cavity with L/D = 2. The Total Spreaded Acoustic Power (TSAP) was found to increase with an increase in velocity. The results showed that cavities with L/D = 1 and 6 do not exhibit cavity tones, and the noise in the frequency spectra was found to be broadband. Cavities with L/D = 2, 3 and 4 showed high-amplitude flow oscillations with frequencies that matched Rossiter’s semi-empirical model. Cavity with L/D = 3 showed flow oscillations with the highest amplitude, although the frequency peak of the cavity with L/D = 2 had a better Quality (Q) factor. Overall, the cavity with L/D = 3, at a flow velocity of 25 m/s, was found to be the best choice for energy harvesting.

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Contributors

Author: Christina Vanderwel

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