Influence of spacing ratio on energy harvesting from water current by cylinder arrays
Luo Zhumei1, Zhang Lixiang2
1.Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China; 2.Faculty of Civil Engineering and Architecture, Kunming University of Science and Technology, Kunming, Yunnan 650051, China
The vortex-induced vibration of five cylinders rigidly linked at both ends with staggered arrangement was simulated under a uniform current. A two-way coupling numerical method was adopted to deal with fluid-structure interaction when the cylinder arrays were subject to a current respectively with 0.5 m/s, 0.6 m/s and 0.7 m/s velocities. Further, different streamwise and transverse spacing ratios were applied in simulations to identify their influence on energy harvesting and power density from the current at three stream velocities. The results reveal that there is no obvious vortex shedding and the amplitude of response of cylinder system is very small at low space ratios. However, as the space ratios are high enough, there is vortex shedding from each cylinder at the same frequency and the cylinder system obtains high response amplitude. The energy harvesting is enhanced with increasing spacing ratios, however, it becomes statured once the streamwise spacing ratio L/D≥6 and the transverse spa-cing ratio H/D≥4. Furthermore, a maximum power density occurs at L/D=6 and H/D=4 under the three current velocities. Therefore, L/D=6 and H/D=4 should be the reasonable two spacing ratios. This result can be useful for design of cylinder arrays for energy harvesting from water currents.
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