Experimental study on energy conversion of flow induced motion for two triangular prisms in staggered arrangement

Abstract

The superiority on energy conversion of triangular prism has been verified by previous studies and the evolution of hard galloping (HG) and soft galloping (SG) with different parameters have also been preliminarily investigated. Based on flow induced motion energy conversion system (FIMECS), the results of oscillation responses and energy conversion for spacing ratio of 0 ≤ S/D ≤ 9, load resistances of 8Ω≤RL ≤ 21Ω and Reynolds number of 46,877 ≤ Re ≤ 108,577 are analyzed and discussed. Additionally, the power density of the FIMECS is calculated based on the test results, to seek the optimal mode of generator arrangement of the FIMECS. The main conclusions can be summarized as follows: (1) For 1 ≤ S/D ≤ 5, the amplitude of staggered upstream triangular prism (S–U-Tri-P) is obviously lower than that of the staggered upstream single prism (S–U-Single-P), but the amplitude of staggered downstream triangular prism (S-D-Tri-P) is higher than that of staggered downstream single prism (S-D-Single-P). For 6 ≤ S/D ≤ 9, vice versa. (2) The phase difference between two staggered prisms with different spacing ratios and different flow velocity are mostly maintained at a stable value. The synergistic oscillation performance of the two staggered triangular prisms is better. (3) In this paper, the optimal active power of two staggered triangular prisms is 26.43 W (S/D = 6), which is significantly 1.7 times that of the single triangular prism (Pharn = 15 W). (4) For spacing ratio of 4 ≤ S/D ≤ 6, which is conducive to ocean current energy utilization and the power density of the FIMECS is in the range of 0.034–0.050 kW/m3 (U = 1.24 m/s).