Nonlinear piecewise restoring force in hydrokinetic power conversion using flow induced motions of single cylinder

OCEAN ENGINEERING

卷:128

Article

Ma, Chunhui¹  Sun, Hai^3,2,4  Nowakowski, Gary⁵  Mauer, Erik⁶  Bernitsas, Michael M.^3,7,8 

[1] Jiangsu Maritime Inst, Nanjing, Jiangsu, Peoples R China

[2] Univ Michigan, Ann Arbor, MI 48109 USA

[3] Univ Michigan, Dept Naval Architecture & Marine Engn, Marine Renewable Energy Lab, 2600 Draper Rd, Ann Arbor, MI 48109 USA

[4] Harbin Engn Univ, Harbin, Peoples R China

[5] US DOE, Wind & Water Power Technol Off, Golden, CO USA

[6] US DOE, Allegheny Sci & Technol, Bridgeport, CT USA

[7] Univ Michigan, Dept Mech Engn, Ann Arbor, MI 48109 USA

[8] Vortex Hydro Energy, Ann Arbor, MI USA

关键词: Hydrokinetic energy;    Nonlinear restoring force;    Flow-induced motions;    Vortex-induced vibrations;    Galloping;    Distributed surface roughness;   

DOI  :  10.1016/j.oceaneng.2016.10.020

来源: Elsevier

【 摘 要 】

Flow Induced Motions (FIMs) of a single, rigid, circular cylinder with piecewise continuous restoring force are investigated for Reynolds number 24,000 <= Re <= 120,000 with damping, and different piecewise functions as parameters. Selective roughness is applied to enhance FIM and increase the hydrokinetic energy captured by the VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) Converter at higher Reynolds numbers. The second generation of virtual spring-damping system Vck, developed in the Marine Renewable Energy Laboratory (MRELab), enables embedded computer-controlled change of viscous-damping and spring-stiffness for fast and precise oscillator modeling. Experimental results for amplitude response, frequency response, energy harvesting, and efficiency are presented and discussed. All experiments were conducted in the Low Turbulence Free Surface Water (LTFSW) Channel of the MRELab of the University of Michigan. The main conclusions are: (1) The nonlinear piecewise spring Converter can harness energy from flows as slow as 0.275 m/s with no upper limit. (2) In galloping, the nonlinear spring Converter has up to 76% better performance than its linear spring counterpart. (3) The FIM response is predominantly periodic for all nonlinear spring functions used. (4) Optimal power harnessing is achieved by changing the nonlinear piecewise spring function and the linear viscous damping. (5) VIVACE exhibits local maxima in power conversion at the end of the upper branch in VIV and the highest velocity reached in galloping. (6) The efficiency optima though are at the beginning of the VIV initial branch and at the beginning of galloping.

【 授权许可】

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