Hydrokinetic Power Conversion Using Vortex-Induced Oscillation with Cubic Restoring Force

Energies

Sun Hai¹  Mengyu Li¹  Christopher Bernitsas²  Guo Jing³ 

[1] College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China;Marine Renewable Energy Laboratory, Department of Naval Architecture & Marine Engineering, University of Michigan, 2600 Draper Road, Ann Arbor, MI 48109-2145, USA;Mathematical Sciences Department, Worcester Polytechnic Institute, Worcester, MA 01609, USA;

关键词: hydrokinetic energy;    alternating lift technologies;    cubic spring-stiffness;    vortex-induced vibrations;   

DOI  :  10.3390/en13123283

来源: DOAJ

【 摘 要 】

A cubic-spring restoring function with high-deformation stiffening is introduced to passively improve the harnessed marine hydrokinetic power by using flow-induced oscillations/vibrations (FIO/V) of a cylinder. In these FIO/V experiments, a smooth, rigid, single-cylinder on elastic end-supports is tested at Reynolds numbers ranging from 24,000 < Re < 120,000. The parameters of the tested current energy converter (CEC) are cubic stiffness and linear damping. Using the second generation of digital virtual spring-damping (Vck) controller developed by the Marine Renewable Energy Laboratory (MRELab), the cubic modeling of the oscillator stiffness is tested. Experimental results show the influence of the parameter variation on the amplitude, frequency, energy conversion, energy efficiency, and power of the converter. All experiments are conducted in the low turbulence-free surface water (LTFSW) channel of the MRELab of the University of Michigan. The main conclusions are: (1) The nonlinearity in the cubic oscillator is an effective way to extend the vortex-induced vibration (VIV) upper branch, which results in higher harnessing power and efficiency compared to the linear stiffness cylinder converter. (2) Compared to the linear converter, the overall power increase is substantial. The nonlinear power optimum, occurring at the end of the VIV upper branch, is 63% higher than its linear counterpart. (3) The cubic stiffness converter with low harnessing damping achieves consistently good performance in all the VIV regions because of the hardening restoring force, especially at higher flow velocity.

【 授权许可】

Unknown