Hydrokinetic power conversion using Flow Induced Vibrations with nonlinear (adaptive piecewise-linear) springs

Abstract A design, adaptive to the flow velocity, is developed for a hydrokinetic energy converter based on an oscillator undergoing Flow Induced Vibrations (FIVs); primarily Vortex Induced Vibrations (VIV) and galloping. This Alternating-Lift Technology implements a nonlinear spring to passively optimize the oscillator. The FIV of a single, rigid, circular cylinder, with distributed surface roughness, suspended on end-springs with piecewise linear continuous restoring force, are studied for Reynolds number 24,000 ≤ Re ≤ 120,000. Linear viscous damping for energy harnessing and different piecewise linear spring functions are used as parameters. The harnessed power envelope is established based on the results of linear spring stiffness and two nonlinear piecewise stiffness functions. Selective roughness is applied to enhance FIV and increase the hydrokinetic energy captured by the converter at higher Reynolds numbers. The second generation of a virtual spring-damping system (Vck), developed in the Marine Renewable Energy Laboratory (MRELab), enables embedded, real-time, computer-controlled change of viscous damping and spring stiffness for fast implementation of oscillator particulars. Experimental results for amplitude response, frequency response, energy harvesting, and efficiency are presented and discussed. 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) Each nonlinear, piecewise-linear, stiffness function has its own merits in power harnessing; the differences lie in the FIV characteristics of the different regions of the flow. (2) The nonlinear spring converter can harness energy from flows as low as 0.275 m/s with no upper limit. (3) The new adaptive function exhibits higher harnessed power in the upper VIV branch, transition from VIV to galloping, and fully developed galloping regions. (4) The FIV response is predominantly periodic for all nonlinear spring functions used. (5) Optimal power harnessing is achieved by changing the nonlinear piecewise spring function and the linear viscous damping. (6) The optimally harnessed power envelope is established according to the experimental results of the linear and nonlinear stiffness springs; four performance zones are established based on FIV.

[1]  Hai Sun,et al.  Effect of mass-ratio, damping, and stiffness on optimal hydrokinetic energy conversion of a single, rough cylinder in flow induced motions , 2016 .

[2]  Santiago Pindado,et al.  Extracting energy from Vortex-Induced Vibrations: A parametric study , 2012 .

[3]  Michael M. Bernitsas,et al.  Virtual spring-damping system for flow-induced motion experiments , 2015 .

[4]  David T. Walker,et al.  Radar backscatter and surface roughness measurements for stationary breaking waves , 1996, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[5]  Michael M. Bernitsas,et al.  High-damping, high-Reynolds VIV tests for energy harnessing using the VIVACE converter , 2011 .

[6]  Michael M. Bernitsas,et al.  Enhancement of flow-induced motion of rigid circular cylinder on springs by localized surface roughness at 3×104≤Re≤1.2×105 , 2013 .

[7]  Kamaldev Raghavan,et al.  Effect of Bottom Boundary on VIV for Energy Harnessing at 8×103 , 2009 .

[8]  Sang-Gook Kim,et al.  Ultra-wide bandwidth piezoelectric energy harvesting , 2011 .

[9]  Chunhui Ma,et al.  Nonlinear piecewise restoring force in hydrokinetic power conversion using flow induced motions of single cylinder , 2016 .

[10]  Michael M. Bernitsas,et al.  Virtual damper-spring system for VIV experiments and hydrokinetic energy conversion , 2011 .

[11]  Mohammed F. Daqaq,et al.  On intentional introduction of stiffness nonlinearities for energy harvesting under white Gaussian excitations , 2012 .

[12]  M. Bernitsas,et al.  Effect of tip-flow on vortex induced vibration of circular cylinders for Re<1.2*105 , 2016 .

[13]  Eun Soo Kim,et al.  SENSITIVITY TO ZONE COVERING OF THE MAP OF PASSIVE TURBULENCE CONTROL TO FLOW-INDUCED MOTIONS FOR A CIRCULAR CYLINDER AT 30,000, 2017 .

[14]  Peter W. Bearman,et al.  Circular cylinder wakes and vortex-induced vibrations , 2011 .

[15]  Kamaldev Raghavan,et al.  VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow , 2008 .

[16]  Eun Soo Kim,et al.  Hydrokinetic energy conversion by two rough tandem-cylinders in flow induced motions: Effect of spacing and stiffness , 2017 .

[17]  David A W Barton,et al.  Energy harvesting from vibrations with a nonlinear oscillator , 2010 .

[18]  Michael M. Bernitsas,et al.  VIV and galloping of single circular cylinder with surface roughness at 3.0×104≤Re≤1.2×105 , 2011 .

[19]  Turgut Sarpkaya,et al.  A critical review of the intrinsic nature of vortex-induced vibrations , 2004 .

[20]  M. Bernitsas,et al.  Hydrokinetic Energy Harnessing Using the VIVACE Converter With Passive Turbulence Control , 2011 .

[21]  R. Blevins,et al.  Flow-Induced Vibration , 1977 .

[22]  K. Narendran,et al.  Investigations into efficiency of vortex induced vibration hydro-kinetic energy device , 2016 .

[23]  J. Liao,et al.  A review of fish swimming mechanics and behaviour in altered flows , 2007, Philosophical Transactions of the Royal Society B: Biological Sciences.