Hydrokinetic Energy Conversion by Flow-Induced Oscillation of Two Tandem-Cylinders of Different Stiffness

2021 ◽  
pp. 1-17
Author(s):  
Wenyong Yuan ◽  
Hai Sun ◽  
Eun Soo Kim ◽  
H Li ◽  
Nicholas Beltsos ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Damping Ratio ◽  
Water Channel ◽  
Great Influence ◽  
Clean Energy ◽  
Shielding Effect ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Energy Harnessing

Abstract The VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) Converter harnesses hydrokinetic energy by enhancing flow-induced oscillations (FIOs) of elastically supported rigid cylinders in a river, tide, or ocean current. The harnessing power depends on the intensity of the oscillation, which is a consequence of the flow-structure interaction. The inflow condition for the downstream (2nd) cylinder is slowed down and perturbed by the upstream (1st) cylinder, due to the shielding effect. Therefore, the optimal structural parameters, i.e., stiffness and damping ratio, for the 2nd cylinder may be different from the 1st cylinder, in terms of energy harnessing. To improve the performance of the VIVACE Converter, a series of experiments are conducted in a recirculating water channel, with various stiffness combinations of two cylinders in tandem. Results show that the stiffness of the 2nd cylinder, K2, does not affect the energy harnessing power in vortex-induced vibration (VIV) occurring at low speeds, because the oscillation of the downstream cylinder in this velocity range is completely dominated by the wake of the upstream cylinder. K2 has a great influence on the harnessing power at higher velocities in the transition region from VIV to galloping and in galloping. Changing K2 onsets and enhances galloping at lower flow velocity and harnesses up to 110% more energy than the case of K1 = K2.

Hydrokinetic Energy Conversion by Flow-Induced Oscillation of Two Tandem-Cylinders of Different Stiffness

2020 ◽  
Author(s):  
Wenyong Yuan ◽  
Hai Sun ◽  
Nicholas Beltsos ◽  
Michael M. Bernitsas
Keyword(s):  
Structural Parameters ◽  
Damping Ratio ◽  
Great Influence ◽  
Clean Energy ◽  
Shielding Effect ◽  
Ocean Current ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Energy Harnessing ◽  
The Impact

Abstract The VIVACE (Vortex-Induced Vibration for Aquatic Clean Energy) Converter harnesses hydrokinetic energy by enhancing flow-induced oscillations (FIOs) of elastically supported rigid cylinders in a river, tide, or ocean current. The harnessing power depends on the intensity of the oscillation, which is a consequence of the flow-structure interaction. The inflow condition for the downstream (2nd) cylinder is slowed down and perturbed by the upstream (1st) cylinder, due to the shielding effect. Therefore, the optimal structural parameters, i.e., stiffness and damping ratio, for the 2nd cylinder may be different from the 1st cylinder, in terms of energy harnessing. To improve the performance of the VIVACE Converter, a series of experiments are conducted in a recirculating water channel, with various stiffness combinations of two cylinders in tandem. Three center-to-center spacings, six damping ratios, and seven combinations of spring stiffness are tested. The stiffness of the 1st cylinder, K1, is 600 N/m or 1,000 N/m, while the stiffness of the 2nd cylinder, K2, varies from 400 N/m to 1,200 N/m in increments of 200N/m. Results show that K2 does not affect the energy harnessing power in vortex-induced vibration (VIV) occurring at low speeds, but has great influence on the harnessing power at higher velocities in the transition region from VIV to galloping and in galloping. Decreasing K2 onsets and enhances galloping at lower flow velocity and harnesses up to 110% more energy than the case of K1 = K2. For K1 = 1,000 N/m, the harnessed power is the same for all the combinations of K1 and K2. The overall performance is best when K1 = K2. As spacing increases, the impact of K2 is diminished as explain by the dependence of power on the amplitude and frequency of cylinder oscillations.

Effect of Bottom Boundary on VIV for Energy Harnessing at 8×103

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
K. Raghavan ◽  
Michael M. Bernitsas ◽  
D. E. Maroulis
Keyword(s):  
Strong Dependence ◽  
Clean Energy ◽  
Reynolds Numbers ◽  
Strong Impact ◽  
University Of Michigan ◽  
Vortex Induced Vibration ◽  
Bottom Boundary ◽  
The University ◽  
Energy Harnessing ◽  
First Time

The concept of extracting energy from ocean/river currents using vortex induced vibration was introduced at the OMAE2006 Conference. The vortex induced vibration aquatic clean energy (VIVACE) converter, implementing this concept, was designed and model tested; VIV amplitudes of two diameters were achieved for Reynolds numbers around 105 even for currents as slow as 1.6 kn. To harness energy using VIV, high damping was added. VIV amplitude of 1.3 diameters was maintained while extracting energy at a rate of PVIVACE=0.22×0.5×pU3DL at 1.6 kn. Strong dependence of VIV on Reynolds number was proven for the first time due to the range of Reynolds numbers achieved at the Low-Turbulence Free Surface Water (LTFSW) Channel of the University of Michigan. In this paper, proximity of VIVACE cylinders in VIV to a bottom boundary is studied in consideration of its impact on VIV, potential loss of harnessable energy, and effect on soft sediments. VIV tests are performed in the LTFSW Channel spanning the following ranges of parameters: Re∊[8×103–1.5×105], m∗∊[1.0–3.14], U∊[0.35–1.15 m/s], L/D∊[6–36], closest distance to bottom boundary (G/D)∊[4−0.1], and m∗ζ∊[0.14–0.26]. Test results show strong impact for gap to diameter ratio of G/D<3 on VIV, amplitude of VIV, range of synchronization, onset of synchronization, frequency of oscillation, hysteresis at the onset of synchronization, and hysteresis at the end of synchronization.

Synergistic Flow-Induced Oscillation of Multiple Cylinders in Harvesting Marine Hydrokinetic Energy

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Mengyu Li ◽  
Christopher C. Bernitsas ◽  
Jing Guo ◽  
Hai Sun
Keyword(s):  
Negative Impact ◽  
Flow Speed ◽  
Shielding Effect ◽  
University Of Michigan ◽  
Hydrokinetic Energy ◽  
Close Proximity ◽  
Marine Hydrokinetic ◽  
The University ◽  
Energy Harnessing

Abstract Flow-induced oscillations/vibrations (FIO/V) of cylinders in tandem can be enhanced by proper in-flow spacing to increase hydrokinetic energy harnessing. In a farm of multiple cylinders in tandem, the effect of interference on harnessing efficiency arises. Three years of systematic experiments in the Marine Renewable Laboratory (MRELab) of the University of Michigan, on an isolated cylinder, and two and three cylinders in tandem have revealed that synergistic FIO can enhance oscillations of cylinders in close proximity. Two cylinders in tandem can harness 2.5–13.5 times the hydrokinetic power of one isolated cylinder. Three cylinders in tandem can harness 3.4–26.4 times the hydrokinetic power of one isolated cylinder. Negative impact on the harnessed energy by multiple cylinders, such as the shielding effect for the downstream cylinder/s, is possible. Specifically for the three-cylinder configuration, at a certain flow speed, the decrease in the power of the middle cylinder can be overcome by adjusting its stiffness and/or damping.

scholarly journals Mechanism Analysis and Parameter Optimization of Mega-Sub-Isolation System

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Xiangxiu Li ◽  
Ping Tan ◽  
Xiaojun Li ◽  
Aiwen Liu
Keyword(s):  
Frequency Ratio ◽  
Seismic Isolation ◽  
Structural Parameters ◽  
Damping Ratio ◽  
Great Influence ◽  
Mechanism Analysis ◽  
Control Performance ◽  
Optimal Frequency ◽  
Working Mechanism ◽  
Isolation System

The equation of motion of mega-sub-isolation system is established. The working mechanism of the mega-sub-isolation system is obtained by systematically investigating its dynamic characteristics corresponding to various structural parameters. Considering the number and location of the isolated substructures, a procedure to optimally design the isolator parameters of the mega-sub-isolation system is put forward based on the genetic algorithm with base shear as the optimization objective. The influence of the number and locations of isolated substructures on the control performance of mega-sub-isolation system has also been investigated from the perspective of energy. Results show that, with increase in substructure mass, the working mechanism of the mega-sub-isolation system is changed from tuned vibration absorber and energy dissipation to seismic isolation. The locations of the isolated substructures have little influence on the optimal frequency ratio but have great influence on the optimal damping ratio, while the number of isolated substructures shows great impact on both the optimal frequency ratio and damping ratio. When the number of the isolated substructures is determined, the higher the isolated substructures, the more the energy that will be consumed by the isolation devices, and with the increase of the number of isolated substructures, the better control performance can be achieved.

The VIVACE Converter: Model Tests at High Damping and Reynolds Number Around 105

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Michael M. Bernitsas ◽  
Y. Ben-Simon ◽  
Kamaldev Raghavan ◽  
E. M. H. Garcia
Keyword(s):  
Reynolds Number ◽  
Renewable Energy ◽  
Early Stage ◽  
Water Channel ◽  
Fluid Flows ◽  
Clean Energy ◽  
Vortex Induced Vibration ◽  
Stage Of Development ◽  
Vortex Induced Vibrations ◽  
The University

The vortex induced vibrations for aquatic clean energy (VIVACE) converter is a new concept to generate clean and renewable energy from fluid flows such as those abundant in oceans, rivers, or other water resources. The underlying concepts for design, scaling, and operation of VIVACE were introduced in Bernitsas et al., 2008, “VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow,” ASME J. Offshore Mech. Arct. Eng., 130(4), p. 041101. In its simplest form, a VIVACE modulo consists of a single rigid cylinder mounted on elastic supports and connected to a power takeoff (PTO) system. The cylinder is placed in a steady unidirectional current and excited in vortex induced vibration (VIV). In this paper, the VIVACE modulo was tested in the Low Turbulence Free-Surface Water Channel of the University of Michigan to demonstrate the concept, generate electricity, measure the power out, and calculate basic benchmarking measures such as energy density. The tests performed were tailored to the particulars of the VIVACE modulo, which dictate that the cylinder operate in VIV under high damping and as high a Reynolds number as possible. At the same time, a broad range of synchronization is required to make VIVACE effective in energy generation in a realistic environment. Due to these requirements, VIV tests have not been performed before in the subspace applicable to the operation of the VIVACE modulo. In the process of extracting fluid kinetic energy and converting it to electricity in the laboratory, for a given set of cylinder-springs-transmission-generator, only the damping used for harnessing electricity was optimized. Even at this early stage of development, for the tested VIVACE modulo, the maximum peak power achieved was Ppeak=0.308×12ρDLL. The corresponding integrated power in that particular test was PVIVACE=0.22×12ρU3DL with theoretical upper limit based on measurements of PUL–VIVACE=0.3663. Such power was achieved at velocity U=0.840m∕s=1.63Kn.

Vortex Induced Vibration for Aquatic Clean Energy

2011 ◽  
Vol 110-116 ◽  
pp. 2117-2117
Keyword(s):  
Clean Energy ◽  
Vortex Induced Vibration ◽  
International Conference ◽  
Asme Journal ◽  
Energy Harnessing

Removed due to plagiarism. Original published: ENHANCEMENT OF HIGH DAMPING VIV THROUGH ROUGHNESS DISTRIBUTION FOR ENERGY HARNESSING AT 8×103 < Re < 1.5×105 Kamaldev Raghavan, Michael M. Bernitsas Proceedings of the ASME 27th International Conference on Offshore Mechanics and Arctic Engineering OMAE2008, June 15-20, 2008, Estoril, Portugal Publihsed By ASME Journal of Offshore Mechanics and Arctic Engineering 041101 Vol. 130, NOVEMBER 2008 Michael M. Bernitsas et al. Published By ASME

Boundaries Influence on the Flow Field Around an Oscillating Sphere

2013 ◽  
Author(s):  
Domenica Mirauda ◽  
Antonio Volpe Plantamura ◽  
Stefano Malavasi
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Boundary Conditions ◽  
Damping Ratio ◽  
Water Channel ◽  
Open Water ◽  
Free Surface Flows ◽  
The Body ◽  
Sphere Diameter ◽  
Oscillating Sphere

This work analyzes the effects of the interaction between an oscillating sphere and free surface flows through the reconstruction of the flow field around the body and the analysis of the displacements. The experiments were performed in an open water channel, where the sphere had three different boundary conditions in respect to the flow, defined as h* (the ratio between the distance of the sphere upper surface from the free surface and the sphere diameter). A quasi-symmetric condition at h* = 2, with the sphere equally distant from the free surface and the channel bottom, and two conditions of asymmetric bounded flow, one with the sphere located at a distance of 0.003m from the bottom at h* = 3.97 and the other with the sphere close to the free surface at h* = 0, were considered. The sphere was free to move in two directions, streamwise (x) and transverse to the flow (y), and was characterized by values of mass ratio, m* = 1.34 (ratio between the system mass and the displaced fluid mass), and damping ratio, ζ = 0.004. The comparison between the results of the analyzed boundary conditions has shown the strong influence of the free surface on the evolution of the vortex structures downstream the obstacle.

Investigating Opto-Electronic Properties of Surface Plasmon Structure for Spectroscopic Applications

2019 ◽  
pp. 216-276
Author(s):  
Pratibha Verma ◽  
Arpan Deyasi
Keyword(s):  
Surface Plasmon ◽  
Incidence Angle ◽  
Structural Parameters ◽  
Metal Layer ◽  
Damping Ratio ◽  
Characteristic Impedance ◽  
Field Enhancement ◽  
Wavelength Dependence ◽  
Allowable Limit ◽  
Layer Medium

This chapter is proposed with an approach to analyze reflectance as a function of negative index material thickness for different parameters under the surface plasmon condition and extended approach towards the field enhancement of electric field as function of incidence angle and transmittance as function of incidence angle has been analyzed. This chapter can reflect the good comparison between 3 layer medium and n layer medium model. Characteristic impedance of MIM surface plasmon structure is analytically calculated considering the effect of both Faraday inductance and kinetic inductance. Effect of metal layer thickness, insulator thickness, and electron density are tailored to observe the impedance variation with frequency. Wavelength dependence of characteristic impedance and quality factor of MIM (metal-insulator-metal) surface plasmon structure is analyzed. Structural parameters and damping ratio of the structure is tuned within allowable limit to analyze the variation after detailed analytical computation.

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