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.

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

2006 ◽  
Author(s):  
Michael M. Bernitsas ◽  
Y. Ben-Simon ◽  
Kamaldev Raghavan ◽  
E. M. H. Garcia
Keyword(s):  
Reynolds Number ◽  
Power Efficiency ◽  
High Efficiency ◽  
Early Stage ◽  
Water Channel ◽  
Clean Energy ◽  
Low Velocity ◽  
Stage Of Development ◽  
Vortex Induced Vibrations ◽  
The University

The 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 (Vortex Induced Vibrations Aquatic Clean Energy) were introduced in our previous paper. In its simplest form, a VIVACE modulo consists of a single rigid cylinder mounted on elastic supports and connected to a Power Take Off (PTO) system. The cylinder is placed in a steady unidirectional current and excited in 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 its efficiency, and calculate basic benchmarking measures such as energy density. 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 lab, 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 efficiency achieved was ηPeak = 0.308; the corresponding integrated power efficiency in that particular test was ηVIVACE = 0.22 with theoretical upper limit based on measurements of ηUL-VIVACE = 0.3663. Such a high efficiency was achieved even at the low velocity U = 0.840m/sec = 1.63knots.

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.

scholarly journals Centre of Agri-Knowledge – a Web-Based Integration of Information and Decision Support Systems for Agriculture

2006 ◽  
pp. 64-66
Author(s):  
Tamás Dövényi-Nagy
Keyword(s):  
Early Stage ◽  
Eastern Region ◽  
Web Based ◽  
Internet Technologies ◽  
Internet Portal ◽  
Internet Communities ◽  
Stage Of Development ◽  
Agricultural Sciences ◽  
E Learning ◽  
The University

The University Debrecen Centre of Agricultural Sciences acts as the centre and co-ordinator of agrarian higher education and consultation in the eastern region of Hungary. New internet technologies afford new chances to accomplish the institute’s mission to develop agriculture, environment and countryside in the area. As the main framework of integrated e-learning, e-business and research in the agrifood sector the development of an internet portal, the „Centre of Agri-knowledge” (CAK) has been started in the recent past.To support our students and education, to stay continuous in touch with our agricultural engineers we consider very important to build internet communities, where students, farmers, traders and researchers can share their knowledge and experience.In Europe same as in Hungary agriportals born and disappear continuously. Although CAK is still in its early stage of development, its comprehensiveness, professional backend and the experience of the Centre of Agricultural Sciences guarantee a new standard of online services in the Hungarian agrifood sector

Two Degrees of Freedom Vortex-Induced Vibration Responses With Zero Mass and Damping at Low Reynolds Number

2013 ◽  
Author(s):  
Kintak Raymond Yu ◽  
Alexander Hay ◽  
Dominique Pelletier ◽  
Simon Corbeil-Létourneau ◽  
Shahin Ghasemi ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Parameter Space ◽  
Degrees Of Freedom ◽  
Low Reynolds Number ◽  
Mass Ratio ◽  
Vortex Induced Vibration ◽  
Two Degrees Of Freedom ◽  
Zero Mass ◽  
Vortex Induced Vibrations ◽  
Low Reynolds

Vortex-induced vibration is an important phenomenon for offshore engineering. For applications like the piping in the deep water oil exploration projects, the mass ratios can be of order of one [1]. Hence, there is a practical need to understand the effects of low mass ratio on vortex-induced vibrations to enhance design safety. The main purpose of this study is to numerically explore the two degrees of freedom (transverse and streamwise) responses of vortex-induced vibrations of a cylinder at low Reynolds number for the limiting case of zero mass ratio and zero damping. We aim to characterize the responses. In particular, we focus on determining the maximum amplitude values. It is a continuation from the work of Etienne and Pelletier who studied such behaviors at very low Reynolds number (Re < 50) [2]. We investigate the responses in the following parameter space: Reynolds number (75 ≤ Re ≤ 175), reduced velocity (5.0 ≤ Ur ≤ 11.0) and mass ratio (m* = {0, 0.1, 1}) with a fully coupled fluid-structure interaction numerical model based on the finite element method. Our results are generally in accordance with those from previous works for the displacement trajectories, force phase diagram, and the trends in frequency response and oscillation amplitude. The maximum transverse amplitude is found to be around 0.9 in the studied parameter space. In particular, with zero mass ratio, the maximum transverse amplitude starts to occur at values of reduced velocity higher than 6.5 for Reynolds number larger than 150. This is in contrast to the results of Etienne and Pelletier [2] who found that the maximum transverse amplitude always occurs at the reduced velocity of 6.5 for Reynolds number less than 50. Furthermore, with zero mass ratio, the maximum transverse amplitude increases when the Reynolds number increases. This behavior differs from what was suggested by Williamson and Govardhan [3] for a cylinder oscillating only in the transverse direction at Reynolds numbers in the range of 85 to 200. They found that the Reynolds number has no influence on the maximum transverse amplitude. We do not notice any response branching in this parameter space. However, the results in the present work clearly consist of two distinct characteristics. This indicates that the investigated mass ratio values encompass the critical mass ratio; whose value is estimated to be around 0.1 to 0.2.

VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow

2006 ◽  
Author(s):  
Michael M. Bernitsas ◽  
Kamaldev Raghavan ◽  
Y. Ben-Simon ◽  
E. M. H. Garcia
Keyword(s):  
Renewable Energy ◽  
Vortex Shedding ◽  
Life Cycle Cost ◽  
High Efficiency ◽  
Clean Energy ◽  
High Energy ◽  
High Energy Density ◽  
Vortex Induced Vibration ◽  
Wide Range ◽  
River Current

Any device aiming to harness the abundant clean and renewable energy from ocean and other water resources in the USA must have high energy density, be unobtrusive, have low maintenance, be robust, meet life cycle cost targets, and have a 10–20 year life. The VIVACE (Vortex Induced Vibration Aquatic Clean Energy) Converter — invented by Bernitsas & Raghavan and patented through the University of Michigan — satisfies those criteria. It converts ocean/river current kinetic energy to electricity using VIV successfully and efficiently for the first time. VIVACE is based on the simple idea of maximizing rather than spoiling vortex shedding and exploiting rather than suppressing VIV. It introduces optimal damping for energy conversion while maintaining VIV over a broad range of vortex shedding synchronization. VIV occurs over very broad ranges of Reynolds (Re) number. Only two transition regions suppress VIV. Thus, even from currents as slow as 0.25m/sec, VIVACE can extract energy with high efficiency making ocean/river current energy a more accessible and economically viable resource. In this paper, the underlying concepts of the VIVACE Converter are discussed. The designs of the physical model and lab prototype are presented. A mathematical model is developed and design particulars for a wide range of application scales are calculated. Experimental measurements on the lab prototype are reported in the sequel paper and used here for preliminary benchmarking.

Enhancement of High Damping VIV Through Roughness Distribution for Energy Harnessing at 8×103 < Re < 1.5×105

2008 ◽  
Author(s):  
Kamaldev Raghavan ◽  
Michael M. Bernitsas
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Renewable Energy ◽  
Clean Energy ◽  
Reynolds Numbers ◽  
Experimental Facility ◽  
Energy Converter ◽  
High Lift ◽  
Energy Harnessing

Vortex Induced Vibration (VIV) of a circular cylinder in a steady flow is enhanced using distributed surface roughness. VIV enhancement is needed in harnessing clean and renewable energy from ocean/river currents using the VIVACE (VIV for Aquatic Clean Energy) Converter (Bernitsas et al. 2006a, 2006b; Raghavan et al. 2007). High damping is mandatory in energy harnessing and higher Reynolds numbers are required to reach the high lift TrSL3 regime. Roughness is added to the surface of the cylinder in the form of sandpaper strips to achieve three goals: (1) Trip separation in a controlled manner. (2) Fully correlate the flow regardless of the Reynolds number regime. (3) Energize the boundary layer, thus inducing higher vorticity and circulation and consequently lift. Our experiments show that it is possible to achieve all three goals and reach VIV amplitudes of 2.1 to 2.7 diameters under high damping. The range of synchronization increased dramatically but its end was not observed within the capabilities of our experimental facility.

VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Michael M. Bernitsas ◽  
Kamaldev Raghavan ◽  
Y. Ben-Simon ◽  
E. M. H. Garcia
Keyword(s):  
Renewable Energy ◽  
Vortex Shedding ◽  
Life Cycle Cost ◽  
Clean Energy ◽  
High Energy ◽  
High Energy Density ◽  
Vortex Induced Vibration ◽  
Wide Range ◽  
River Current ◽  
Laboratory Prototype

Any device aiming to harness the abundant clean and renewable energy from ocean and other water resources must have high energy density, be unobtrusive, have low maintenance, be robust, meet life cycle cost targets, and have a 10–20year life. The vortex induced vibration aquatic clean energy (VIVACE) converter—invented by Bernitsas and Raghavan, patent pending through the University of Michigan—satisfies those criteria. It converts ocean/river current hydrokinetic energy to a usable form of energy such as electricity using VIV successfully and efficiently for the first time. VIVACE is based on the idea of maximizing rather than spoiling vortex shedding and exploiting rather than suppressing VIV. It introduces optimal damping for energy conversion while maintaining VIV over a broad range of vortex shedding synchronization. VIV occurs over very broad ranges of Reynolds (Re) number. Only three transition regions suppress VIV. Thus, even from currents as slow as 0.25m∕s, VIVACE can extract energy with high power conversion ratio making ocean/river current energy a more accessible and economically viable resource. In this paper, the underlying concepts of the VIVACE converter are discussed. The designs of the physical model and laboratory prototype are presented. A mathematical model is developed, and design particulars for a wide range of application scales are calculated. Experimental measurements on the laboratory prototype are reported in the sequel paper and used here for preliminary benchmarking.

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.

scholarly journals Vortex-induced vibration analysis of viscoelastically mounted rigid circular cylinders in cross-flow at a moderate Reynolds number

2017 ◽  
Vol 24 (13) ◽  
pp. 2688-2700 ◽  
Author(s):  
A.M.G. de Lima ◽  
B.S.C. da Cunha ◽  
A.R. da Silva ◽  
L.F.F. Rodovalho
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Circular Cylinders ◽  
Engineering Practice ◽  
Viscoelastic Materials ◽  
Engineering Structures ◽  
Viscoelastic System ◽  
Vortex Induced Vibration ◽  
Vortex Induced Vibrations ◽  
Moderate Reynolds Number

The vortex-induced vibrations may have disastrous effects in engineering practice, affecting significantly the durability, reliability and safety of engineering structures. This is a reason for which a great deal of effort has been dedicated to the proposition of control strategies to deal with the vortex-induced vibration problem. However, few works have proposed the use of viscoelastic materials to suppress the vibrations induced by vortex shedding, which motivates the present study. Here, the immersed boundary method combined with the virtual physical model is used to investigate the dynamics of a viscoelastically-mounted rigid cylinder in a fluid flow under transverse oscillations induced by vortex shedding. A straightforward time-domain modeling procedure of immersed viscoelastic system by using a four-parameter fractional derivative model is proposed. After the theoretical aspects, numerical tests are performed to investigate the vortex-induced oscillations and flow characteristics of the immersed viscoelastic system at Reynolds number 10,000 for a range of reduced velocity and temperature for two values of mass ratios. The results demonstrate the interest in using viscoelastic materials to mitigate the vortex-induced vibrations.

Webscapes: An academic vision for Digital Humanities Projects on the web

Book 2 0 ◽  
2014 ◽  
Vol 4 (1) ◽  
pp. 121-141
Author(s):  
Bernard Robin ◽  
Sara McNeil
Keyword(s):  
Collaborative Design ◽  
Digital Humanities ◽  
Early Stage ◽  
Design Development ◽  
Non Profit ◽  
University Of Houston ◽  
Stage Of Development ◽  
Community Stakeholders ◽  
The University ◽  
The Web

An overarching goal of the Instructional Technology Programme at the University of Houston has been to help students in our graduate courses learn technology skills by involving them in web-based ‘Digital Humanities Projects’ with local non-profit organizations. In this article, we discuss the benefits and challenges associated with the collaborative design, development and evaluation of real-world projects with community stakeholders serving as clients. Over the past decade, we have developed and used Webscapes, a theoretical model that serves as the framework for the creation of these projects. We define Webscapes as information landscapes, delivered over the web, which include a rich variety of content; challenging, cognitive explorations; intuitive navigation structures; and user-oriented interfaces. We describe the characteristics of the model and include reflections from students and community partners about accomplishments and challenges they faced. We also provide examples and discussion of Webscape projects, several of which have been completed, two that are ongoing and one that is in the early stage of development.

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