Multi-Cylinder Flow-Induced Motions: Enhancement by Passive Turbulence Control at 28,000

2011 ◽  
Author(s):  
Eun Soo Kim ◽  
Michael M. Bernitsas ◽  
R. Ajith Kumar
Keyword(s):  
Clean Energy ◽  
High Amplitude ◽  
Complex Flow ◽  
Turbulence Control ◽  
Hydrokinetic Energy ◽  
Marine Renewable Energy ◽  
Parameter Ranges ◽  
Cylinder Flow ◽  
Passive Turbulence Control ◽  
Center Distance

The VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) Converter was introduced at OMAE2006 as a single, smooth, circular-cylinder module. The hydrodynamics of VIVACE is being improved continuously to achieve higher density in harnessed hydrokinetic power. Inter-cylinder spacing and Passive Turbulence Control (PTC) through selectively located roughness are effective tools in enhancement of Flow Induced Motions (FIMs) under high damping for power harnessing. VIVACE Converters consist of multi-cylinder modules. Single cylinders harness energy at high density even in 1knot currents. For downstream cylinders questions are raised on energy availability and sustainability of high-amplitude FIM. Through PTC and inter-cylinder spacing, strongly synergetic FIM of 2/3/4 cylinders is achieved, harnessing hydrokinetic energy with increased footprint density. Two-cylinder smooth/PTC and four-cylinder PTC systems are tested experimentally. Using the “PTC-to-FIM” map developed in previous work at the Marine Renewable Energy Laboratory (MRELab), PTC is applied and cylinder response is measured for the following parameter ranges: In-flow center-to-center distance 1.63•D–5.00•D (D = diameter), transverse center-to-center distance 0.5•D–1.5•,D, Re ∈[28,000–120,000], m* ∈[1.677–1.690], U ∈[0.36m/s–1.45m/s], aspect ratio l/D = 10.29, and m*ζ ∈[0.0283–0.0346]. All experiments are conducted in the Low Turbulence Free Surface Water (LTFSW) Channel of MRELab. Amplitude spectra and broad filed-of-view (FOV) visualization help reveal complex flow structures and cylinder interference undergoing VIV, interference/proximity/wake/soft/hard galloping.

Multicylinder Flow-Induced Motions: Enhancement by Passive Turbulence Control at 28,000

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Eun Soo Kim ◽  
Michael M. Bernitsas ◽  
R. Ajith Kumar
Keyword(s):  
High Amplitude ◽  
Field Of View ◽  
Flow Structures ◽  
Complex Flow ◽  
Turbulence Control ◽  
Marine Renewable Energy ◽  
Amplitude Spectra ◽  
Parameter Ranges ◽  
Passive Turbulence Control ◽  
Center Distance

The VIVACE converter was introduced at OMAE2006 as a single, smooth, circular-cylinder module. The hydrodynamics of VIVACE is being improved continuously to achieve higher density in harnessed hydrokinetic power. Intercylinder spacing and passive turbulence control (PTC) through selectively located roughness are effective tools in enhancement of flow induced motions (FIMs) under high damping for power harnessing. Single cylinders harness energy at high density even in 1 knot currents. For downstream cylinders, questions were raised on energy availability and sustainability of high-amplitude FIM. Through PTC and intercylinder spacing, strongly synergetic FIMs of 2/3/4 cylinders are achieved. Two-cylinder smooth/PTC, and three/four-cylinder PTC systems are tested experimentally. Using the “PTC-to-FIM” map developed in previous work at the Marine Renewable Energy Laboratory (MRELab), PTC is applied and cylinder response is measured for inflow center-to-center distance 2D-5D (D = diameter), transverse center-to-center distance 0.5–1.5 D, Re ε [28,000–120,000], m* ε [1.677–1.690], U ε [0.36–1.45 m/s], aspect ratio l/D = 10.29, and m*ζ ε [0.0283–0.0346]. All experiments are conducted in the low turbulence free surface water (LTFSW) channel of MRELab. Amplitude spectra and broad field-of-view (FOV) visualization help reveal complex flow structures and cylinder interference undergoing VIV, interference/ proximity/wake/soft/hard galloping. FIM amplitudes of 2.2–2.8D are achieved for all cylinders in steady flow for all parameter ranges tested.

Numerical Simulation and Experiments of Flow-Induced Oscillations of Single-Cylinder With Large Passive Turbulence Control

2020 ◽  
Author(s):  
Ningyu Li ◽  
Hongrae Park ◽  
Hai Sun ◽  
Michael M. Bernitsas
Keyword(s):  
Circular Cylinder ◽  
Transition Region ◽  
Amplitude Ratio ◽  
Clean Energy ◽  
High Amplitude ◽  
Limited Attention ◽  
Cylinder Surface ◽  
Turbulence Control ◽  
Single Cylinder ◽  
Passive Turbulence Control

Abstract Passive turbulence control (PTC) is being used in the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan to enhance flow induced oscillations (FIO) of cylinders in the VIVACE (Vortex Induced Vibration for Aquatic Clean Energy) Converter. Large PTC triggers VIV and galloping at lower flow speeds for energy harvesting. Currently, FIO of cylinders with large PTC for high Re has received limited attention and, particularly, the effect of variable PTC height on FIO of cylinders. The vast majority of ocean currents, rivers, and tides are too slow for Marine Hydro Kinetic (MHK) energy technologies to harness it. In order to enhance FIO and to initiate galloping earlier, a circular cylinder is geometrically modified using straight strips placed on the cylinder surface symmetrically PTC strips on the cylinder effectively change the flow properties. In the present study, the FIO of a single-cylinder with large PTC, on end linear-springs, is modelled and simulated using a Fluid-Structure Interaction (FSI) code. Results are verified by corresponding experimental data. Results show that VIV onset occurs at lower Re for large-PTC cylinder in comparison with lower-PTC cylinder. Contrary to smooth cylinders for which the amplitude ratio is small in the transition region between VIV and galloping, application of large PTC leads to high amplitude response in the transition region. The mechanism behind this observation is the further departure of the geometry from the smooth circular cylinder. The latter does not exhibit galloping due to flow and geometric symmetry in all directions. Moreover, in the galloping region, the amplitude ratio increases with the height of PTC. Earlier onset of galloping and enhancement of geometric asymmetry support this observation as well.

Hydrokinetic Energy Harnessing Using the VIVACE Converter With Passive Turbulence Control

2011 ◽  
Author(s):  
Che-Chun Chang ◽  
Michael M. Bernitsas
Keyword(s):  
Turbulent Shear ◽  
Motion Mechanism ◽  
Turbulence Control ◽  
Hydrokinetic Energy ◽  
Turbulent Shear Layer ◽  
Induced Motion ◽  
Layer Flow ◽  
Set Up ◽  
Energy Harnessing ◽  
Passive Turbulence Control

Passive turbulence control (PTC) in the form of selectively applied surface roughness is used on a rigid circular cylinder supported by two end-springs in transverse steady flow. The flow-induced motions are enhanced dramatically reaching the limits of the experimental facility and motion mechanism at amplitude to diameter ratio A/D ≅ 3. In comparison to a smooth cylinder, in the fully turbulent shear layer flow regime at Reynolds number on the order of 100,000, PTC initiates VIV earlier at reduce velocity U* ≅ 4, reduces VIV amplitude depending on damping, and initiates galloping at U* ≅ 10 rather than 20. Thus, back-to-back VIV and galloping are achieved expanding the synchronization range of Flow Induced Motion (FIM) beyond U* ≅ 15 and the capabilities of the experimental set-up. The harnessed horizontal hydrokinetic power increased by a factor of four due to increased velocities in the synchronization range without any adjustment of the motion mechanism particulars.

scholarly journals Computational and Experimental Assessment of Turbulence Stimulation on Flow Induced Motion of a Circular Cylinder

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Omer Kemal Kinaci ◽  
Sami Lakka ◽  
Hai Sun ◽  
Ethan Fassezke ◽  
Michael M. Bernitsas
Keyword(s):  
University Of Michigan ◽  
Amplitude Response ◽  
Turbulence Control ◽  
Marine Renewable Energy ◽  
Vortex Induced Vibrations ◽  
Highly Nonlinear ◽  
Invaluable Tool ◽  
Induced Motion ◽  
The University ◽  
Passive Turbulence Control

Vortex-induced vibrations (VIVs) are highly nonlinear and it is hard to approach the problem analytically or computationally. Experimental investigation is therefore essential to address the problem and reveal some physical aspects of VIV. Although computational fluid dynamics (CFDs) offers powerful methods to generate solutions, it cannot replace experiments as yet. When used as a supplement to experiments, however, CFD can be an invaluable tool to explore some underlying issues associated with such complicated flows that could otherwise be impossible or very expensive to visualize or measure experimentally. In this paper, VIVs and galloping of a cylinder with selectively distributed surface roughness—termed passive turbulence control (PTC)—are investigated experimentally and computationally. The computational approach is first validated with benchmark experiments on smooth cylinders available in the literature. Then, experiments conducted in the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan are replicated computationally to visualize the flow and understand the effects of thickness and width of roughness strips placed selectively on the cylinder. The major outcomes of this work are: (a) Thicker PTC initiates earlier galloping but wider PTC does not have a major impact on the response of the cylinder and (b) The amplitude response is restricted in VIV due to the dead fluid zone attached to the cylinder, which is not observed in galloping.

Flow-Induced Vibration (FIV) and Hydrokinetic Power Conversion of Two Staggered, Low Mass-Ratio Cylinders, With Passive Turbulence Control in the TrSL3 Flow Regime (2.5×104

2017 ◽  
Author(s):  
Wanhai Xu ◽  
Chunning Ji ◽  
Hai Sun ◽  
Wenjun Ding ◽  
Michael M. Bernitsas
Keyword(s):  
Flow Regime ◽  
Total Power ◽  
Mass Ratio ◽  
Flow Induced Vibration ◽  
Turbulence Control ◽  
Hydrokinetic Energy ◽  
Staggered Arrangement ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Passive Turbulence Control

Flow-induced vibration (FIV), primarily vortex-induced vibrations (VIV) and galloping have been used effectively to convert hydrokinetic energy to electricity in model-tests and field-tests by the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan. The developed device, called VIVACE (VIV for Aquatic Clean Energy), harnesses hydrokinetic energy from river and ocean flows. One of the methods used to improve its efficiency of harnessed power efficiency is Passive Turbulence Control (PTC). It is a turbulence stimulation method that has been used to alter FIV of a cylinder in a steady flow. FIV of elastically mounted cylinders with PTC differs from the oscillation of smooth cylinders in a similar configuration. Additional investigation of the FIV of two elastically mounted circular cylinders in staggered arrangement with a low mass ratio in the TrSL3 flow-regime is required and is contributed by this paper. A series of experimental studies on FIV of two PTC cylinders in staggered arrangement were carried out in the recirculating water channel of MRELab. The two cylinders were allowed to oscillate in the transverse direction to the oncoming fluid flow. Cylinders tested have, diameter D = 8.89cm, length L = 0.895m and mass ratio m* = 1.343. The Reynolds number was in the range of 2.5×104<Re<1.2×105, which is a subset of the TrSL3 flow-regime. The center-to-center longitudinal and transverse spacing distances were T/D = 2.57 and S/D = 1.0, respectively. The spring stiffness values were in the range of 400<K<1200N/m. The values of harnessing damping ratio tested were ζharness = 0.04, 0.12, 0.24. For the values tested, the experimental results indicate that the response of the 1st cylinder is similar to a single cylinder; however more complicated vibration of the 2nd cylinder is observed. In addition, the oscillation system of two cylinders with stiffer spring and higher ζharness could initiate total power harness at a larger flow velocity and harness much higher power. These findings are very meaningful and important for hydrokinetic energy conversion.

Envelope of Power Harvested by a Single-Cylinder VIVACE Converter

2015 ◽  
Author(s):  
Jianhui Liu ◽  
Michael M. Bernitsas
Keyword(s):  
Damping Ratio ◽  
Reynolds Numbers ◽  
High Amplitude ◽  
Navier Stokes ◽  
Number Range ◽  
Turbulence Control ◽  
Single Cylinder ◽  
Hydrokinetic Energy ◽  
Grid Interface ◽  
Vortex Induced Vibrations

Flow Induced Motions (FIM) of a single-cylinder VIVACE Converter is investigated using two-dimensional Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with the Spalart-Allmaras turbulence model at Reynolds numbers (30,000 ≤Re≤120,000, 5.50≤U*≤9.85) in the TrSL3 flow regime. Computational results compare very well with experimental data. With implementation of Passive Turbulence Control (PTC), the VIVACE Converter can harness hydrokinetic energy from currents or tides over an expanded range of FIM synchronization, including Vortex Induced Vibrations (VIV) and galloping. The General Grid Interface (GGI) with topological mesh changes is proved to be an effective method for handling high-amplitude FIM response. Within the test Reynolds number range, five regions are clearly observed, including the no-FIM range, the VIV initial branch, the VIV upper branch, transition from VIV to galloping, and galloping. The power envelope calculated based on the CDF simulations for FIM agrees very well with the corresponding power envelope generated based on experiments. The range between VIV and galloping can be eliminated by adjusting the spring-stiffness and the harnessing damping-ratio. This is verified by both experiments and numerical simulation.

RANS Simulation vs. Experiments of Flow Induced Motion of Circular Cylinder With Passive Turbulence Control at 35,000

2011 ◽  
Author(s):  
Wei Wu ◽  
Michael M. Bernitsas ◽  
Kevin Maki
Keyword(s):  
Circular Cylinder ◽  
Amplitude Ratio ◽  
Cylinder Wall ◽  
Turbulence Control ◽  
Induced Motion ◽  
High Reynolds ◽  
Vortex Patterns ◽  
Cylinder Flow ◽  
The University ◽  
Passive Turbulence Control

Two-dimensional RANS equations with the Spalart-Allmaras turbulence model are used to simulate the flow and body kinematics of a rigid circular cylinder mounted on springs, transversely to a steady uniform flow in the high-lift, TrSL3 regime with 35,000<Re<130,000. Passive Turbulence Control (PTC) in the form of selectively distributed surface roughness is used to alter the cylinder Flow Induced Motion (FIM). Simulation is performed by using a solver based on the open source CFD tool OpenFOAM, which solves continuum mechanics problems with a finite volume discretization method. Roughness parameters of PTC are simulated modeling tests conducted in the Marine Renewable Energy Lab (MRELab) of the University of Michigan. The numerical tool is first tested on smooth cylinder in VIV and results are compared with available experimental measurements and RANS simulations. For the cylinder with PTC cases, the sandpaper grit (k) on the cylinder wall is modeled as a rough-wall boundary condition. Two sets of cases with different system parameters (spring constant, damping) are simulated and the results are compared with experimental data measured in the MRELab. The amplitude-ratio curve shows clearly three different branches, including the VIV initial and upper branches and a galloping branch, similar to those observed experimentally. Frequency ratio, vortex patterns, transitional behavior, and lift are also predicted well for PTC cylinders at such high Reynolds numbers.

scholarly journals The Permitting, Licensing and Environmental Compliance Process: Lessons and Experiences within U.S. Marine Renewable Energy

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5048
Author(s):  
Zachary Barr ◽  
Jesse Roberts ◽  
William Peplinski ◽  
Anna West ◽  
Sharon Kramer ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Clean Energy ◽  
Vital Role ◽  
Lessons Learned ◽  
Marine Renewable Energy ◽  
Marine Energy ◽  
Efficiency And Effectiveness ◽  
Practical Experiences ◽  
Permitting Process ◽  
The U.S

The marine renewable energy (MRE; renewable energy captured from waves, tides, ocean currents, the natural flow of water in rivers, and marine thermal gradients, without building new dams or diversions) industry has a vital role in the U.S. clean energy strategy as we progress to meet U.S. electricity and blue economy needs with renewable, domestic energy sources. However, a thorough assessment of the U.S. marine energy permitting process from the viewpoints of both developers that propose projects and regulators that permit them has not been performed. Sharing practical experiences in this new industry is vital to increase the efficiency and effectiveness of the permitting process, identify data and information gaps, develop lessons learned, and advance the industry. This paper is a case study of qualitative findings, lessons learned, and recommendations from guided discussions, workshops, and webinars with both marine renewable energy developers and state and federal regulators that have experience in the permitting process in the U.S.

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