Hydrokinetic energy conversion using flow induced oscillations of single-cylinder with large passive turbulence control

2022 ◽  
Vol 308 ◽  
pp. 118380
Author(s):  
Ningyu Li ◽  
Hongrae Park ◽  
Hai Sun ◽  
Michael M. Bernitsas
Keyword(s):  
Energy Conversion ◽  
Turbulence Control ◽  
Single Cylinder ◽  
Hydrokinetic Energy ◽  
Passive Turbulence Control

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.

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.

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.

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.

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