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- Journal Article:
Anevlavi and Belibassakis
Much work has been done over the past years to obtain a better understanding, predict and alleviate the effects of cavitation on the performance of lifting surfaces for hydrokinetic turbines and marine propellers. Lifting-surface sheet cavitation, when addressed as a free-streamline problem, can be predicted up to a desirable degree of accuracy using numerical methods under the assumptions of…
- Journal Article:
Han et al.
Tidal energy has attracted great attention due to its massive potential and eco-friendly nature. Performance of ducted turbines used in tidal energy conversion is significantly influenced by tip clearance and associated leakage flow. In this work, a method of variable-depth (VD) groove is developed to suppress the tip leakage vortex (TLV) and the tip leakage vortex cavitation (TLVC) around a…
- Journal Article:
Chen et al.
Bio-inspired flapping hydrofoils can be used for propulsion or energy extraction, which has aroused the interest of many scholars. This paper experimentally and numerically studies the propulsion of semi-active hydrofoils used for wave glider. For NACA 0012 foil section, heave amplitude h0 = 1.0 chord, Reynolds number Re=2×104, a series of experiments were conducted. We…
- Journal Article:
Zeng et al.
To understand how cavitation affects underwater structure's vibration characteristics, an experiment on a vibrating hydrofoil is designed to quantitatively measure the flow-induced vibration, added mass, and hydrodynamic damping ratio in cavitating flow. The reliability of the experimental devices was verified, and the maximum cavity length and cavitation Strouhal number were in agreement with…
- Journal Article:
Boudreau et al.
Due to the inherent complexity of the mechanisms needed to prescribe the heave and the pitch motions of optimal flapping-foil turbines, several research groups are now investigating the potential of using unconstrained motions. The amplitude, the phase and the frequency of such passive motions are resulting from the interaction of the foil with the flow and its elastic supports, namely springs…
- Journal Article:
Boudreau et al.
Experiments were conducted to assess the performance of a fully-passive flapping-foil hydrokinetic turbine for which the self-induced and self-sustained blade motions are resulting from the interaction between the blade’s elastic supports (springs and dampers) and the flow field. Previous numerical studies have shown that such a turbine can extract a substantial amount of energy from the flow…
- Journal Article:
Xu and Xu
The energy extraction of two flapping foils with tandem configurations has been studied based on velocity potential theory. The interactions of the hind foil and the vortices of the fore foil with typical oscillatory motions are investigated. The global phase shift, which combines the longitudinal distance and the phase shift of the motions of the two foils, is introduced as the indicating…
- Journal Article:
Zhu et al.
Flapping wing structures have drawn increasing attention for harvesting energy from flowing fluids. This work proposes the application of an adaptive Gurney flap to the trailing end of a flapping wing foil, which actively adjusts the position of a single Gurney flap to be consistently employed on the foil pressure side. The transient two-dimensional numerical simulations are conducted to…
- Journal Article:
Siala and Liburdy
This study experimentally investigates the energy harvesting capabilities of an oscillating wing with a passively actuated trailing edge. The oscillation kinematics are composed of a combined heaving and forward pitching motions, where the pitching axis is well behind the wing center of mass. Passive actuation is attained by connecting the trailing edge with the wing body using a torsion rod.…
- Journal Article:
Ma et al.
The hydrokinetic turbine, using an oscillating foil to extract tidal energy, offers an obvious advantage in shallow water. The software Fluent is used to solve the 2D unsteady incompressible Navier-Stokes equations around an oscillating foil with computations performed with using NACA0015 foil. The parameter µx which indicates the oscillation frequency ratio between the…
- Journal Article:
Ma et al.
The generators using oscillating foil to extract tidal energy have obvious advantages in shallow water. To get rid of the complicated control system, we proposed a hydraulic system to couple dual foils and realize the self-sustained oscillation motion of the foil. The coupling equations related to the foils' motion and hydrodynamic are established. Computations are performed using the software…
- Journal Article:
Xiao et al.
A non-sinusoidal trajectory profile is proposed for the oscillating hydrofoil in the energy generators instead of conventional sinusoidal plunging/pitching motions to seek better energy extraction performance. The novel profile is achieved by combining a specially designed trapezoidal-like pitching motion with a sinusoidal plunging motion and investigated numerically on its output energy…
- Journal Article:
Wu et al.
A numerical investigation on the power extraction of a pitching-motion-activated flapping foil near solid walls is performed by using an immersed boundary-lattice Boltzmann method in this study. The flapping motions of the foil include a forced pitching component and an induced plunging component. The foil is placed either near a solid wall or between two parallel plane walls. Compared to…
- Conference Paper:
Usoh et al.
A non-profiled (rectangular) plate section was investigated for its effect on the performance of a flapping wing turbine for power generation. The plate was subjected to laminar flow conditions having a steady free stream flow (Reynolds number Re 1100); while flapping with prescribed sinusoidal pitching and plunging kinematics. Results of numerical simulation give a power efficiency…
- Conference Paper:
Simpson et al.
We demonstrate experimentally that flapping foils within an oncoming stream can efficiently extract energy from the flow, thus offering an attractive, alternative way for energy production. The greatest promise for flapping foils is to use them in unsteady and turbulent flow, where their own unsteady motion can be controlled to maximize energy extraction. The foils in this study perform a…
- Conference Paper:
Simpson et al.
Work with fish has shown their ability to extract energy from unsteady flows and vortical structures. We demonstrate experimentally that foils performing a sinusoidal sway (heave) and yaw (pitch) motion, similar to a fish, with continuously controlled parameters such as yaw amplitude, Strouhal number, and phase angle between sway and yaw, can efficiently extract energy from unsteady flows.…
- Thesis:
Semler
The objective of this project was to construct and test a device that can transform fluid flow into the continuous oscillatory linear motion of a hydro/airfoil. This device may be used to generate power from a renewable energy source such as tidal flow or wind power. The device was constructed in the NPS machine shop. It consisted of a flat plate that was mounted on two rail guides such that…
- Journal Article:
Kinsey and Dumas
Three-dimensional hydrodynamic losses are assessed in this investigation for a foil oscillating sinusoidally in a combined heave and pitch motion with large amplitudes. Simulations are performed using a unsteady Reynolds-Averaged-Navier-Stokes (URANS) solver on an oscillating foil in a power-extraction mode; thus acting as a hydrokinetic turbine at high Reynolds number. Foils of various aspect…
- Journal Article:
Kinsey and Dumas
A numerical investigation based on 2D URANS simulations is performed in order to seek an optimal spatial configuration for two oscillating foils within a hydrokinetic turbine. The objective of the study is to maximize the power extraction efficiency of the turbine. Tandem spatial configurations are considered because in such arrangement both hydrofoils are sharing the same flow window, which…
- Journal Article:
Kinsey and Dumas
A wing that is heaving and pitching simultaneously may extract energy from an oncoming flow, thus acting as a turbine. The theoretical performance of such a concept is investigated here through unsteady two-dimensional laminar-flow simulations using the commercial…
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