Flow-energy harvesting using a fully passive flapping foil: A guideline on design and operation

2021 ◽  
Vol 197 ◽  
pp. 106323
Author(s):  
Fuwang Zhao ◽  
M.N. Mumtaz Qadri ◽  
Zhaokun Wang ◽  
Hui Tang
Keyword(s):  
Energy Harvesting ◽  
Flapping Foil ◽  
Flow Energy

Optimal frequency for flow energy harvesting of a flapping foil

2011 ◽  
Vol 675 ◽  
pp. 495-517 ◽  
Author(s):  
QIANG ZHU
Keyword(s):  
Energy Harvesting ◽  
Vortex Shedding ◽  
Leading Edge ◽  
Energy Extraction ◽  
Flapping Foil ◽  
Flow Energy ◽  
Performance Point ◽  
High Efficient ◽  
Harvesting Efficiency ◽  
Energy Harvesting Efficiency

Inspired by the correlation between the propulsion efficiency of a flapping foil propeller and stability of the wake behind it (which leads to the optimal Strouhal number for propulsion), we numerically simulated a heaving/pitching foil in energy harvesting regime, and investigated the relation between wake stability and the energy harvesting efficiency. The base flow is computed using a Navier–Stokes algorithm and the stability analysis is performed via the Orr–Sommerfeld equation. The wake is found to be convectively unstable and the frequency of the most unstable mode fw is determined. The case when fw ~ f coincides with maximum energy harvesting efficiency of the system (f is the frequency of foil oscillation), suggesting that flow energy extraction is closely related to efficient evolution of the wake. This occurs at a frequency of f ~ 0.15 (f is normalized by the chord length and the flow speed), under the constraint that there is significant vortex shedding from the leading edge at sufficiently large effective angles of attack. Indeed, this ‘foil–wake resonance’ is usually associated with multi-vortex shedding from the leading edge. Furthermore, detailed examination of energy extractions from the heaving and the pitching motions indicates that near the optimal performance point the average energy extraction from the pitching motion is close to zero. This suggests the feasibility of achieving high-efficient energy harvesting through a simple fully passive system we proposed earlier in which no activation is needed.

Optimal Leading Edge Vortex Formation of a Flapping Foil in Energy Harvesting Regime

2017 ◽  
Author(s):  
Firas F. Siala ◽  
Alexander D. Totpal ◽  
James A. Liburdy
Keyword(s):  
Energy Harvesting ◽  
Vortex Formation ◽  
Leading Edge ◽  
Flux Analysis ◽  
Leading Edge Vortex ◽  
Flapping Foil ◽  
Flow Energy ◽  
Edge Vortex ◽  
Formation Number ◽  
Harvesting Regime

An experimental investigation is conducted to study the leading edge vortex (LEV) evolution of a simultaneously heaving and pitching foil operating in the energy harvesting regime. Two dimensional particle image velocimetry measurements are collected in a wind tunnel at reduced frequencies of k = fc/U = 0.05–0.20. Vorticity flux analysis is performed to calculate the constant C in the vortex formation number equation proposed by J. O. Dabiri [1], and it is shown that for a flapping foil operating in the energy harvesting regime, this constant is approximately equal to 1.33. We demonstrate that the optimal LEV formation number (T̂max ≈ 4) is achieved at k = 0.11, which is well within the range of optimal reduced frequency for energy harvesting applications (k = 0.1–0.15). This suggests that the flow energy extraction is closely related to the efficient evolution process of the LEV.

Mode coupling and flow energy harvesting by a flapping foil

2009 ◽  
Vol 21 (3) ◽  
pp. 033601 ◽  
Author(s):  
Qiang Zhu ◽  
Zhangli Peng
Keyword(s):  
Energy Harvesting ◽  
Mode Coupling ◽  
Flapping Foil ◽  
Flow Energy

scholarly journals A Model for Performance Estimation of Flapping Foil Operating as Biomimetic Stream Energy Device

2020 ◽  
Vol 9 (1) ◽  
pp. 21
Author(s):  
Iro E. Malefaki ◽  
Kostas A. Belibassakis
Keyword(s):  
Vertical Axis ◽  
Flow Speed ◽  
Performance Estimation ◽  
Speed Ratio ◽  
Power Extraction ◽  
Flapping Foil ◽  
Flow Energy ◽  
Novel Concept ◽  
Angular Oscillations ◽  
Energy Converters

During the recent period intensive research has focused on the advancement of engineering and technology aspects concerning the development and optimization of wave and current energy converters driven by the need to increase the percentage of marine renewable sources in the energy-production mix, particularly from offshore installations. Most stream energy-harvesting devices are based on hydro-turbines, and their performance is dependent on the ratio of the blade-tip speed to incident-flow speed. As the oncoming speed of natural-occurring currents varies randomly, there is a penalty for the latter device’s performance when operating at non-constant tip-speed ratio away from the design value. Unlike conventional turbines that are characterized by a single degree of freedom rotating around an axis, a novel concept is examined concerning hydrokinetic energy converters based on oscillating hydrofoils. The biomimetic device includes a rotating, vertically mounted, biomimetic wing, supported by an arm linked at a pivot point on the mid-chord. Activated by a controllable self-pitching motion the system performs angular oscillations around the vertical axis in incoming flow. In this work, the performance of the above flapping-foil, biomimetic flow energy harvester is investigated by application of a semi-3D model based on unsteady hydrofoil theory and the results are verified by comparison to experimental data and a 3D boundary element method based on vortex rings. By systematical application of the model the power extraction and efficiency of the system is presented for various cases including different geometric, mechanical, and kinematic parameters, and the optimal performance of the system is determined.

Hybrid piezoelectric-inductive flow energy harvesting and dimensionless electroaeroelastic analysis for scaling

2013 ◽  
Vol 102 (4) ◽  
pp. 044101 ◽  
Author(s):  
J. A. C. Dias ◽  
C. De Marqui ◽  
A. Erturk
Keyword(s):  
Energy Harvesting ◽  
Flow Energy

scholarly journals An Experimental Investigation of a Passively Flapping Foil in Energy Harvesting Mode

2019 ◽  
Vol 12 (5) ◽  
pp. 1547-1561 ◽  
Author(s):  
M. N. Mumtaz Qadri ◽  
A. Shahzad ◽  
F. Zhao ◽  
H. Tang ◽  
◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Energy Harvesting ◽  
Flapping Foil
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