Structural response and energy extraction of a fully passive flapping foil

2017 ◽  
Vol 72 ◽  
pp. 96-113 ◽  
Author(s):  
Zhuo Wang ◽  
Lin Du ◽  
Jisheng Zhao ◽  
Xiaofeng Sun
Keyword(s):  
Structural Response ◽  
Energy Extraction ◽  
Flapping Foil

Study on Performance Enhancement of a Flapping Foil Energy Harvester Using Circulation Control

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Fangrui Shi ◽  
Xiaojing Sun
Keyword(s):  
Extraction Efficiency ◽  
Performance Enhancement ◽  
Net Energy ◽  
Circulation Control ◽  
Energy Extraction ◽  
Injection Port ◽  
Flapping Foil ◽  
Momentum Coefficient ◽  
Reduced Frequency ◽  
Wide Range

Abstract Oscillating motion, an effective way to harvest energy, has gradually become a hotspot in bionic motion research in recent years. Means of improving the energy-extraction efficiency of a flapping foil harvester have long been a focus of researchers. This paper proposes a new flapping foil harvester with circulation control and explores the effects of different parameters on its energy-extraction capacity to improve efficiency and achieve lowest cost. Setting the injection ports on the upper and lower surfaces near the trailing edge of the foil and implementing injection control during motion, the effects of the location of the injection port, pitching amplitude, momentum coefficient, reduced frequency, and jet mode on the circulation control flapping foil are systematically investigated under the condition of a Reynolds number of 13,800. The results show that circulation control can enhance the energy-extraction efficiency of a flapping foil across a wide range of parameters, in which the location of the injection port and momentum coefficient have the most obvious influence on efficiency, followed by pitching amplitude and reduced frequency. In addition, the jet mode is a crucial factor affecting net efficiency. Relative to the constant mode, the triangular mode of circulation control has the lowest energy consumption, and the net energy-extraction efficiency reaches up to 38.77% under a reduced frequency of 0.12, which is 22.24% higher than that of the plain flapping foil.

Inertial effects of the semi-passive flapping foil on its energy extraction efficiency

2015 ◽  
Vol 27 (5) ◽  
pp. 053103 ◽  
Author(s):  
Jian Deng ◽  
Lubao Teng ◽  
Dingyi Pan ◽  
Xueming Shao
Keyword(s):  
Extraction Efficiency ◽  
Energy Extraction ◽  
Inertial Effects ◽  
Flapping Foil

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.

scholarly journals Energy Extraction Performance Improvement of a Flapping Foil by the Use of Combined Foil

2018 ◽  
Vol 11 (6) ◽  
pp. 1651-1663 ◽  
Author(s):  
A. Boudis ◽  
A. Benzaoui ◽  
H. Oualli ◽  
O. Guerri ◽  
A. C. Bayeul-Lainé ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Energy Extraction ◽  
Flapping Foil ◽  
Extraction Performance

scholarly journals A Non-Linear BEM–FEM Coupled Scheme for the Performance of Flexible Flapping-Foil Thrusters

2020 ◽  
Vol 8 (1) ◽  
pp. 56 ◽  
Author(s):  
Dimitra E. Anevlavi ◽  
Evangelos S. Filippas ◽  
Angeliki E. Karperaki ◽  
Kostas A. Belibassakis
Keyword(s):  
Flexural Rigidity ◽  
Structural Response ◽  
Elastic Response ◽  
Thin Plates ◽  
Design Parameters ◽  
Design Assessment ◽  
Flapping Foil ◽  
Propulsive Performance ◽  
Non Linear ◽  
And Control

Recent studies indicate that nature-inspired thrusters based on flexible oscillating foils show enhanced propulsive performance. However, understanding the underlying physics of the fluid–structure interaction (FSI) is essential to improve the efficiency of existing devices and pave the way for novel energy-efficient marine thrusters. In the present work, we investigate the effect of chord-wise flexibility on the propulsive performance of flapping-foil thrusters. For this purpose, a numerical method has been developed to simulate the time-dependent structural response of the flexible foil that undergoes prescribed large general motions. The fluid flow model is based on potential theory, whereas the elastic response of the foil is approximated by means of the classical Kirchhoff–Love theory for thin plates under cylindrical bending. The fully coupled FSI problem is treated numerically with a non-linear BEM–FEM scheme. The validity of the proposed scheme is established through comparisons against existing works. The performance of the flapping-foil thrusters over a range of design parameters, including flexural rigidity, Strouhal number, heaving and pitching amplitudes is also studied. The results show a propulsive efficiency enhancement of up to 6% for such systems with moderate loss in thrust, compared to rigid foils. Finally, the present model after enhancement could serve as a useful tool in the design, assessment and control of flexible biomimetic flapping-foil thrusters.

Numerical investigation of the power extraction mechanism of flapping foil tidal energy harvesting devices

2018 ◽  
Vol 30 (2) ◽  
pp. 193-211 ◽  
Author(s):  
Maryam Pourmahdavi ◽  
Mohammad Naghi Safari ◽  
Shahram Derakhshan
Keyword(s):  
Energy Harvesting ◽  
Stokes Equations ◽  
Critical Role ◽  
Pressure Coefficient ◽  
Leading Edge ◽  
Energy Extraction ◽  
Leading Edge Vortex ◽  
Power Extraction ◽  
Flapping Foil ◽  
Edge Vortex

The flapping foil hydrokinetics turbine is a new method to generate energy from incoming flow field. The numerical simulations have been performed computationally by using two-dimensional unsteady Reynolds-averaged Navier–Stokes equations. It was found that the maximum energy efficiency reached about 35.2% when the reduced frequency was 0.11; at this time, the foil experienced a light dynamic stall and two opposite-sign vorticities were shed from the foil per half of the cycle. This report also studied the energy extraction performance of flapping foil device and the correlation between the foil kinematic parameters and the flow fields around it at actual operating Reynolds number comprehensively. In addition, the vortex variation and the pressure coefficient distribution along the foil’s surface were used to demonstrate the mechanism of flapping foil energy generation turbine. The creation and shedding of the leading edge vortex played the critical role in energy transformation between the flow fluid and energy harvesting systems. Therefore, if the timing of the leading edge vortex generation and shedding is controlled, the energy extraction efficiency can be increased considerably.

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