Thrust Prediction of an Active Flapping Foil in Waves Using CFD

Kumar, Rupesh; Shin, Hyunkyoung

doi:10.3390/jmse7110396

Cited by 10 publications

(3 citation statements)

References 17 publications

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“…Additionally, Nick et al [16] created a model based on the green sea turtle (Chelonia mydas) and developed a specialized testing rig to uncover the reason for the sea turtle's upstroke strategy, revealing that the utilization of a passive upstroke substantially reduces the animal's drag coefficient. Kumar et al [17] demonstrated that flapping fins, when moving in a compound harmonic motion, can generate thrust, and the propulsive performance is correlated with the frequency. Li et al [18] found an optimal pitch amplitude for flapping propulsion.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of the Effects of Asymmetric Pitching Motion on the Hydrodynamic Propulsion of a Flapping Fin

Wang,

Niu,

et al. 2024

Symmetry

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Aquatic organisms have evolved exceptional propulsion and even transoceanic migrating capabilities, surpassing artificial vessels significantly in maneuverability and efficiency. Understanding the hydrodynamic mechanisms of aquatic organisms is crucial for developing advanced biomimetic underwater propulsion vehicles. Underwater tetrapods such as sea turtles use fins or flippers for propulsion, which exhibit three rotational degrees of freedom, including flapping, sweeping, and pitching motions. Unlike previous studies that often simplify motion kinematics, this study employs a specially designed experimental device to mimic sea turtle fins’ motion and explore the impact of pitching amplitude, asymmetric pitching kinematics, and pausing time on lift and thrust generation. Force transducers and particle image velocimetry techniques are used to examine the hydrodynamic forces and flow field, respectively. It is found that boosting the fin’s pitching amplitude enhances both its lift and thrust efficiency to a certain extent, with a more pronounced effect on thrust performance. Surprisingly, the asymmetrical nature of the pitching angle’s pausing time within one flapping cycle significantly influences the lift and thrust characteristics during sea turtle swimming; extending the pausing time during the forward and upward flapping process improves lift efficiency; and prolonging the pausing time during the downward flapping process enhances thrust efficiency. Furthermore, the mechanism for high lift and thrust efficiency is revealed by examining the vortices shed from the fin during different motion kinematics. This research contributes to a more comprehensive understanding of the fin’s hydrodynamic characteristic, providing insights that can guide the design of more efficient biomimetic underwater propulsion systems.

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Section: Introductionmentioning

confidence: 99%

An Experimental Study of the Effects of Asymmetric Pitching Motion on the Hydrodynamic Propulsion of a Flapping Fin

Wang,

Niu,

et al. 2024

Symmetry

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“…Lagopoulos et al [ 25 ] revealed that increasing the aspect ratio can improve thrust coefficients and thrust augmentation by using a three-dimensional numerical simulation method. Kumar et al [ 26 ] used the fluid module of the ANSYS software to calculate the thrust generated by the active flapping motion in short waves. The results show that an active flapping-foil can effectively convert wave energy into short wave propulsion energy, and the thrust is related to the frequency of the flapping-foil.…”

Section: Introductionmentioning

confidence: 99%

Effect of Frequency–Amplitude Parameter and Aspect Ratio on Propulsion Performance of Underwater Flapping-Foil

Ding,

Chen,

Zhu

et al. 2024

Biomimetics

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The propulsion system is the core component of unmanned underwater vehicles. The flapping propulsion method of marine animals’ flippers, which allows for flexibility, low noise, and high energy utilization at low speeds, can provide a new perspective for the development of new propulsion technology. In this study, a new experimental flapping propulsion apparatus that can be installed in both directions has been constructed. The guide rail slider mechanism can achieve the retention of force in the direction of movement, thereby decoupling thrust, lift, and torque. Subsequently, the motion parameters of frequency–amplitude related to the thrust and lift of a bionic flapping-foil are scrutinized. A response surface connecting propulsion efficiency and these motion parameters is formulated. The highest efficiency of the flapping-foil propulsion is achieved at a frequency of 2 Hz and an amplitude of 40°. Furthermore, the impact of the installation mode and the aspect ratio of the flapping-foil is examined. The reverse installation of the swing yields a higher thrust than the forward swing. As the chord length remains constant and the span length increases, the propulsive efficiency gradually improves. When the chord length is extended to a certain degree, the propulsion efficiency exhibits a parabolic pattern, increasing initially and then diminishing. This investigation offers a novel perspective for the bionic design within the domain of underwater propulsion. This research provides valuable theoretical guidance for bionic design in the underwater propulsion field.

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“…Tian et al found, through experiments, that the position of the pitching fulcrum of the pitching hydrofoil had a considerable influence on the evolution of the wake vortex of the hydrofoil [13]. In addition, in terms of applications, they have been widely used in underwater thrusters [14], gliders [15,16], energy harvesting devices [17][18][19], and valveless piezoelectric pumps [20,21]. In addition, in order to explore ways of achieving improved hydrodynamic performance of hydrofoils, research on the use of a flapping mode in hydrofoils is an indispensable part.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of the Hydrodynamic Performance of Arc and Linear Flapping Hydrofoils

et al. 2023

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In order to improve the hydrodynamic performance of flapping hydrofoils and solve the problem of insufficient hydrodynamic force in plain river network areas, in this study, we consider the more realistic swing of fish tails and propose an arc flapping method, the coupled motion of which has three degrees of freedom: heave, pitch, and lateral displacement. Two flapping methods, positive arcs and negative arcs, were derived on the basis of the lateral displacement direction. By using the finite volume method (FVM) and overlapping grid technology, a numerical simulation was conducted to compare and analyze the pumping performance of three types of flapping hydrofoil, namely, linear, positive arcs, and negative arcs, in order to further provide guidance for the structural optimization of bionic pumping devices. The results showed that the wake vortex structures of the three flapping modes all had anti-Kármán vortex streets, but the wake vortex of linear flapping deflected upward, and the wake vortex of positive arc flapping tended to be further away in the flow field. In one cycle, thrust was always generated by the positive arc flapping hydrofoil and the linear flapping hydrofoil, but the thrust coefficient curve of the positive arc flapping hydrofoil was more stable than that of the linear flapping hydrofoil, and the peak value was reduced by 46.5%. In addition, under the conditions of a flow rate of 750 L·s−1 and an average head of 0.006 m, the pumping efficiency of the positive arc flapping hydrofoil reached 35%, thus showing better pumping performance than the traditional linear flapping hydrofoil under conditions with ultra-low head.

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Thrust Prediction of an Active Flapping Foil in Waves Using CFD

Cited by 10 publications

References 17 publications

An Experimental Study of the Effects of Asymmetric Pitching Motion on the Hydrodynamic Propulsion of a Flapping Fin

An Experimental Study of the Effects of Asymmetric Pitching Motion on the Hydrodynamic Propulsion of a Flapping Fin

Effect of Frequency–Amplitude Parameter and Aspect Ratio on Propulsion Performance of Underwater Flapping-Foil

Comparative Analysis of the Hydrodynamic Performance of Arc and Linear Flapping Hydrofoils

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