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propulsive performance of a passively flapping plate in a uniform flow

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Journal of Hydrodynamics 2015年第4期27卷 496-501页

作者：韩瑞张杰曹垒陆夕云 State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of Sciences Department of Modern Mechanics University of Science and Technology of China

propulsive performance of a passively flapping plate in a uniform viscous flow has been studied numerically by means of a multiblock lattice Boltzmann method. The passively flapping plate is modeled by a rigid plate with a torsion spring acting about the pivot at the leading-edge of the plate, which is called a lumped-torsional-flexibility model. When the leading-edge is forced to take a vertical oscillation, the plate pitches passively due to the fluid-plate interaction. Based on our numerical simulations, various fundamental mechanisms dictating the propulsive performance, including the forces on the plate, power consumption, propulsive efficiency and vortical structures, have been studied. It is found that the torsional flexibility of the passively pitching plate can improve the propulsive performance. The results obtained in this study provide some physical insights into the understanding of the propulsive behaviors of swimming and flying animals.

关键词： propulsive performance passively flapping plate flapping-based locomotion flexibility effect propulsive efficiency

Kinematic optimization of 2D plunging airfoil motion using the response surface methodology

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第2期13卷 105-120页

作者： Mahmoud MEKADEM Taha CHETTIBI Samir HANCHI Laurent KEIRSBULCK Larbi LABRAGA Fluids Mechanics Laboratory Polytechnic Military SchoolBordj el BahriAlgiers 16045Algeria TEMPO Laboratory University of Valenciennes and Hainaut-Cambresis59313 Valenciennes Cedex 9France Structural Mechnics Laboratory Polytechnic Military SchoolBordj el BahriAlgiers 16045Algeria TEMPO Laboratory University of Valenciennes and Hainaut-Cambresis59313 Valenciennes Cedex 9France

The propulsive efficiency of a plunging NACA0012 airfoil is maximized by means of a simple numerical optimization method based on the response surface methodology （RSM）. The control parameters are the amplitude and the reduced frequency of the harmonic sinusoidal motion. The 2D unsteady laminar flow around the plunging airfoil is computed by solving the Navier-Stokes equations for three Reynolds number values （Re = 3.3× 10^3, 1.1×10^4, and 2.2 × 10^4）. The Nelder-Mead algorithm is used to find the best control parameters leading to the optimal propulsive efficiency over the constructed response surfaces. It is found that, for a given efficiency level and regardless of the considered Re value, it is possible either to obtain high thrust by selecting a high oscillation frequency or to reduce the input power by adopting a low plunging amplitude. Key words： Plunging airfoil, propulsive efficiency, Optimization, Response surface methodology （RSM）

关键词： Plunging airfoil propulsive efficiency Optimization Response surface methodology (RSM)

Underlying principle of efficient propulsion in flexible plunging foils

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Acta Mechanica Sinica 2014年第6期30卷 839-845页

作者： Xiao-Jue Zhu Guo-Wei He Xing Zhang LNM Institute of MechanicsChinese Academy of Sciences

Passive flexibility was found to enhance propulsive efficiency in swimming *** this study,we numerically investigate the roles of structural resonance and hydrodynamic wake resonance in optimizing efficiency of a flexible plunging *** results indicates that（1）optimal efficiency is not necessarily achieved when the driving frequency matches the structural eigenfrequency;（2）optimal efficiency always occurs when the driving frequency matches the wake resonant frequency of the time averaged velocity ***,the underlying principle of efficient propulsion in flexible plunging foil is the hydrodynamic wake resonance,rather than the structural *** addition,we also found that whether the efficiency can be optimized at the structural resonant point depends on the strength of the leading edge vortex relative to that of the trailing edge *** result of this work provides new insights into the role of passive flexibility in flapping-based propulsion.

关键词： Flexibility propulsive efficiency Structural resonance Hydrodynamic wake resonance

Aerodynamic performance enhancement forflapping airfoils by co-flow jet

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Chinese Journal of Aeronautics 2020年第10期33卷 2535-2554页

作者： Tao WU Bifeng SONG Wenping SONG Wenqing YANG Zhonghua HAN School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Yangtze River Delta Research Institute Northwestern Polytechnical UniversityTaicang 215400China Research&Development Institute Northwestern Polytechnical University in ShenzhenShenzhen 518057China

Introducing active flow control into the design of flapping wing is an effective way to enhance its aerodynamic *** this paper,a novel active flow control technology called Co-Flow Jet(CFJ)is applied to flapping *** effect of CFJ on aerodynamic performance of flapping airfoils at low Reynolds number is numerically investigated using Unsteady Reynolds Averaged Navier-Stokes(URANS)simulation with Spalart-Allmaras(SA)turbulence *** methods are validated by a NACA6415-based CFJ airfoil case and a S809 pitching airfoil *** NACA6415 baseline airfoil and NACA6415-based CFJ airfoil with jet-off and jet-on are simulated in flapping motion,with Reynolds number 70,000 and reduced frequency *** a result,CFJ airfoils with jet-on generally have better lift and thrust characteristics than baseline airfoils and jet-off airfoil when Cμgreater than 0.04,which results from the CFJ effect of reducing flow separation by injecting high-energy fluid into boundary ***,typical kinematic and geometric parameters,including the reduced frequency and the positions of the suction and injection slot,are systematically studied to figure out their influence on aerodynamic performance of the CFJ *** a variable Cμjet control strategy is proposed to further improve effective propulsive *** with using constant Cμ,an increase of effective propulsive efficiency by22.6%has been achieved by using prescribed variable CμNACA6415-based CFJ airfoil at frequency *** study may provide some guidance to performance enhancement for Flapping wing Micro Air Vehicles(FMAV).

关键词： Aerodynamic performance Co-flow jet Flapping airfoils Flow control propulsive efficiency