Characteristics of Dynamic Forces Generated by a Flapping Butterfly

2013 ◽  
Author(s):  
Taichi Kuroki ◽  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Flow Field ◽  
Vortex Ring ◽  
Elastic Deformation ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Flapping Motion ◽  
Insect Wings ◽  
Dynamic Forces ◽  
The Relationship ◽  
Significant Attention

Many studies on the mechanism of butterfly flight have been carried out. A number of recent studies have examined the flow field around insect wings. Moreover, Micro-air-vehicles and micro-flight robots that mimic the flight mechanisms of insects have attracted significant attention, and a number of MAVs and micro-flight robots that use various devices have been reported. However, these robots were not practical. One of the reasons for this is that the flying mechanism of insects has not yet been clarified sufficiently. The present authors developed a flapping-wing robot without tail wings and focused on the flow field around the wings created by the flapping motion and its elastic deformation. In the present study, we attempt to clarify the relationship between the vortex ring over the wing and the dynamic lift generated by the flapping wing. The dynamic lift becomes large rapidly in the downward flapping and reaches a maximum at a flapping angle of −30 deg. After the maximum, the dynamic lift decreases gradually and the dynamic lift in upward flapping is approximately constant. The growth of the vortex ring formed by the flapping wing was clarified to contribute significantly to the dynamic lift acting on the butterfly. We should consider the interaction of both vortex ring both in downward flapping and in upward flapping in order to estimate the dynamic lift exactly using the circulation of the vortex ring.

Characteristics of Dynamic Forces Generated by a Flapping Butterfly and its Wake Structure

2017 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Butterfly Wing ◽  
Vortex Loop ◽  
Insect Wing ◽  
Fluid Forces ◽  
Insect Wings ◽  
Piv Measurement ◽  
Dynamic Forces ◽  
Butterfly Wings ◽  
The Relationship

A typical example of the flow field around a moving elastic body is that around butterfly wings. Butterflies fly by skillfully controlling this flow field, and vortices are generated around their bodies. The motion of their elastic wings produces dynamic fluid forces by manipulating the flow field. For this reason, there has been increased academic interest in the flow field and dynamic fluid forces produced by butterfly wings. A number of recent studies have qualitatively and quantitatively examined the flow field around insect wings. In some such previous studies, the vortex ring or vortex loop formed on the wing was visualized. However, the characteristics of dynamic forces generated by the flapping insect wing are not yet sufficiently understood. The purpose of the present study is to investigate the characteristics of dynamic lift and thrust produced by the flapping butterfly wing and the relationship between the dynamic lift and thrust and the flow field around the butterfly. We conducted the dynamic lift and thrust measurements of a fixed flapping butterfly, Idea leuconoe, using a six-axes sensor. Moreover, two-dimensional PIV measurement was conducted in the wake of the butterfly. The butterfly produced dynamic lift in downward flapping which became maximum at a flapping angle of approximately 0.0 deg. At the same time, the butterfly produced negative dynamic thrust during downward flapping. The negative dynamic thrust was not produced hydrodynamically by a flapping butterfly wing because a jet was not formed in front of the butterfly. The negative dynamic thrust was the kicking force for jumping and the maximum of this kicking force was about 6.0 times as large as the weight. On the other hand, the butterfly produced dynamic thrust in upward flapping which was approximately 6.0 times as large as the weight of the butterfly. However, the attacking force by the abdomen of the butterfly was included in the dynamic thrust and we have not yet clarified quantitatively the dynamic thrust produced by the butterfly wing.

The Growth of Vortices in the Vicinity of a Wall of Elastic Moving Airfoils

2013 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Tomoki Kurinami ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Elastic Body ◽  
Elastic Deformation ◽  
Growth Process ◽  
Experimental Studies ◽  
Strain Component ◽  
Pitching Airfoil ◽  
The Impact ◽  
The Relationship ◽  
Significant Attention

There have been a number of studies on the flow field around a pitching airfoil and a heaving airfoil. Especially, the relationship between the wake structure and the characteristics of dynamic thrust has been clarified. Recently, the flow field around an elastic body has been attracted significant attention and the flow field is treated as a coupled problem between the fluid and structure. The flow field around an elastic body has been investigated primarily by numerical means, and there have been experimental studies. However, the details of the impact of elastic deformation effects on the growth process of vortices generated in the vicinity of the wall have not been clarified. In this study, we investigate the growth process of vortices generated in the vicinity of the wall of elastic moving airfoils experimentally. The elastic NACA0010 generates vortices in a large region of a wall and rolls up vortices, with the vortices growing gradually toward the trailing edge as a result of elastic deformation. The elastic NACA0010 has a characteristic whereby vortices having a rotational component that is stronger than the shear-strain component due to the vorticities in the vicinity of a wall of the elastic NACA0010 change not only spatial change of x- and y-components.

Dynamic Forces Acting on Elastic Heaving Airfoils Based on the Bending Stiffness Considerations

2014 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Tetsushi Nagata ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Elastic Deformation ◽  
Vortex Flow ◽  
Moving Boundary ◽  
Bending Stiffness ◽  
Fluid Forces ◽  
Dynamic Forces ◽  
Flow Phenomena ◽  
The Impact ◽  
The Relationship

In recent years the flow field in the vicinity of moving airfoils capable of flexible elastic deformation has become a focus of attention, and its effects are beginning to be understood. Flow in the vicinity of an elastically deforming airfoil may be understood as a fluid-structure interaction (FSI) problem, and the motion and deformation of elastic airfoils, as well as the associated vortex flow phenomena in their vicinity, are complicated. Especially, the shape and hardness of the elastic regions of an airfoil may affect its rigidity and its bending characteristics and for this reason the influence of such airfoils on the flow fields around them require more detailed consideration. In this study, we fix the bending stiffness, which uniquely determines the nature of the elastic deformation of an elastic airfoil, and study the impact of changes in this quantity on the flow field, as well as the parameters that govern the fluid forces acting on the airfoil. In particular, our goal is to clarify the relationship between three key parameters, Strouhal number St, Reynolds number Re and bending stiffness K and is to elucidate the nature of the dynamic forces acting on an elastic airfoil as a function of these three dimensionless parameters. The bending stiffness K of the elastic airfoil is an important parameter that determines the bending characteristics and the moving boundary conditions at the wall surfaces in the fluid. By defining the new quantity St2/K, we showed that the characteristic of dynamic forces depends on the ratio St2/K.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2008 ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

Design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely lightweight designs that accomplish these motions of the wing, using just a single, or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

Detailed Wake Structure Around Moving Elastic Airfoils and Their Characteristics of Dynamic Thrust

2012 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Tomoki Kurinami ◽  
Kazuhiro Tanaka ◽  
Takahide Tabata
Keyword(s):  
Flow Field ◽  
Vortex Flow ◽  
Micro Air Vehicles ◽  
Unsteady Motion ◽  
Flow Structures ◽  
Coupled Problem ◽  
Vortex Streets ◽  
Significant Attention ◽  
Maximum Thrust ◽  
Phase Differences

The unsteady flow field around a moving airfoil has attracted significant attention in bio-hydrodynamics, micro-air-vehicles and micro flight robots. Recently, a number of studies have been performed on the flow field around airfoils with unsteady motion in low Reynolds number regions using both experiment and numerical analysis. On the other hand, it is well known that insects and aquatic animals fly or swim by skillfully controlling their wings or fins, which deform elastically, and vortices are generated around their bodies. The flow around an elastic body is treated as a coupled problem between the fluid and structure. There have been only a few reports on the experimental evaluation of vortex flow structures around an elastic moving airfoil and their fluid dynamical properties. In this study, we investigate the wake structures behind the moving elastic airfoils and the characteristics of the dynamic thrusts acting on them. The thrust producing vortex streets are clearly formed behind the combination airfoils for all phase differences. The dynamic thrust acting on the moving elastic airfoil depends strongly on the Strouhal number based on the maximum trailing edge deformation and is independent of the moving motion and phase difference. The maximum thrust efficiency of the combination airfoil is higher than that for the pure pitching and heaving airfoils and become about 0.5 at φ = 90 deg. around St = 0.3.

scholarly journals Towards Improved Hybrid Actuation Mechanisms for Flapping Wing Micro Air Vehicles: Analytical and Experimental Investigations

Drones ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 73 ◽  
Author(s):  
Mostafa Hassanalian ◽  
Abdessattar Abdelkefi
Keyword(s):  
Kinetic Parameters ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Experimental Investigations ◽  
Flapping Motion ◽  
Efficient Mechanism ◽  
Actuation Mechanism ◽  
New Strategy ◽  
Hybrid Actuation ◽  
Air Vehicles

A new strategy is proposed in order to effectively design the components of actuation mechanisms for flapping wing micro air vehicles. To this end, the merits and drawbacks of some existing types of conventional flapping actuation mechanisms are first discussed qualitatively. Second, the relationships between the design of flapping wing actuation mechanism and the entrance requirements including the upstroke and downstroke angles and flapping frequency are determined. The effects of the components of the actuation mechanism on the kinematic and kinetic parameters are investigated. It is shown that there are optimum values for different parameters in order to design an efficient mechanism. Considering the optimized features for an actuation mechanism, the design, analysis, and fabrication of a new hybrid actuation mechanism for FWMAV named “Thunder I” with fourteen components consisting of two six-bar mechanisms are performed. The results show that this designed hybrid actuation mechanism has high symmetrical flapping motion with hinged connections for all components. The proposed methodology for the modeling and fabrication of Thunder I’s actuation mechanism can be utilized as guidelines to design efficient FWMAVs actuation mechanisms.

Modelling and Simulation of a Flapping Wing Mechanism Driven by a Brushless Servo Motor

2010 ◽  
Author(s):  
Jin Xie ◽  
Yong Chen
Keyword(s):  
Nonlinear Dynamic System ◽  
Input Voltage ◽  
Flapping Wing ◽  
Phase Lag ◽  
Servo Motor ◽  
Flapping Motion ◽  
Runge Kutta Method ◽  
Air Vehicle ◽  
And Control ◽  
The Relationship

Flapping wing mechanism is designed to generate flapping motion for a micro air vehicle. Some issues concerning with the design and control of flapping wing mechanism are discussed in this paper. Firstly the problem of phase-lag between two wings is treated. To eliminate phase-lag, a method of modifying the design is proposed. Then, motion controlling of a flapping wing mechanism by means of changing the voltage inputted to servo motor is studied. Based on Lagrange’s formulation and Kirchhoff’s voltage law, motion equation for a servo motor coupled to flapping wing mechanism is established. Fourth-order Runge-Kutta method is employed to integrate this equation. For the purpose of finding the relationship between the flapping motion and the input voltage, a response diagram obtained from simulation of the system is utilized. A crucial voltage VC is obvious in the response diagram. If the input voltage is lower than VC, the mechanism will settle at its fixed point, only when the input voltage is higher than VC, can the mechanism work in order. Both to find all fixed points and to analyze their stability for a complex nonlinear dynamic system are difficult tasks. A numerical method to deal with these difficulties is proposed. The results of simulation also show that the flapping frequency increases with the increasing of input voltage provided that the input voltage is higher than VC.

scholarly journals Artificial insect wings of diverse morphology for flapping-wing micro air vehicles

2009 ◽  
Vol 4 (3) ◽  
pp. 036002 ◽  
Author(s):  
J K Shang ◽  
S A Combes ◽  
B M Finio ◽  
R J Wood
Keyword(s):  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Insect Wings ◽  
Air Vehicles

Modified Unsteady Vortex Lattice Method for Aerodynamics of Flapping Wing Models

2015 ◽  
Author(s):  
Anh Tuan Nguyen ◽  
Jae-Hung Han
Keyword(s):  
Vortex Lattice ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Preliminary Design ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Real Motion ◽  
Flapping Motion ◽  
The Real ◽  
Vortex Lattice Method

Motivated by extensive possible applications of flapping-wing micro-air vehicles (MAVs) to various different areas, there has been an increasing amount of research related to this issue. In the stage of preliminary studies, one of the most important tasks is to predict the aerodynamic forces generated by the flapping motion. Studying aerodynamics of insects is an efficient way to approach the preliminary design of flapping-wing MAVs. In this paper, a modified version of an Unsteady Vortex Lattice Method (UVLM) is developed to compute aerodynamic forces appearing in flapping-wing models. A hawkmoth-like wing with kinematics based on the real motion is used for the simulations in this paper.

Dynamic Behaviors of Vortex Ring Rolled Up by a Butterfly Wing and its Dynamic Lift

2016 ◽  
Author(s):  
Masaki Fuchiwaki ◽  
Kazuhiro Tanaka
Keyword(s):  
Flow Field ◽  
Vortex Ring ◽  
Force Measurement ◽  
Three Dimensional ◽  
Vortex Structures ◽  
Dynamic Force ◽  
Butterfly Wing ◽  
Dynamic Behaviors ◽  
Insect Wings ◽  
Piv Measurement

The wing motion of a flying insect such as a butterfly produces fluid force by manipulating the flow field around the wing. These forces enable a butterfly to rapidly accelerate, turn, and hover. A number of recent studies have examined the flow field around insect wings. In recent years, quantitative flow visualization techniques, such as PIV measurement, have been advanced rapidly, and the study of the flow field around insect wings using PIV has been actively performed. As a result, the two- and three-dimensional vortex structures and their dynamic behaviors have been investigated quantitatively. However, the dynamic behaviors of these vortex structures have not been related to the dynamic force characteristics. The purpose of the present study is to clarify the relationship between the dynamic lift generated by the flapping butterfly wing and the dynamic behavior of the vortex ring rolled up from the butterfly wing as well as to investigate the role of the vortex ring. We conducted a dynamic force measurement of a flapping Cynthia cardui using a six-axes sensor and three kinds of shafts: a straight shaft, a short L-shaped shaft, and a long L-shaped shaft. Moreover, a two-dimensional PIV measurement was conducted in the wake of the butterfly. The butterfly is given not only negative dynamic lift but also the reactive force (positive lift) due to the jet flow induced by the vortex ring in the upward flapping. As a result, the butterfly produces dynamic lift in the downward flapping and produces not only negative dynamic lift but also dynamic lift in the upward flapping. Based on these results, it is considered that the vortex ring released into the wake contributes to the dynamic lift generated furing flight. That is, it was concluded that the vortex ring rolled up from the flapping wing has an important role in flight even after being released into the wake.

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