Flapping Wing Research Articles

A Novel Unsteady Vortex Ring Method for Aerodynamic Calculations of a Flapping Wing Rotor

A Novel Unsteady Vortex Ring Method for Aerodynamic Calculations of a Flapping Wing Rotor

Evolution of Vortex Structures Generated by a Rigid Flapping Wing with a Winglet in Quiescent Water

This study aims to the utilization of vortex structures generated through wing flapping for achieving sustainable flight, and the motivation is elicited by the phenomenon observed in natural flyers. The vortex structures in the flow field generated by a flapping rigid wing are captured using vorticity and the LAMDA2 criterion. The study investigates a comparative analysis between a wing both with and without a winglet. Moreover, the influence of flapping frequency is examined as well. For the experiments, particle image velocimetry (PIV) measurements are employed for the flow field around mechanical flapping motion in a quiescent water condition. The flapping mechanism has one-degree freedom, showing a 1:3 ratio in motion, and tested wings at 1.5 and 2.0 Hz. A “modified” vortex filamentation and fragmentation phenomenon is proposed as a significant finding in the present study, based on a comprehensive analysis of the flow field around the wing with a winglet.

Experimental and numerical study of different wing number and flapping-rotation decomposition of a flapping wing rotor unmanned aerial vehicle

The flapping wing rotor (FWR) is a novel aerial vehicle that combines the aerodynamic benefits of both a flapping wing and a rotary wing. By utilizing the passive rotation effect resulting from the flexible deformation of the center symmetric flapping wing, the FWR can enhance its lift force. However, previous research has neglected to explore the mechanism behind the flapping-rotation motion of a flyable FWR, which elucidates its lift advantage compared to conventional flapping motion. Additionally, the impact of varying wing number on the flapping-rotation motion and performance of the FWR has not been taken into consideration. Therefore, it is imperative to conduct an experimental analysis to ascertain the impact of flapping-rotation decomposition and varying wing quantities on FWR. In this study, our prior vehicle design, which exhibited consistent stable hovering and maneuvering capabilities, is employed to construct the flapping wing rotor experiment system. Through this unique experimental system, the effects of flapping-rotation decomposition and different wing quantities on FWR are individually investigated. Additionally, computational fluid dynamics simulation is utilized as an auxiliary and supplementary approach to analyze the aerodynamic characteristics of the flapping-rotation motion. The result proves that the stable flapping-rotation motion does produce a more significant lift increase than the normal flapping motions. Under the premise of stable flapping-rotation motion, more wings will not only produce more lift but also require more driving power. The interactions between the wings also affect the flapping-rotation motion.

Ceiling effect of flapping wing rotorcrafts to enable energy-efficient perching

Flapping wing rotorcrafts (FWRs) combine both the motion characteristics of flapping and rotary wings, exhibiting high aerodynamic efficiency at low Reynolds numbers. In this paper, the ceiling effect of FWRs has been studied through numerical and experimental methods to further investigate the aerodynamic performance of FWRs operating under a ceiling and to explore the feasibility of enhancing the flight efficiency of FWRs via ceiling-effect-based perching locomotion. Based on the momentum theory and blade element methods, a theoretical model is first established to predict the additional thrust generated by the FWR operating under the ceiling. Additionally, to uncover the detailed aerodynamic mechanisms of FWRs' ceiling effect, the computational fluid dynamics (CFD) simulations were conducted to analyze the changes in force production and flow field around the FWR at 75–115 mm distances from the ceiling. Furthermore, experimental methods were employed to validate the theoretical model and CFD simulation. The results demonstrate a continuous increase in the thrust from 19.18 to 22.15 gf as the ceiling distance decreases, while the total energy consumption remains relatively constant. Leveraging the ceiling effect, the tested FWR could achieve an additional lift force of up to 9.5% at 75 mm ceiling height with a 33 Hz flapping frequency. Finally, a ceiling perching demonstration was conducted to validate the feasibility of achieving FWRs' energy-efficient locomotion based on ceiling effects. Our study highlights the positive influence of ceiling effect on FWRs, showing a promising way to further improve the flight efficiency of FWRs.

Design And Analysis of Flapping Wing Aircraft Based on Crank Mechanism

This paper is proposed a flapping wing aircraft based on the crank slider mechanism to solve the problems of the two flapping wing structures, such as synchronization and excessive local stress common to existing ornithopters. MATLAB is used to solve the equations to determine the dimensions of the individual components, and the 3D model is designed by SolidWorks software. The static analysis on flapping wings, the static stress, and the static strain distribution map of flapping wings are carried out. Moreover, the mechanism of flapping wing aircraft is modeled in Adams software, which simulates the actual structure by designing the kinematic constraint relationships between the components. It was concluded that the flapping wing could achieve a flapping angle of 30 degrees in one cycle, which was consistent with the simulation results by MATLAB. Furthermore, it was found that the first principal stress of the danger point was less than the yield strength of the material to determine the rationality of material selection. Finally, the fluid trace distribution on the upper and lower sides of the flapping wings was analyzed, which was consistent with the actual situation.

About the Wing and Whirl Flutter of a Slender Wing–Propeller System

Next-generation aircraft designs often incorporate multiple large propellers attached along the wingspan (distributed electric propulsion), leading to highly flexible dynamic systems that can exhibit aeroelastic instabilities. This paper introduces a validated methodology to investigate the aeroelastic instabilities of wing–propeller systems and to understand the dynamic mechanism leading to wing and whirl flutter and transition from one to the other. Factors such as nacelle positions along the wing span and chord and its propulsion system mounting stiffness are considered. Additionally, preliminary design guidelines are proposed for flutter-free wing–propeller systems applicable to novel aircraft designs. The study demonstrates how the critical speed of the wing–propeller systems is influenced by the mounting stiffness and propeller position. Weak mounting stiffnesses result in whirl flutter, while hard mounting stiffnesses lead to wing flutter. For the latter, the position of the propeller along the wing span may change the wing mode shapes and thus the flutter mechanism. Propeller positions closer to the wing tip enhance stability, but pusher configurations are more critical due to the mass distribution behind the elastic axis.

Flutter investigation and deep learning prediction of FG composite wing reinforced with carbon nanotube

Abstract The flutter of a composite wing reinforced with functionally graded carbon nanotubes (CNTs) has been investigated. A rectangular plate models a supersonic wing with cantilever boundary conditions. To determine displacement fields of a moderately thick plate, shear deformation theory is used. Using the Hamilton principle, a first-order piston theory was used to simulate supersonic airflow. This study examines four types of CNT thickness. Also, four different CNT distribution patterns are investigated. In a two-layer asymmetric composite, the effects of patch mass, mass distribution, fiber orientation angle, and distribution of CNTs were examined. Moreover, the results are compared and verified with other studies. A greater mass ratio led to a smaller flutter boundary, while a longer added mass increased the flutter boundary. A variation in the distribution pattern in CNT fiber orientation results in a distinct behavior of the flutter boundary for asymmetric composites with increasing orientation angles. The artificial neural network is utilized to predict the damping ratio, and the results showed great accuracy compared to the study results. Hyperparameter tuning is employed for better optimizing the predictive models.

A hybrid energy harvester inspired by bionic flapping wing structure based on magnetic levitation.

A hybrid energy harvester based on magnetic levitation is inspired by the structure of the flapping wing, which consists of two parts: one is a flapping wing structure mounted with a piezoelectric sheet, which can achieve piezoelectric energy harvesting; the other is an intermediate muscle unit, which is vertically arranged by three groups of permanent magnets to achieve magnetic levitation electromagnetic energy harvesting. An electromechanical-electromagnetic coupling model of this harvester is established based on electromechanical coupling characteristics. The simulation analysis can evaluate the magnetic field distribution and nonlinear magnetic properties and also analyze its effects on the output performance. Several experiments are designed to verify the effectiveness of the hybrid energy harvesting structure and to check the influence of the number of magnets on the output power. The maximum output power of the proposed structure can generate 13.61 mW at 4.5Hz excitation.

Design and Integration of a Flapping Wing Apparatus

Abstract In this paper, we presented the design, integration, and experimental verification of a flapping wing apparatus. The purpose for this apparatus is to provide a framework to study the applicability of various types of sensors on flapping wings in the presence of forward speed. This work is inspired by the discoveries of mechanosensory hairs on insect wings that perform like strain-gauge sensors. To design the apparatus, we started by kinematic analysis of a crank-slider mechanism to actuate the wings. After that, we constructed the equations of motion of the entire system to find the proper gear ratio, motor properties, and other geometric dimensions. For the aerodynamic modeling, we used a quasi-steady formulation and presented a closed-form solution for the aerodynamic torque. Then, we explained the integration process and manufacturing of the main parts and presented two prototypes for the apparatus. At the end, we showed the final constructed versions of the apparatus and presented the experimental response and compared them with the simulation.

Influence of Area Distribution Along the Span Direction on Flapping Wing Aerodynamics in Hover Based on Numerical Modeling Analysis

Influence of Area Distribution Along the Span Direction on Flapping Wing Aerodynamics in Hover Based on Numerical Modeling Analysis

Analysis of Aerodynamics Load of a Flapping Wing by Vortex Lattice Method

The aim of this study is to investigate the effect of changing the angle of attack and flapping angle on the aerodynamic characteristics of an unsymmetrical wing with the NACA 2412 profile. This work uses the Vortex Lattice Method. The results of this study show that increasing the flapping angle causes the pitching moment to decrease while induced drag and moment coefficient increase, meanwhile, the lift coefficient increases at positive angles of attack and then decreases at negative angles of attack. The pitching moment decreases with increasing angle of attack at positive flap angles, but this value increases at negative flap angles. Meanwhile, the induced drag decreases from an angle of attack -15° to a minimum at an angle of attack -5° and then increases. The moment coefficient increases with increasing angle of attack at positive flapping angles, but decreases at negative flapping angles. Meanwhile, the lift coefficient increases with increasing angle of attack.

Gliding Analysis of Segmented Flapping Wing

A variety of aircraft morphing technologies have been investigated and represented by various researchers in the public domain. The morphing wing concepts involved the modification of aircraft wings during the in-flight course. Most of the technologies/concepts were based on biomimicry, where wing aerodynamic performance improved due to the change in wing shape. Here we describe a novel concept where in the flow parameters of airfoils arranged in configurations are investigated. The flow parameters are investigated using the numerical simulation tool ANSYS. A 2d flow simulation is performed using a Fluent solver to evaluate the flow configuration of the airfoils arranged in different configurations. The first configuration of airfoils is named a base, wherein the airfoils are arranged at zero angles of attack. The other two configurations are arranged by increasing the angular position of airfoils i.e., 15, 30, and 45 degrees. All these configurations are aerodynamically investigated at different sub-sonic speeds.

Bio-inspired Flapping Wing Aerodynamics: A Review

Bio-inspired Flapping Wing Aerodynamics: A Review

NUMERICAL SIMULATION OF 3D DARCY-FORCHHEIMER HYBRID NANOFLUID FLOW WITH HEAT SOURCE/SINK AND PARTIAL SLIP EFFECT ACROSS A SPINNING DISC

The current study explains the numerical simulation for the Darcy-Forchheimer (DF) hybrid nanofluid (HNF) flow across a permeable rotating disc. The HNF is prepared with the addition of AA7072 and AA7075 (aluminum alloys) nanoparticles (NPs) in water. Aluminum alloys are frequently used in aircraft parts like fuselages and wing flaps due to their lightweight and durability. Additionally, making M16 rifles for the American military is another intriguing application of aluminum alloys. The fluid flow has been estimated with the significances of thermal radiation, DF effect, viscous dissipation, thermal slip condition, and exponential heat source/sink. The modeled equations are simplified to an ordinary system of differential equations (ODEs) by substituting similarity variables. The obtained set of equations is solved using the parametric continuation method (PCM). It has been noticed that with the HNF, both the radial and axial velocity diminishes with the upshot of the porosity parameter and DF term. The velocity and temperature fields reduce with the rising numbers of aluminum alloys (AA7072 and AA7075).

The Impact of the Butterfly Effect Concept on Jorie Graham's Selected Poems

The butterfly effect states that the flapping of a butterfly's wings in Brazil causes a hurricane in Texas. It is the main concept of chaos theory that is developed by the American meteorologist Edward Lorenz. Besides, it is a term used to explain the high sensitivity of nonlinear dynamical systems to their initial conditions. The study applies the concept of the butterfly effect to the poems of the American poet Jorie Graham. It analyses two collections of her poems, Erosion and The End of Beauty, where the main purpose is to prove that every minor change in a chaotic poem, whether in the external form or in the content, leads the reader to order in one way or another. In other words, from the middle of the chaotic poem emerges a small part that restores order to the whole poem. The poet’s seemingly disordered techniques employed in her poems are strategically used to create the sense of order in the middle of chaos.

Study of Communal Behavior of Black-Winged Stilt with other Bird Species in Selected Wetlands of Kota (Rajasthan)

A comprehensive understanding of bird behaviour is essential for developing and enhancing avian life-history theory content and organizing efficient management and conservation plans. The knowledge of the crucial nesting characteristics and the tactics used by birds throughout their life histories often fluctuate between environments. Despite being seen in small groups, the black-winged stilt has an intriguing social behaviour that demonstrates flexibility. These birds are sociable and will often gather in large groups. But during the breeding season, in particular, their social dynamics shift. They break off from their usual groupings now and either form pairs or congregate in bigger groups. During this time, they display specific behavior with other bird species found in their habitat, especially with those species with which they share their feeding and nesting sites. Their various behaviors can be understood on the basis of continuous study of their vocalization, flapping of wings and body posture. In this context, the communal behavior of Black-winged Stilt has been studied at the wetlands Alniya and Abheda ponds located in Kota.

A Bibliometric Analysis of Flapping Wing Instrumentation

There are flapping wing-style systems being developed by various institutions around the world. However, despite there being many systems that superficially appear robust, there is no viable flapping wing flying system at this time. We identified a gap in knowledge and capability, which is that the lack of appropriate instrumentation seems to be a major roadblock in further developing flapping wing flying systems. There is no complete solution in regards to instrumentation and sensing at the appropriate scales. This paper seeks to critically examine and classify the existing instrumentation utilized and reported in the literature and attempts to identify the path forward for flapping wing-style instrumentation.

Time-history performance optimization of flapping wing motion using a deep learning based prediction model

Flapping Wing Micro Aerial Vehicles (FWMAVs) have caused great concern in various fields because of their high efficiency and maneuverability. Flapping wing motion is a very important factor that affects the performance of the aircraft, and previous works have always focused on the time-averaged performance optimization. However, the time-history performance is equally important in the design of motion mechanism and flight control system. In this paper, a time-history performance optimization framework based on deep learning and multi-island genetic algorithm is presented, which is designed in order to obtain the optimal two-dimensional flapping wing motion. Firstly, the training dataset for deep learning neural network is constructed based on a validated computational fluid dynamics method. The aerodynamic surrogate model for flapping wing is obtained after the convergence of training. The surrogate model is tested and proved to be able to accurately and quickly predict the time-history curves of lift, thrust and moment. Secondly, the optimization framework is used to optimize the flapping wing motion in two specific cases, in which the optimized propulsive efficiencies have been improved by over 40% compared with the baselines. Thirdly, a dimensionless parameter Cvariation is proposed to describe the variation of the time-history characteristics, and it is found that Cvariation of lift varies significantly even under close time-averaged performances. Considering the importance of time-history performance in practical applications, the optimization that integrates the propulsion efficiency as well as Cvariation is carried out. The final optimal flapping wing motion balances good time-averaged and time-history performance.

Numerical and experimental studies of a morphing airfoil with trailing edge high-frequency flapping

The aerodynamic performance of a morphing airfoil is numerically and experimentally investigated. The morphing airfoil is designed based on macro fiber composites, capable of trailing edge flapping during 10–90 Hz with a maximum amplitude of 0.55 mm. A numerical model with flexible deformation walls based on the experiment is established to precisely restore the actual dynamic morphing instead of segmental deformation to explore the transient aerodynamic performance of high-frequency flapping. The drag coefficient is reduced by 2.07% at the flapping frequency (ff) of 37.5 Hz compared with the rigid airfoil, while the drag coefficient and the lift coefficient increase by 4.8% and 5.8% for ff at 600 Hz. The vortex is broken up by flapping, and the corresponding position has been forwarded to the tail. Dynamic mode decomposition shows that the wing's flapping dominates the second mode and the high-frequency vortex has changed to low-frequency. The energy of higher modes is transferred to lower-order modes that the first mode's power has risen sharply from 49.29% of the rigid airfoil to 91.83%. In the wind tunnel experiment, the lift and drag forces are increased by 1.88% and 0.77% at the flapping frequency of 40 Hz, respectively. Furthermore, the lift force frequency is locked by flapping and changes from 124.9 Hz of the rigid airfoil to the flapping frequency, consistent with the computational fluid dynamics results. The research has provided a solution to reduce the drag force and increase the lift force of the aircraft by the trailing edge flapping.

Analysis of the impact of trailing-edge wing flaps on the aerodynamic characteristics and performance of the Tecnam P-2008JC aircraft

The aim of the article was to analyse the impact of three selected types of trailing-edge flaps on the aerodynamic characteristics and performance of the Tecnam P-2008JC aircraft. The SOLIDWORKS software, together with the Flow Simulation module, was used to design the 3D model of the aircraft and to simulate the air flow. The article contains descriptions of issues related to the aerodynamics and dynamics of aircraft motion, calculations describing the procedure for designing and building a model of the tested aircraft in the SOLIDWORKS software, performing simulations using the Flow Simulation module and determining the aerodynamic characteristics of the aircraft with the flaps applied, determining the basic performance of the aircraft with extended flaps, and then comparing the determined performance with the in a configuration without flaps.