In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and...In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.展开更多
Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by...Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.展开更多
This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-dis...This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials,and the deformed wing surface is modeled by a spline surface according to the rib's morphing in the chordwise direction.The Computational Fluid Dynamics(CFD)method is adopted to obtain flow-field results and aerodynamic forces.The SST-γmodel is introduced and the overset mesh technique is adopted.The numerical results show that the spanwisedistributed trailing-edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic stall.Especially when the phase difference between the trailing-edge motion and the wing pitch is-π/2,the interaction between the three-dimensional(3-D)Leading-Edge Vortex(LEV)and Trailing-Edge Vortex(TEV)is strengthened,and the work done by the aerodynamic force turns negative.This indicates that the trailing-edge deformation has the potential to suppress the oscillation amplitude of stall flutter.We also found that as the trailing-edge camber morphing varies more complexly along the spanwise direction,the suppression effect decreases accordingly.展开更多
This paper aims to design a morphing wing with both Flexible Leading Edge(FLE)and Flexible Trailing Edge(FTE)by using cellular structures,which can help the wing boost the deformation to a greater extent on the premis...This paper aims to design a morphing wing with both Flexible Leading Edge(FLE)and Flexible Trailing Edge(FTE)by using cellular structures,which can help the wing boost the deformation to a greater extent on the premise that the weight is not changed,so as to play a greater role in aerodynamic control such as gust interference.First,as for structural design,based on NACA0012,a morphing wing model constructed by 3 forms of cell structures is proposed.Then,the aerodynamic characteristics under the interference of FLE and FTE are calculated by the Computational Fluid Dynamic(CFD)method.After the surrogate model is established to predict the lift coefficient of the wing effectively,the sensitivity analysis reveals that the main sensitivity index of FTE deflection angle β is 0.565,which has the greatest influence on the lift coefficient.And the total sensitivity index of FLE deflection angle γ is increased by 78.9%,which reveals a strong coupling relationship between FLE and FTE.Finally,using Finite Element Analysis(FEA)method and experiment,the deformation capability of the model under certain static loads are obtained.The results reveal that the maximum deflection angle of the morphing wing model can be±22°at FLE and±64°at FTE,indicating strong structural stiffness and resistance to bending breakage of the model.The presented results can be useful in the design of the cellular morphing wing with multiple flexible systems.展开更多
To investigate the control of morphing wings by means of interacting effectors,this article proposes a distributed coordinated control scheme with sampled communication on the basis of a simple morphing wing model,est...To investigate the control of morphing wings by means of interacting effectors,this article proposes a distributed coordinated control scheme with sampled communication on the basis of a simple morphing wing model,established with arrayed agents. The control scheme can change the shape of airfoil into an expected one and keep it smooth during morphing. As the interconnection of communication network and the agents would make the behavior of the morphing wing system complicated,a diagrammatic stability analysis method is put forward to ensure the system stability. Two simulations are carried out on the morphing wing system by using MATLAB. The results stand witness to the feasibility of the distributed coordinated control scheme and the effectiveness of the diagrammatic stability analysis method.展开更多
Wing flapping and morphing can be very beneficial to managing the weight of micro air vehicles through coupling the aerodynamic forces with stability and control. In this letter, harvesting energy from the wing morphi...Wing flapping and morphing can be very beneficial to managing the weight of micro air vehicles through coupling the aerodynamic forces with stability and control. In this letter, harvesting energy from the wing morphing is studied to power cameras, sensors, or communication devices of micro air vehicles and to aid in the management of their power. The aerodynamic loads on flapping wings are simulated using a three-dimensional unsteady vortex lattice method. Active wing shape morphing is considered to enhance the performance of the flapping motion. A gradient-based optimization algorithm is used to pinpoint the optimal kinematics maximizing the propellent efficiency. To benefit from the wing deformation, we place piezoelectric layers near the wing roots. Gauss law is used to estimate the electrical harvested power. We demonstrate that enough power can be generated to operate a camera. Numerical analysis shows the feasibility of exploiting wing morphing to harvest energy and improving the design and performance of micro air vehicles.展开更多
Raptors are getting more attention from researchers because of their excellent flight abilities.And the excellent wing morphing ability is critical for raptors to achieve high maneuvering flight,which can be a good bi...Raptors are getting more attention from researchers because of their excellent flight abilities.And the excellent wing morphing ability is critical for raptors to achieve high maneuvering flight,which can be a good bionic inspiration for unmanned aerial vehicles(UAV)design.However,morphing wing motions of Falco peregrinus with multi postures cannot be consulted since such a motion database was nonexistent.This study aimed to provide data reference for future research in wing morphing kinetics.We used the computed tomography(CT)approach to obtain nine critical postures of the Falco peregrinus wing skeleton,followed with motion analysis of each joint and bone.Based on the obtained motion database,a six-bar kinematic model was proposed to regenerate wing motions with a high fidelity.展开更多
Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and to...Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and topology optimization design for morphing wing driven by shape memory alloys(SMAs). By simultaneously optimizing the layout of smart actuators and topology of wing substrate, the ultimately determined configuration can achieve smooth, continuous and accurate geometric shape changes. In addition, aerodynamic analysis is carried out to compare smart morphing wing with traditional hinged airfoil. Finally, the optimized smart wing structure is constructed and tested to demonstrate and verify the morphing functionality. Application setbacks are also pointed out for further investigation.展开更多
In the present paper, an ‘in-house＇ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircr...In the present paper, an ‘in-house＇ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the wing tip demonstrator for the actuators control to change the upper surface shape of the wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the wing-tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house＇ genetic algorithm was an appropriate tool in improving various aspects of a wing＇s aerodynamic performances.展开更多
The morphing wing has a significant positive effect on the aerodynamic performance of the aircraft.This paper describes a leading-edge of variable camber wing with concentrated flexibility based on the geared five-bar...The morphing wing has a significant positive effect on the aerodynamic performance of the aircraft.This paper describes a leading-edge of variable camber wing with concentrated flexibility based on the geared five-bar mechanism.The driving points of morphing skin formed by the glass fibre composite sheet were optimized to make the skin deformation smooth.A geared fivebar kinematic mechanism rigidly connected to the skin was proposed to drive the leading-edge deformation.Besides,a new kind of concentrated flexure hinge was designed using the pseudorigid-body method and applied to the joint between the rigid mechanism and the skin.Finally,the leading-edge prototypes with traditional hinges and flexure hinges were produced,respectively.The feasibility of the concentrated flexibility leading-edge was verified through the comparative experiments of ground deformation.Simultaneously,aerodynamic analysis was carried out to compare the concentrated flexure leading-edge wing with the original airfoil.展开更多
In this paper, an ‘in-house＇ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The algorithm＇s ...In this paper, an ‘in-house＇ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The algorithm＇s performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods,namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing wing-tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.展开更多
In aircraft wing design,engineers aim to provide the best possible aerodynamic performance under cruise flight conditions in terms of lift-to-drag ratio.Conventional control surfaces such as flaps,ailerons,variable wi...In aircraft wing design,engineers aim to provide the best possible aerodynamic performance under cruise flight conditions in terms of lift-to-drag ratio.Conventional control surfaces such as flaps,ailerons,variable wing sweep and spoilers are used to trim the aircraft for other flight conditions.The appearance of the morphing wing concept launched a new challenge in the area of overall wing and aircraft performance improvement during different flight segments by locally altering the flow over the aircraft＇s wings.This paper describes the development and application of a control system for an actuation mechanism integrated in a new morphing wing structure.The controlled actuation system includes four similar miniature electromechanical actuators disposed in two parallel actuation lines.The experimental model of the morphing wing is based on a full-scale portion of an aircraft wing,which is equipped with an aileron.The upper surface of the wing is a flexible one,being closed to the wing tip;the flexible skin is made of light composite materials.The four actuators are controlled in unison to change the flexible upper surface to improve the flow quality on the upper surface by delaying or advancing the transition point from laminar to turbulent regime.The actuators transform the torque into vertical forces.Their bases are fixed on the wing ribs and their top link arms are attached to supporting plates fixed onto the flexible skin with screws.The actuators push or pull the flexible skin using the necessary torque until the desired vertical displacement of each actuator is achieved.The four vertical displacements of the actuators,correlated with the new shape of the wing,are provided by a database obtained through a preliminary aerodynamic optimization for specific flight conditions.The control system is designed to control the positions of the actuators in real time in order to obtain and to maintain the desired shape of the wing for a specified flight condition.The feasibility and effectiveness of the developed control system by use of a proportional fuzzy feed-forward methodology are demonstrated experimentally through bench and wind tunnel tests of the morphing wing model.展开更多
Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compac...Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compact mesostructures,excellent energy absorption properties and considerable weight to strength ratios.Herein,a honeycomb-inspired triboelectric nanogenerator(h-TENG)is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure.The wavy surface comprises a multilayered thin film structure(combining polyethylene terephthalate,silver nanowires and fluorinated ethylene propylene)fabricated through high-temperature thermoplastic molding and wafer-level bonding process.With superior synchronization of large amounts of energy generation units with honeycomb cells,the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage,short-circuit current and output power of 1207 V,68.5μA and 12.4 mW,respectively,corresponding to a remarkable peak power density of 0.275 mW cm^(−3)(or 2.48 mW g^(−1))under hand pressing excitations.Attributed to the excellent elastic property of self-rebounding honeycomb structure,the flexible and transparent h-TENG can be easily pressed,bent and integrated into shoes for real-time insole plantar pressure mapping.The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time.This research demonstrates this new conceptualizing single h-TENG device’s versatility and viability for broad-range real-world application scenarios.展开更多
Abstract Morphing wing structures are widely considered among the most promising technologies for the improvement of aerodynamic performances in large civil aircraft.The controlled adaptation of the wing shape to exte...Abstract Morphing wing structures are widely considered among the most promising technologies for the improvement of aerodynamic performances in large civil aircraft.The controlled adaptation of the wing shape to external operative conditions naturally enables the maximization of aircraft aerodynamic efficiency,with positive fallouts on the amount of fuel burned and pollutant emissions.The benefits brought by morphing wings at aircraft level are accompanied by the criticalities of the enabling technologies,mainly involving weight penalties,overconsumption of electrical power,and safety issues.The attempt to solve such criticalities passes through the development of novel design approaches,ensuring the consolidation of reliable structural solutions that are adequately mature for certification and in-flight operations.In this work,the development phases of a multimodal camber morphing wing flap,tailored for large civil aircraft applications,are outlined with specific reference to the activities addressed by the author in the framework of the Clean Sky program.The flap is morphed according to target shapes depending on aircraft flight conditions and defined to enhance high-lift performances during takeoff and landing,as well as wing aerodynamic efficiency during cruise.An innovative system based on finger-like robotic ribs driven by electromechanical actuators is proposed as morphing-enabling technology;the maturation process of the device is then traced from the proof of concept to the consolidation of a true-scale demonstrator for pre-flight ground validation tests.A step-by-step approach involving the design and testing of intermediate demonstrators is then carried out to show the compliance of the adaptive system with industrial standards and safety requirements.The technical issues encountered during the development of each intermediate demonstrator are critically analyzed,and justifications are provided for all the adopted engineering solutions.Finally,the layout of the true-scale demonstrator is presented,with emphasis on the architectural strengths,enabling the forthcoming validation in real operative conditions.展开更多
The morphing wing can improve the flight performance during different phases.However,research has been subject to limitations in aerodynamic characteristics of the morphing wing with a flexible leading-edge.The comput...The morphing wing can improve the flight performance during different phases.However,research has been subject to limitations in aerodynamic characteristics of the morphing wing with a flexible leading-edge.The computational fluid dynamic method and dynamic mesh were used to simulate the continuous morphing of the flexible leading-edge.After comparing the steady aerodynamic characteristics of morphing and conventional wings,this study examined the unsteady aerodynamic characteristics of morphing wings with upward and downward deflections of the leading-edge at different frequencies.The numerical results show that for the steady aerodynamic,the leading-edge deflection mainly affects the stall characteristic.The downward deflection of the leading-edge increases the stall angle of attack and nose-down pitching moment.The results are opposite for the upward deflection.For the unsteady aerodynamic,at a small angle of attack,the transient lift coefficient of the upward deflection,growing with the increase of deflection frequency,is larger than that of the static case.The transient lift coefficient of the downward deflection,decreasing with the increase of deflection frequency,is smaller than that of the static case.However,at a large angle of attack,an opposite effect of deflection frequency on the transient lift coefficient was demonstrated.The transient lift coefficient is larger than that of the static case when the leading edge is in the nose-up stage,and lower than that of the static one in the nose-down stage.展开更多
Morphing technology is one of the most effective methods to improve the flight efficiency of aircraft.Traditional control surfaces based morphing method is mature and widely used on current civil and military aircraft...Morphing technology is one of the most effective methods to improve the flight efficiency of aircraft.Traditional control surfaces based morphing method is mature and widely used on current civil and military aircraft,but insufficiently effective for the entire flight envelope.Recent research on morphing wing still faces the challenge that the skin material for morphing should be both deformable and stiff.In this study,a continuous morphing trailing-edge wing with a new multi-stable nano skin material fabricated using surface mechanical attrition treatment technology was proposed and designed.Computational fluid dynamics simulation was used to study the aerodynamic performance of the continuous morphing trailing-edge wing.Results show that the lift coefficient increases with the increase of deflection angle and so does the lift-drag ratio at a small angle of attack.More importantly,compared with the wing using flaps,the continuous morphing trailing-edge wing can reduce drag during the morphing process and its overall aerodynamic performance is improved at a large angle of attack range.Flow field analysis reveals that the continuous morphing method can delay flow separation in some situations.展开更多
A novel 0-Poisson＇s ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method （FEM） and experiments have been...A novel 0-Poisson＇s ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method （FEM） and experiments have been performed to validate the theoretical model. The in-plane characteristics of the cosine honeycomb are compared with accordion honeycomb through analytical models and experiments. Finally, the application of the cosine honeycomb on a variable camber wing is studied. Studies show that mechanical model agrees well with results of FEM and experiments. The transverse non-dimensional elastic modulus of the cosine honeycomb increases （decreases） when the wavelength or the wall width increases （decreases）, or when the amplitude decreases （increases）. Compared with accordion honeycomb, the transverse non-dimensional elastic modulus of the cosine honeycomb is smaller, which means the driving force is smaller and the power consumption is less during deformation. In addition, the cosine honeycomb can satisfy the deform- ing requirements of the variable camber wing.展开更多
This article investigates gain self-scheduled H 1 robust control system design for a tailless fold- ing-wing morphing aircraft in the wing shape varying process. During the wing morphing phase, the aircraft＇s dynamic...This article investigates gain self-scheduled H 1 robust control system design for a tailless fold- ing-wing morphing aircraft in the wing shape varying process. During the wing morphing phase, the aircraft＇s dynamic response will be governed by time-varying aerodynamic forces and moments. Nonlinear dynamic equations of the morphing aircraft are linearized by using Jacobian linearization approach, and a linear parameter varying （LPV） model of the morphing aircraft in wing folding is obtained. A multi-loop controller for the morphing aircraft is formulated to guarantee stability for the wing shape transition process. The proposed controller uses a set of inner-loop gains to provide stability using classical techniques, whereas a gain self-scheduled H 1 outer-loop controller is devised to guarantee a specific level of robust stability and performance for the time-varying dynamics. The closed-loop simulations show that speed and altitude vary slightly during the whole wing folding process, and they converge rapidly after the process ends. This proves that the gain self-scheduled H 1 robust controller can guarantee a satisfactory dynamic performance for the morphing aircraft during the whole wing shape transition process. Finally, the flight control system＇s robustness for the wing folding process is verified according to uncertainties of the aerodynamic parameters in the nonlinear model.展开更多
The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale w...The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale wing tip for a real aircraft equipped with an aileron.The morphing actuation of the model is based on a mechanism with four similar in house designed and manufactured actuators,positioned inside the wing on two parallel lines.Each of the four actuators used a BrushLess Direct Current(BLDC)electric motor integrated with a mechanical part performing the conversion of the angular displacements into linear displacements.The following have been chosen as successive steps in the design of the actuator control system:(A)Mathematical and software modelling of the actuator;(B)Design of the control system architecture and tuning using Internal Model Control(IMC)methodology;(C)Numerical simulation of the controlled actuator and its testing on bench and wind tunnel.The morphing wing experimental model is tested both at the laboratory level,with no airflow,to evaluate the components integration and the whole system functioning,but also in the wind tunnel,in the presence of airflow,to evaluate its behavior and the aerodynamic gain.展开更多
Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and c...Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and control surfaces into a seamless wing and integrates the primary structure together with the internal control system.It makes use of the wing aeroelastic deformation induced by the control surface to gain direct force control through desirable redistribution of aerodynamic forces.However some unknown mechanical parameters of the control system and complexity of the integrated structure become a main challenge for dynamic modeling of morphing wing.To solve the problem,a method of test data based modal sensitivity analysis is presented to improve the morphing wing FE model by evaluating the unknown parameters and identifying the modeling boundary conditions.An innovative seamless morphing wing with the structure integrated with a flexible trailing edge control system is presented for the investigation.An experimental model of actuation system driven by a servo motor for the morphing wing is designed and established.By performing a vibration test and the proposed modal sensitivity analysis,the unknown torsional stiffness of the servo motor and the boundary condition of the actuation mechanism model is identified and evaluated.Comparing with the test data,the average error of the first four modal frequency of the improved FE model is reduced significantly to less than 4%.To further investigate the morphing wing modeling,a wing box and then a whole morphing wing model including the skin and integrated with the trailing edge actuation system are established and tested.By using the proposed method,the FE model is improved by relaxing the constraint between the skin and actuation mechanism.The results show that the average error of the first three modal frequency of the improved FE model is reduced to less than 6%.The research results demonstrate that the presented seamless morphing wing integrated with a flexible trailing edge control surface can improve aerodynamic characteristics.By using the test data based modal sensitivity analysis method,the unknown parameter and boundary condition of the actuation model can be determined to improve the FE model.The problem in dynamic modeling of high accuracy for a morphing wing can be solved in an effective manner.展开更多
文摘In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.
基金sponsored by Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2024037)。
文摘Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.
基金co-supported by the National Natural Science Foundation of China(No.12472332)。
文摘This paper investigates the influence of the spanwise-distributed trailing-edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re=2×10^(5).The mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials,and the deformed wing surface is modeled by a spline surface according to the rib's morphing in the chordwise direction.The Computational Fluid Dynamics(CFD)method is adopted to obtain flow-field results and aerodynamic forces.The SST-γmodel is introduced and the overset mesh technique is adopted.The numerical results show that the spanwisedistributed trailing-edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic stall.Especially when the phase difference between the trailing-edge motion and the wing pitch is-π/2,the interaction between the three-dimensional(3-D)Leading-Edge Vortex(LEV)and Trailing-Edge Vortex(TEV)is strengthened,and the work done by the aerodynamic force turns negative.This indicates that the trailing-edge deformation has the potential to suppress the oscillation amplitude of stall flutter.We also found that as the trailing-edge camber morphing varies more complexly along the spanwise direction,the suppression effect decreases accordingly.
基金co-supported by the National Natural Science Foundation of China(No.52402460)project funded by the China Postdoctoral Science Foundation(No.2024T171113)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This paper aims to design a morphing wing with both Flexible Leading Edge(FLE)and Flexible Trailing Edge(FTE)by using cellular structures,which can help the wing boost the deformation to a greater extent on the premise that the weight is not changed,so as to play a greater role in aerodynamic control such as gust interference.First,as for structural design,based on NACA0012,a morphing wing model constructed by 3 forms of cell structures is proposed.Then,the aerodynamic characteristics under the interference of FLE and FTE are calculated by the Computational Fluid Dynamic(CFD)method.After the surrogate model is established to predict the lift coefficient of the wing effectively,the sensitivity analysis reveals that the main sensitivity index of FTE deflection angle β is 0.565,which has the greatest influence on the lift coefficient.And the total sensitivity index of FLE deflection angle γ is increased by 78.9%,which reveals a strong coupling relationship between FLE and FTE.Finally,using Finite Element Analysis(FEA)method and experiment,the deformation capability of the model under certain static loads are obtained.The results reveal that the maximum deflection angle of the morphing wing model can be±22°at FLE and±64°at FTE,indicating strong structural stiffness and resistance to bending breakage of the model.The presented results can be useful in the design of the cellular morphing wing with multiple flexible systems.
基金National Natural Science Foundation of China (90605007)
文摘To investigate the control of morphing wings by means of interacting effectors,this article proposes a distributed coordinated control scheme with sampled communication on the basis of a simple morphing wing model,established with arrayed agents. The control scheme can change the shape of airfoil into an expected one and keep it smooth during morphing. As the interconnection of communication network and the agents would make the behavior of the morphing wing system complicated,a diagrammatic stability analysis method is put forward to ensure the system stability. Two simulations are carried out on the morphing wing system by using MATLAB. The results stand witness to the feasibility of the distributed coordinated control scheme and the effectiveness of the diagrammatic stability analysis method.
文摘Wing flapping and morphing can be very beneficial to managing the weight of micro air vehicles through coupling the aerodynamic forces with stability and control. In this letter, harvesting energy from the wing morphing is studied to power cameras, sensors, or communication devices of micro air vehicles and to aid in the management of their power. The aerodynamic loads on flapping wings are simulated using a three-dimensional unsteady vortex lattice method. Active wing shape morphing is considered to enhance the performance of the flapping motion. A gradient-based optimization algorithm is used to pinpoint the optimal kinematics maximizing the propellent efficiency. To benefit from the wing deformation, we place piezoelectric layers near the wing roots. Gauss law is used to estimate the electrical harvested power. We demonstrate that enough power can be generated to operate a camera. Numerical analysis shows the feasibility of exploiting wing morphing to harvest energy and improving the design and performance of micro air vehicles.
基金supported by the National Natural Science Foundation of China(Grant Nos.52175279,52075489,and 51705459)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LY20E050022 and LGG20E050017)。
文摘Raptors are getting more attention from researchers because of their excellent flight abilities.And the excellent wing morphing ability is critical for raptors to achieve high maneuvering flight,which can be a good bionic inspiration for unmanned aerial vehicles(UAV)design.However,morphing wing motions of Falco peregrinus with multi postures cannot be consulted since such a motion database was nonexistent.This study aimed to provide data reference for future research in wing morphing kinetics.We used the computed tomography(CT)approach to obtain nine critical postures of the Falco peregrinus wing skeleton,followed with motion analysis of each joint and bone.Based on the obtained motion database,a six-bar kinematic model was proposed to regenerate wing motions with a high fidelity.
基金supported by National Natural Science Foundation of China (Nos. 11802243 and 11902258)Natural Science Foundation of Shaanxi Province (No. 2019JQ-176)+1 种基金Key Project of NSFC (Nos. 51790171, 51761145111 and 51735005)NSFC for Excellent Young Scholars (No. 11722219)。
文摘Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and topology optimization design for morphing wing driven by shape memory alloys(SMAs). By simultaneously optimizing the layout of smart actuators and topology of wing substrate, the ultimately determined configuration can achieve smooth, continuous and accurate geometric shape changes. In addition, aerodynamic analysis is carried out to compare smart morphing wing with traditional hinged airfoil. Finally, the optimized smart wing structure is constructed and tested to demonstrate and verify the morphing functionality. Application setbacks are also pointed out for further investigation.
基金Bombardier Aerospace,Thales Canada,The Consortium in Research and Aerospace in Canada(CRIAQ)the Natural Sciences and Engineering Research Council of Canada(NSERC)for their financial support
文摘In the present paper, an ‘in-house＇ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the wing tip demonstrator for the actuators control to change the upper surface shape of the wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the wing-tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house＇ genetic algorithm was an appropriate tool in improving various aspects of a wing＇s aerodynamic performances.
基金supported by National Natural Science Foundation of China(No.50975230)Natural Science Basic Research Plan in Shaanxi Province of China(No.2017JM500)National Natural Science Foundation of China(No.51375383)。
文摘The morphing wing has a significant positive effect on the aerodynamic performance of the aircraft.This paper describes a leading-edge of variable camber wing with concentrated flexibility based on the geared five-bar mechanism.The driving points of morphing skin formed by the glass fibre composite sheet were optimized to make the skin deformation smooth.A geared fivebar kinematic mechanism rigidly connected to the skin was proposed to drive the leading-edge deformation.Besides,a new kind of concentrated flexure hinge was designed using the pseudorigid-body method and applied to the joint between the rigid mechanism and the skin.Finally,the leading-edge prototypes with traditional hinges and flexure hinges were produced,respectively.The feasibility of the concentrated flexibility leading-edge was verified through the comparative experiments of ground deformation.Simultaneously,aerodynamic analysis was carried out to compare the concentrated flexure leading-edge wing with the original airfoil.
基金the Consortium in Research and Aerospace in Canada (CRIAQ)the Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support
文摘In this paper, an ‘in-house＇ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The algorithm＇s performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods,namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing wing-tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.
基金the Consortium for Research and Innovation in Aerospace in Quebec(CRIAQ)the National Sciences and Engineering Research Council (NSERC) for their funding of the CRIAQ MDO 505 project
文摘In aircraft wing design,engineers aim to provide the best possible aerodynamic performance under cruise flight conditions in terms of lift-to-drag ratio.Conventional control surfaces such as flaps,ailerons,variable wing sweep and spoilers are used to trim the aircraft for other flight conditions.The appearance of the morphing wing concept launched a new challenge in the area of overall wing and aircraft performance improvement during different flight segments by locally altering the flow over the aircraft＇s wings.This paper describes the development and application of a control system for an actuation mechanism integrated in a new morphing wing structure.The controlled actuation system includes four similar miniature electromechanical actuators disposed in two parallel actuation lines.The experimental model of the morphing wing is based on a full-scale portion of an aircraft wing,which is equipped with an aileron.The upper surface of the wing is a flexible one,being closed to the wing tip;the flexible skin is made of light composite materials.The four actuators are controlled in unison to change the flexible upper surface to improve the flow quality on the upper surface by delaying or advancing the transition point from laminar to turbulent regime.The actuators transform the torque into vertical forces.Their bases are fixed on the wing ribs and their top link arms are attached to supporting plates fixed onto the flexible skin with screws.The actuators push or pull the flexible skin using the necessary torque until the desired vertical displacement of each actuator is achieved.The four vertical displacements of the actuators,correlated with the new shape of the wing,are provided by a database obtained through a preliminary aerodynamic optimization for specific flight conditions.The control system is designed to control the positions of the actuators in real time in order to obtain and to maintain the desired shape of the wing for a specified flight condition.The feasibility and effectiveness of the developed control system by use of a proportional fuzzy feed-forward methodology are demonstrated experimentally through bench and wind tunnel tests of the morphing wing model.
基金This research is supported by the National Natural Science Foundation of China Grant(Nos.51705429&61801525)the Fundamental Research Funds for the Central Universities,Guangdong Natural Science Funds Grant(2018A030313400)+1 种基金Space Science and Technology Foundation,111 Project No.B13044UK Engineering and Physical Sciences Research Council(EPSRC)for support under grant EP/P018998/1,Newton Mobility Grant(IE161019)through Royal Society.
文摘Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compact mesostructures,excellent energy absorption properties and considerable weight to strength ratios.Herein,a honeycomb-inspired triboelectric nanogenerator(h-TENG)is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure.The wavy surface comprises a multilayered thin film structure(combining polyethylene terephthalate,silver nanowires and fluorinated ethylene propylene)fabricated through high-temperature thermoplastic molding and wafer-level bonding process.With superior synchronization of large amounts of energy generation units with honeycomb cells,the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage,short-circuit current and output power of 1207 V,68.5μA and 12.4 mW,respectively,corresponding to a remarkable peak power density of 0.275 mW cm^(−3)(or 2.48 mW g^(−1))under hand pressing excitations.Attributed to the excellent elastic property of self-rebounding honeycomb structure,the flexible and transparent h-TENG can be easily pressed,bent and integrated into shoes for real-time insole plantar pressure mapping.The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time.This research demonstrates this new conceptualizing single h-TENG device’s versatility and viability for broad-range real-world application scenarios.
基金The researches described in this paper have been carried out in the framework of the Clean Sky Green Regional Aircraft ITD(Low Noise Configuration Domain)and Airgreen2 projectsThe activities have gratefully received funding respectively from the Cleans Sky and the Clean Sly 2 Joint Undertaking,under the European Union FP7 and H2020 research and innovation programs,Grant Agreements No.CSJU-GAM-GRA-2008-001 and No.807089—REG GAM 2018—H2020-IBA-CS2-GAMS-2017.
文摘Abstract Morphing wing structures are widely considered among the most promising technologies for the improvement of aerodynamic performances in large civil aircraft.The controlled adaptation of the wing shape to external operative conditions naturally enables the maximization of aircraft aerodynamic efficiency,with positive fallouts on the amount of fuel burned and pollutant emissions.The benefits brought by morphing wings at aircraft level are accompanied by the criticalities of the enabling technologies,mainly involving weight penalties,overconsumption of electrical power,and safety issues.The attempt to solve such criticalities passes through the development of novel design approaches,ensuring the consolidation of reliable structural solutions that are adequately mature for certification and in-flight operations.In this work,the development phases of a multimodal camber morphing wing flap,tailored for large civil aircraft applications,are outlined with specific reference to the activities addressed by the author in the framework of the Clean Sky program.The flap is morphed according to target shapes depending on aircraft flight conditions and defined to enhance high-lift performances during takeoff and landing,as well as wing aerodynamic efficiency during cruise.An innovative system based on finger-like robotic ribs driven by electromechanical actuators is proposed as morphing-enabling technology;the maturation process of the device is then traced from the proof of concept to the consolidation of a true-scale demonstrator for pre-flight ground validation tests.A step-by-step approach involving the design and testing of intermediate demonstrators is then carried out to show the compliance of the adaptive system with industrial standards and safety requirements.The technical issues encountered during the development of each intermediate demonstrator are critically analyzed,and justifications are provided for all the adopted engineering solutions.Finally,the layout of the true-scale demonstrator is presented,with emphasis on the architectural strengths,enabling the forthcoming validation in real operative conditions.
基金the Beijing Advanced Discipline Center for Unmanned Aircraft System。
文摘The morphing wing can improve the flight performance during different phases.However,research has been subject to limitations in aerodynamic characteristics of the morphing wing with a flexible leading-edge.The computational fluid dynamic method and dynamic mesh were used to simulate the continuous morphing of the flexible leading-edge.After comparing the steady aerodynamic characteristics of morphing and conventional wings,this study examined the unsteady aerodynamic characteristics of morphing wings with upward and downward deflections of the leading-edge at different frequencies.The numerical results show that for the steady aerodynamic,the leading-edge deflection mainly affects the stall characteristic.The downward deflection of the leading-edge increases the stall angle of attack and nose-down pitching moment.The results are opposite for the upward deflection.For the unsteady aerodynamic,at a small angle of attack,the transient lift coefficient of the upward deflection,growing with the increase of deflection frequency,is larger than that of the static case.The transient lift coefficient of the downward deflection,decreasing with the increase of deflection frequency,is smaller than that of the static case.However,at a large angle of attack,an opposite effect of deflection frequency on the transient lift coefficient was demonstrated.The transient lift coefficient is larger than that of the static case when the leading edge is in the nose-up stage,and lower than that of the static one in the nose-down stage.
基金This work is supported by the Major Program of National Natural Science Foundation of China(No.:NSFC51590892)the Shenzhen Municipal Science and Technology Innovation Commission of China(No.:JCYJ20160229165310679).
文摘Morphing technology is one of the most effective methods to improve the flight efficiency of aircraft.Traditional control surfaces based morphing method is mature and widely used on current civil and military aircraft,but insufficiently effective for the entire flight envelope.Recent research on morphing wing still faces the challenge that the skin material for morphing should be both deformable and stiff.In this study,a continuous morphing trailing-edge wing with a new multi-stable nano skin material fabricated using surface mechanical attrition treatment technology was proposed and designed.Computational fluid dynamics simulation was used to study the aerodynamic performance of the continuous morphing trailing-edge wing.Results show that the lift coefficient increases with the increase of deflection angle and so does the lift-drag ratio at a small angle of attack.More importantly,compared with the wing using flaps,the continuous morphing trailing-edge wing can reduce drag during the morphing process and its overall aerodynamic performance is improved at a large angle of attack range.Flow field analysis reveals that the continuous morphing method can delay flow separation in some situations.
基金co-supported by National Natural Science Foundation of China(Nos.50905085,91116020)National Science Foundation for Post-doctoral Scientists of China(No.2012M511263)
文摘A novel 0-Poisson＇s ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method （FEM） and experiments have been performed to validate the theoretical model. The in-plane characteristics of the cosine honeycomb are compared with accordion honeycomb through analytical models and experiments. Finally, the application of the cosine honeycomb on a variable camber wing is studied. Studies show that mechanical model agrees well with results of FEM and experiments. The transverse non-dimensional elastic modulus of the cosine honeycomb increases （decreases） when the wavelength or the wall width increases （decreases）, or when the amplitude decreases （increases）. Compared with accordion honeycomb, the transverse non-dimensional elastic modulus of the cosine honeycomb is smaller, which means the driving force is smaller and the power consumption is less during deformation. In addition, the cosine honeycomb can satisfy the deform- ing requirements of the variable camber wing.
基金co-supported by China Postdoctoral Science Foundation(Nos.20110490259,2012T50038)
文摘This article investigates gain self-scheduled H 1 robust control system design for a tailless fold- ing-wing morphing aircraft in the wing shape varying process. During the wing morphing phase, the aircraft＇s dynamic response will be governed by time-varying aerodynamic forces and moments. Nonlinear dynamic equations of the morphing aircraft are linearized by using Jacobian linearization approach, and a linear parameter varying （LPV） model of the morphing aircraft in wing folding is obtained. A multi-loop controller for the morphing aircraft is formulated to guarantee stability for the wing shape transition process. The proposed controller uses a set of inner-loop gains to provide stability using classical techniques, whereas a gain self-scheduled H 1 outer-loop controller is devised to guarantee a specific level of robust stability and performance for the time-varying dynamics. The closed-loop simulations show that speed and altitude vary slightly during the whole wing folding process, and they converge rapidly after the process ends. This proves that the gain self-scheduled H 1 robust controller can guarantee a satisfactory dynamic performance for the morphing aircraft during the whole wing shape transition process. Finally, the flight control system＇s robustness for the wing folding process is verified according to uncertainties of the aerodynamic parameters in the nonlinear model.
基金Bombardier AerospaceThales+1 种基金the Consortium for Research and Innovation in Aerospace in Quebec(CRIAQ)the National Sciences and Engineering Research Council(NSERC)for the funding received in connection with the CRIAQ MDO 505 project。
文摘The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale wing tip for a real aircraft equipped with an aileron.The morphing actuation of the model is based on a mechanism with four similar in house designed and manufactured actuators,positioned inside the wing on two parallel lines.Each of the four actuators used a BrushLess Direct Current(BLDC)electric motor integrated with a mechanical part performing the conversion of the angular displacements into linear displacements.The following have been chosen as successive steps in the design of the actuator control system:(A)Mathematical and software modelling of the actuator;(B)Design of the control system architecture and tuning using Internal Model Control(IMC)methodology;(C)Numerical simulation of the controlled actuator and its testing on bench and wind tunnel.The morphing wing experimental model is tested both at the laboratory level,with no airflow,to evaluate the components integration and the whole system functioning,but also in the wind tunnel,in the presence of airflow,to evaluate its behavior and the aerodynamic gain.
基金supported by National Natural Science Foundation of China (Grant No. 11102019)
文摘Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and control surfaces into a seamless wing and integrates the primary structure together with the internal control system.It makes use of the wing aeroelastic deformation induced by the control surface to gain direct force control through desirable redistribution of aerodynamic forces.However some unknown mechanical parameters of the control system and complexity of the integrated structure become a main challenge for dynamic modeling of morphing wing.To solve the problem,a method of test data based modal sensitivity analysis is presented to improve the morphing wing FE model by evaluating the unknown parameters and identifying the modeling boundary conditions.An innovative seamless morphing wing with the structure integrated with a flexible trailing edge control system is presented for the investigation.An experimental model of actuation system driven by a servo motor for the morphing wing is designed and established.By performing a vibration test and the proposed modal sensitivity analysis,the unknown torsional stiffness of the servo motor and the boundary condition of the actuation mechanism model is identified and evaluated.Comparing with the test data,the average error of the first four modal frequency of the improved FE model is reduced significantly to less than 4%.To further investigate the morphing wing modeling,a wing box and then a whole morphing wing model including the skin and integrated with the trailing edge actuation system are established and tested.By using the proposed method,the FE model is improved by relaxing the constraint between the skin and actuation mechanism.The results show that the average error of the first three modal frequency of the improved FE model is reduced to less than 6%.The research results demonstrate that the presented seamless morphing wing integrated with a flexible trailing edge control surface can improve aerodynamic characteristics.By using the test data based modal sensitivity analysis method,the unknown parameter and boundary condition of the actuation model can be determined to improve the FE model.The problem in dynamic modeling of high accuracy for a morphing wing can be solved in an effective manner.
