Wing Vibration Research Articles

Analysis of Tip Vortex Near-Wake Evolution for Stationary and Oscillating Wings

A numerical study is conducted to characterize the tip vortex unsteady evolution on a rounded-tip NACA0012 wing of aspect ratio operating at a Reynolds number of and an incidence of . Stationary and plunging wing configurations are examined as representative problems of aircraft wandering, wing vibration, or structural compliance that may all drastically affect the nature of the tip vortex and have important consequences in applications of formation flight, for instance. The high-frequency () low-amplitude () heaving motion of the wing promotes significant three-dimensionality of the overall flow structure with substantial variations in the tip vortex structure, including shear-layer substructure formation through enhanced separation and stretching, and alternating wakelike and jetlike behavior of its axial flow that leads to transitory enlargement or contraction of its core. The initial low-amplitude vertical displacement of the vortex grows dramatically as the structure advects into the wake, and a significant self-induced orbital motion results, which could be detrimental for downstream aerodynamic surfaces or for reliable vortex tracking in real-world applications. The dynamic state of the vortex as it leaves the wing is also shown to persist well into the wake.

A time-space synchronized fluid-structure coupling algorithm for the prediction of wing flutter

A fast dynamic mesh technology by our research group has been applied in the time synchronized fluid-structure coupling. It is found that flow mesh update after the convergent calculation of the flow will induce excessive iterations in the computation of flow increasing the computing time of fluid-structure coupling. To reduce the computing time, a time-space synchronized fluid-structure coupling algorithm was developed in this paper based on the pre-existing time synchronized method and the fast dynamic mesh technology. The wing vibration and flow mesh deformation were computed using the fast dynamic mesh technology after each iteration in the calculation of the flow. Namely, the flow and the wing vibration were solved in space synchronization. The calculating convergence of the flow and the wing vibration were both achieved through iterations every time step. Namely, the flow and the wing vibration were solved in time synchronization. Thus, the flow and the wing vibration are coupled both in time and space synchronization. The flutter boundary of wing 445.6 was predicted using the present algorithm. The calculated results compare well with the experimental data and the computing time was almost reduced by 75%.

Does indirect mating trophallaxis boost male mating success and female egg load in Mediterranean fruit flies?

Mating trophallaxis represents a fascinating strategy adopted by males of several animal species to affect the decision-making of females during mating. Among tephritids, few species perform mating trophallaxis. However, this phenomenon has been little studied in major tephritid pests. We reported the presence of indirect mating trophallaxis in Mediterranean fruit flies, Ceratitis capitata, showing its influence on the main mating traits, male mating success and female egg load. Of 219 mating pairs, only 27 of them showed mating trophallaxis, indicating that mating trophallaxis may represent a significant male energy investment. The duration of male wing vibration and the whole precopula phase was longer in pairs that mated without trophallaxis compared to the pairs displaying mating trophallaxis. Males that displayed trophallaxis performed a longer whole duration of the courtship and mating sequence, with no differences in copula duration. Male mating success was slightly increased by trophallaxis. The majority of males performing trophallaxis skipped wing vibration during courtship, while all males courting females without trophallaxis relied on wing vibration to attract females within short distances. No egg load differences were reported for females that consumed nuptial gifts over control females. Overall, our research sheds light on the relation between indirect mating trophallaxis and egg load production in medflies, providing a better understanding of sexual selective mechanisms as the basis of courtship and mating behaviour in tephritid flies. Furthermore, this behaviour could be used as a quality control parameter to assess medfly mass-reared strains, in order to improve sterile insect technique programmes.

Flutter suppression for highly flexible wings using passive and active piezoelectric effects

This paper addresses both active and passive flutter suppressions for highly flexible wings using piezoelectric transduction. An active aeroelastic formulation is used in the studies, featuring a geometrically nonlinear beam formulation coupled with 2-D unsteady aerodynamic equations. The piezoelectric effect is involved in the dynamic nonlinear beam equations, allowing for the aeroelastic studies on multifunctional wings for both piezoelectric energy harvesting and active actuation. In this study, the active piezoelectric actuation is applied as the primary approach for the flutter suppression, with the energy harvesting, as a secondary passive approach, concurrently working to provide an additional damping effect on the wing vibration. The multifunctional system may also convert wing vibration energy to electric energy as an additional function. Moreover, a Linear Quadratic Gaussian controller is developed for the active control of wing limit-cycle oscillations due to the flutter instability. In the numerical studies, both the active and passive flutter suppression approaches are enabled for a highly flexible wing. The impact of the piezoelectric actuator and energy harvester placement on the wing flutter characteristic is explored. This paper presents a comprehensive approach to effectively suppress the aeroelastic instability of highly flexible piezoelectric wings, while allowing to harvest the residual vibration energy. The active multifunctional wing technology that is explored in the paper has the potential to improve the aircraft performance from both aeroelastic stability and energy consumption aspects.

一様流中に置かれた弾性翼の自励振動と空力特性

一様流中に置かれた弾性翼の自励振動と空力特性

Gust load alleviation wind tunnel tests of a large-aspect-ratio flexible wing with piezoelectric control

An active control technique utilizing piezoelectric actuators to alleviate gust-response loads of a large-aspect-ratio flexible wing is investigated. Piezoelectric materials have been extensively used for active vibration control of engineering structures. In this paper, piezoelectric materials further attempt to suppress the vibration of the aeroelastic wing caused by gust. The motion equation of the flexible wing with piezoelectric patches is obtained by Hamilton’s principle with the modal approach, and then numerical gust responses are analyzed, based on which a gust load alleviation (GLA) control system is proposed. The gust load alleviation system employs classic proportional-integral-derivative (PID) controllers which treat piezoelectric patches as control actuators and acceleration as the feedback signal. By a numerical method, the control mechanism that piezoelectric actuators can be used to alleviate gust-response loads is also analyzed qualitatively. Furthermore, through low-speed wind tunnel tests, the effectiveness of the gust load alleviation active control technology is validated. The test results agree well with the numerical results. Test results show that at a certain frequency range, the control scheme can effectively alleviate the z and x wingtip accelerations and the root bending moment of the wing to a certain extent. The control system gives satisfying gust load alleviation efficacy with the reduction rate being generally over 20%.

Coupled fluid structure analysis for wing 445.6 flutter using a fast dynamic mesh technology

ABSTRACTThe flow around wing 445.6 was modelled using Navier–Stokes equations and S-A model. The wing vibration and flow mesh deformation were computed using a fast dynamic mesh technology proposed by our own group. Wing 445.6 flutter was analysed through a strong coupling between the wing vibration and flow. The reduced flutter velocity was predicted and results are in good agreement with the experimental data. It is found that the subsonic flutter is mainly induced by the flow separation and the transonic and supersonic flutter are mainly caused by the oscillating shock wave and its induced flow separation. The positive aerodynamic work increases due to the oscillating shock wave when the subsonic flow becomes transonic reducing the flutter velocity. While the positive aerodynamic work induced by the oscillating shock wave decreases when the transonic flow becomes supersonic increasing the flutter velocity. That is why the transonic dip exists.

Mating behavior of Psammotettix alienus (Hemiptera: Cicadellidae).

The Wheat dwarf virus, the causal agent of the wheat dwarf disease, is transmitted by leafhoppers from the genus Psammotettix and currently the main protection strategy is based on the use of insecticide treatments. Sustainable management strategies for insect vectors should include methods that are targeted to disrupt reproductive behavior and here we investigated the mating behavior of Psammotettix alineus (Dahlbom 1850) in order to determine the role of vibrational signals in intra-specific communication and pair formation. Both genders spontaneously emit species- and sex-specific calling songs that consisted of regularly repeated pulse trains and differ primarily in pulse train duration and pulse repetition time. Females preferred the conspecific male calling song. After a coordinated exchange of pulse trains, the male approached the stationary female. During the close range courtship and also immediately prior to copulatory attempts distinct male vibrational signals associated with wing flapping and wing vibrations were recorded from the substrate. In the presence of a receptive female, competing males emitted vibrational signals most likely aimed to interfere with male-female interaction. Mated females regained sexual receptivity after they laid eggs. Although results suggest that the viruliferous status of insects may have an effect on vibrational songs, our current results did not reveal a significant effect of virus on leafhopper performance in mating behavior. However, this study also suggests, that detailed understanding of plant-vector-virus interactions relevant for vector mating behavior is essential for trying new approaches in developing future control practices against plant viruses transmitted by insect vectors.

Concurrent Active Piezoelectric Control and Energy Harvesting of Highly Flexible Multifunctional Wings

Both active actuation and energy harvesting of highly flexible wings using piezoelectric transduction are studied in this paper. The piezoelectric effect is included in a strain-based geometrically nonlinear beam formulation. The resulting structural dynamic equations for multifunctional beams are then coupled with a finite-state unsteady aerodynamic formulation, allowing for piezoelectric energy harvesting and actuation with the nonlinear aeroelastic system. With the development, it is possible to provide an integral aeroelastic and electromechanical solution of concurrent active piezoelectric control and energy harvesting for wing vibrations, with the consideration of the geometrical nonlinear effects of slender multifunctional wings. In this paper, linear quadratic regulator and linear quadratic Gaussian controllers are developed for the active control of wing vibrations. The controllers demonstrate effective gust alleviation capabilities. Furthermore, concurrent active vibration control and energy harvesting can also be realized for the multifunctional wings with embedded piezoelectric materials. From this numerical study, the impact of the piezoelectric actuator and energy harvester placement on wing performance is benchmarked.

An energy method for flutter analysis of wing using one-way fluid structure coupling

In this paper, an energy method for flutter analysis of wing using one-way fluid structure coupling was developed. To consider the effect of wing vibration, Reynolds-averaged Navier–Stokes equations based on the arbitrary Lagrangian Eulerian coordinates were employed to model the flow. The flow mesh was updated using a fast dynamic mesh technology proposed by our research group. The pressure was calculated by solving the Reynolds-averaged Navier–Stokes equations through the SIMPLE algorithm with the updated flow mesh. The aerodynamic force for the wing was computed using the pressure on the wing surface. Then the aerodynamic damping of the wing vibration was computed. Finally, the flutter stability for the wing was decided according to whether the aerodynamic damping was positive or not. Considering the first four modes, the aerodynamic damping for wing 445.6 was calculated using the present method. The results show that the aerodynamic damping of the first mode is lower than the aerodynamic damping of higher order modes. The aerodynamic damping increases with the increase of the mode order. The flutter boundary for wing 445.6 was computed using the aerodynamic damping of the first mode in this paper. The calculated flutter boundary is consistent well with the experimental data.

Lekking Behaviour and Male-Male Rivalry in the Melon Fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae)

Most studies on the sexual behaviour of tephritid fruit flies are conducted in laboratory or field cage settings. Here, we present field data on the mating behaviour of the melon fly, Bactrocera cucurbitae (Coquillett). A number of Tephritidae are lekking species, forming aggregations in which males fight to defend a small territory where they court females and mate. Our results confirm that males of the melon flies congregated and engaged in wing vibration in the late afternoon on non-host plants, such as Ficus carica, Cydonia oblonga and Prunus persica which bordered cucurbit fields. The nature and outcome of male-male aggressive encounters are described, and a high degree of female mate selectivity is documented.

MODEL MATEMATIKA SEDERHANA REDAMAN GETARAN PADA SAYAP PESAWAT TERBANG

We have known that when the plane encountered turbulence or in a hard landing, the aircraft engine will swing to dampen vibrations of the aircraft wing. Thus, based on rights, this research is investigating and constructing mathematical model of aircraft wing vibration. In this research, we described not only the creation of mathematical models, but also the analysis of the model and its interpretation.

Nonlinear vibrations of a flexible membrane under periodic load

A finite element solution procedure is proposed, and the nonlinear vibrations of a flexible membrane under periodic load are investigated numerically. First, a simplified model is proposed for the flow-induced vibration of a membrane wing at higher angles of attack and the corresponding governing equation is derived briefly. Then, a solution procedure based on the Galerkin finite element method, Generalized- $$\upalpha $$ method and Newton–Raphson method is developed to solve the governing equation and its accuracy and stability are examined by a steady problem with exact solution. Finally, using the numerical method proposed, the forced vibration of a flexible membrane under periodic load is simulated, and the effects of the membrane density, elastic modulus and pre-strain are investigated in detail. In addition, the change in the vibration state along the membrane is also analysed to examine whether the centre point can reflect correctly the vibration state of the whole structure.

Modeling of Highly Flexible Multifunctional Wings for Energy Harvesting

In this paper, modeling of energy harvesting from transient vibrations of slender wings using piezoelectric transduction is implemented in a strain-based geometrically nonlinear beam formulation. The resulting structural dynamic equations for multifunctional beams are then coupled with a finite-state unsteady aerodynamic formulation, allowing for both energy harvesting and piezoelectric actuation with the nonlinear aeroelastic system. With the development, it is possible to provide an accurate, integral aeroelastic and electromechanical solution of both energy harvesting from and active control for wing vibrations, considering the geometrical nonlinear effects of slender wings. The current paper focuses on modeling the energy harvesting subsystem and exploring its impact on the multifunctional system. Vibrations of a slender multifunctional wing excited by both aeroelastic instability and external wind gusts will be considered as the sources of energy harvesting. All simulations will be completed in the time domain to accurately capture the nonlinear behaviors of the slender multifunctional wing. Based on the time-domain analysis, results of this effort illustrate that the piezoelectric energy harvesting from transient vibrations may provide adequate energy to support onboard sensor operations. In addition, results indicate that a well-tuned piezoelectric energy harvesting system may control the wing vibration using the shunt damping effect.

Effect of Inertial and Constitutive Properties on Body-Freedom Flutter for Flying Wings

The class of high-altitude long-endurance aircraft often has very slender wings with minimal structure. This leads to large trim deflections and coupling between the vehicle flight dynamics and wing vibrations. When this coupled behavior becomes unstable, it is referred to as body-freedom flutter. Body-freedom flutter behavior is dependent on the inertial and constitutive properties of the wing, as well as the fuselage. This relationship is explored for an aircraft representative of the Horten IV flying wing, using an efficient yet rigorous analysis that relies on geometrically exact, fully intrinsic beam equations and a finite-state induced flow model, which is implemented in the computer code NATASHA (which stands for nonlinear aeroelastic trim and stability of high-altitude long-endurance aircraft). The wing inertial and stiffness properties were calculated using a realistic representative section using the section analysis tool called variational asymptotic beam section analysis. Trade studies on the body-freedom flutter behavior were performed by varying the fuselage properties and the internal wing structure, as well as examining the effects on the flutter speed, flutter frequency, and flutter mode shape.

Effect of tip vortices on membrane vibration of flexible wings with different aspect ratios

In this study, the effect of the aspect ratio on the aerodynamics characteristic of flexible membrane wings with different aspect ratios (AR = 1 and AR = 3) is experimentally investigated at Reynolds number of 25000. Time accurate measurements of membrane deformation using Digital Image Correlation system (DIC) is carried out while normal forces of the wing will be measured by helping a load-cell system and flow on the wing was visualized by means of smoke wire technic. The characteristics of high aspect ratio wings are shown to be affected by leading edge separation bubbles at low Reynolds number. It is concluded that the camber of membrane wing excites the separated shear layer and this situation increases the lift coefficient relatively more as compared to rigid wings. In membrane wings with low aspect ratio, unsteadiness included tip vortices and vortex shedding, and the combination of tip vortices and vortex shedding causes complex unsteady deformations of these membrane wings. The characteristic of high aspect ratio wings was shown to be affected by leading edge separation bubbles at low Reynolds numbers whereas the deformations of flexible wing with low aspect ratio affected by tip vortices and leading edge separation bubbles.

Is bigger better? Male body size affects wing-borne courtship signals and mating success in the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae).

Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae). Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high-speed videos and analyzed through frame-by-frame analysis. Mating success of large and small males was investigated. The effect of male-male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing-borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no-competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high-frequency wing vibrations. Such traits may be indicative of "good genes," which under sexual selection could means good social-interaction genes, or a good competitive manipulator of conspecifics.

Nano-architecture of gustatory chemosensory bristles and trachea in Drosophila wings.

In the Drosophila wing anterior margin, the dendrites of gustatory neurons occupy the interior of thin and long bristles that present tiny pores at their extremities. Many attempts to measure ligand-evoked currents in insect wing gustatory neurons have been unsuccessful for technical reasons. The functions of this gustatory activity therefore remain elusive and controversial. To advance our knowledge on this understudied tissue, we investigated the architecture of the wing chemosensory bristles and wing trachea using Raman spectroscopy and fluorescence microscopy. We hypothesized that the wing gustatory hair, an open-ended capillary tube, and the wing trachea constitute biological systems similar to nano-porous materials. We present evidence that argues in favour of the existence of a layer or a bubble of air beneath the pore inside the gustatory hair. We demonstrate that these hollow hairs and wing tracheal tubes fulfil conditions for which the physics of fluids applied to open-ended capillaries and porous materials are relevant. We also document that the wing gustatory hair and tracheal architectures are capable of trapping volatile molecules from the environment, which might increase the efficiency of their spatial detection by way of wing vibrations or during flight.

스테레오 영상을 이용한 비행 중인 항공기 날개의 변위 및 진동 측정

The present study was conducted by using stereo pattern recognition method(SPR method) to measure the displacement and vibration of an airplane wing in flight condition. A SPR based measurement system was developed using two visible light stereo cameras. The visible light stereo images were processed to obtain marker points by adaptive threshold method and marker filtering technique. The marker points were used to reconstruct 3D point, displacement, and vibration data. The SPR system was installed on F-16 fighter. The wing displacement and vibration were measured in flight condition. Therefore, this paper presents a possibility that SPR based measurement system using visible light stereo camera can be very useful for measuring displacement and vibration of an airplane in flight condition.

Near wake dynamics around a vibrating airfoil by means of PIV and Oscillation Pattern Decomposition at Reynolds number of 65 000

Flow around steady and vibrating airfoil NACA 0012 with a 10° angle of attack has been studied experimentally, using a time-resolved PIV technique at Reynolds number of 65000. In this situation, a strong interaction between the airfoil and the flow-field is typically observed. Dynamics of flow in the airfoil wake has been investigated in details. Besides statistical analysis of the flow field point-by-point in space, we have explored complex spatial dynamics of the flow using the Oscillation Pattern Decomposition (OPD) method applied on the entire velocity vector field. The flow field spatial dynamics is characterized by the OPD modes of oscillating and non-oscillating characters, capturing traveling and pulsating patterns. Topology and frequencies of dynamical modes are to be shown. The unsteady velocity field is affected by both wing vibrations and inherent flow dynamics. Role of the airfoil vibrations in the flow dynamics is demonstrated.