Wing Configuration Research Articles

Multi-objective optimization and driving mechanism design for controllable wings of underwater gliders

Recently, underwater glider has become an effective tool for long-term ocean exploration. Controllable wing technology, which can improve comprehensive performance of underwater glider, has received widespread attention. This paper mainly proposes a multi-objective optimization based design method of controllable wings for underwater gliders. First, controllable wing configuration parameters are determined, specifically including wing span and sweep angle here. Then, hydrodynamic equations, containing controllable wing configuration parameters, are obtained by CFD simulation and quartic polynomial fitting. On this basis, the glider performance analysis model, quantitatively evaluating voyage velocity, static stability and energy consumption, are derived, and multi-objective optimization model of wing configuration parameters is established. Meanwhile, the relationship between controllable wing configuration parameters and the glider comprehensive performance is discussed. Especially, surrogate model technology is introduced into optimization calculation process to improve optimization efficiency. And non-dominated sorting genetic algorithm II is employed to obtain Pareto optimal set, which will make design objectives of driving mechanism of controllable wings clearer. Based on multi-objective optimization results and linkage synthesis method, a novel driving mechanism of controllable wings is designed, and corresponding principle prototype is manufactured. Besides, the motion characteristic, sealing and locking methods of the design scheme are also discussed.

Experimental Study of an Asymmetric Tandem Wing Configuration for Drone Application

A low-speed wind tunnel investigation characterizing the performance of an asymmetric tandem wing is presented. Wind tunnel data were supported by numerical modeling and flow visualization. The opposing wing halves of a rectangular AR=6.23 wing were systematically shifted fore and aft along a central fuselage to yield asymmetry. The results show that the lift curve slope, minimum drag coefficient, and Oswald efficiency factor are weakly affected by asymmetry, a result supported by numerical computations. The maximum lift-to-drag ratio, however, dropped essentially linearly with increasing asymmetry, a consequence of the reduced aspect ratio of each wing half decreasing the lift coefficient for minimum drag. Comparison of the experimental results with a symmetric wing with conventional empennage suggests that an asymmetric tandem wing configuration may be a viable geometry for deployable flight vehicles such as tube-launched drones.

Numerical analysis of pitch-break and all moving wingtip aileron of lambda wing configuration

Lambda wing, as a commonly used configuration for modern combat aircraft, tend to reduce stability margin known as Pitch-Break before the wing completely stalls. This phenomenon greatly affected the safety of aircraft at high angles of attack. In this paper, the characteristics of Pitch-Break are clarified and it is found that the initial airflow separation position of the outer wing is the principal reason for generating nonlinear moment of lambda wing. The airflow separation position is generally affected by leading edge vortex and the trailing edge spanwise airflow. Furthermore, the following conclusions are obtained: 1. The distribution of the absolute value of the leading edge radius is a decisive parameter of the initial position of leading edge vortex at the beginning of Pitch-Break zone; 2. The difference of trailing edge pressure gradient brings difference of trailing edge spanwise airflow at the end of Pitch-Break zone. To solve the aerodynamic problem of Pitch-Break, this paper adopts an all moving wingtip (AMT) as auxiliary aileron which has minor fluctuations during the Pitch-Break zone compared with conventional aileron. The result shows the defect of the conventional aileron pitch control at high angle of attack and presents the engineering feasibility of the all moving wingtip auxiliary aileron.

Review and aerodynamic analysis of NACA 2415 morphing wing for variable span and scale morphing concepts using CFD analysis

Morphing wings made a significant advancement in aircraft engineering by improving aerodynamic performance for better fuel efficiency and are still under research. This paper reviewed and investigated some morphing wing types including the variable sweep, trailing edge, leading edge, variable span, variable chord, or scale, and airfoil morphing among others. Based on the review, two types of morphing wings were chosen for detailed investigation, and they were variable span and variable scale. Each morphing concept from the selected morphing wing types was implemented in airfoil wing configuration for aerodynamic performance analysis. Computational Fluid Dynamics (CFD) simulation is used to design and analyse morphing wing configurations of the chosen morphing concepts. In this research, two CFD analyses were investigated based on wing configuration; each consists of chosen morphing concept. Before the main CFD simulation of morphing wing analysis, CFD analysis of reference data of a typical NACA 2415 airfoil was verified. The lift coefficient of the morphing wing obtained from CFD analysis was compared with the unmorphed NACA airfoil wing to evaluate the morphing wing’s aerodynamic performance. It is concluded that there is an improvement in lift coefficients using the morphing concept cases, showing improved aerodynamic performance.

Performance and Loads of a Wing-Offset Compound Helicopter

Analysis of a hingeless rotor with a single wing on the retreating side for lift compounding was conducted. The goals included validation of performance and load predictions with wind tunnel test data, study of the impact of different aerodynamic inflow models, and understanding of benefits by lift compounding with a single wing on the retreating side. The three primary test cases include collective sweeps of the isolated rotor, and the rotor with the wing, at two different incidence angles. The comprehensive analysis was able to accurately predict the performance and blade structural loads of both the isolated rotor and rotor plus wing configurations. Overprediction of propulsive force leads to underprediction of lift-to-drag ratio in several cases. The normal bending moments were well captured for all cases, while the chord bending moment predictions had a phase offset from the test data, but magnitude and harmonics were captured. Comparing inflow models found that dynamic inflow and vortex wake (prescribed and free) models provided similar results. At these advance ratios, prescribed and free wake models showed almost no differences. Additionally, the vortex particle method showed an overprediction of thrust and greater rotorto-wing aerodynamic interference compared to test data. The addition of the wing on the retreating side provided dual benefits of increasing maximum lift-to-drag ratio and reduction of structural loads for a given total thrust. These effects are a result of both lift share between the rotor and wing, and lift offset, the rotor carries a roll moment to balance the wing's roll moment.

Effects of Static Stability Margin on Aerodynamic Design Optimization of Truss-Braced Wing Aircraft

Currently, the aviation industry is facing an oil and energy crisis and is contributing much more greenhouse gas emissions to the environment. Aircraft design approaches, such as aerodynamic shape optimization, new configuration concepts, and active control technology, have been the primary and effective means of achieving goals concerning fuel burn, noise, and emissions. For now, the design problems of relaxed static stability (RSS, an active control technique) and truss-braced wing (TBW) configurations with high-fidelity aerodynamic shape optimization methods have been investigated widely to promote aerodynamic performance. Nevertheless, they are studied almost always separately, and the combination of exploration and refined design is rarely presented. Therefore, the purposes of this work are to evaluate the benefits of RSS on a full TBW wing–body–tail configuration under various flight conditions and the effects on multi-components and to further explore the potential and analyze the aerodynamic features with the combination of shape optimization and RSS. To address these issues, on the one hand, a range of seven static stability margins are adopted to evaluate its effects with a high-fidelity Reynolds-averaged Navier–Stokes solver. On the other hand, seven cases of drag minimization multipoint aerodynamic design optimization are performed, which are with 600 shape variables and 13 twist variables, subject to lift coefficient, trim, and thickness constraints. The results indicate that with RSS only, the initial configuration has a 2.39% drag reduction under cruise conditions and a 3.01% and a 5.24% drag reduction under two off-design conditions. Additionally, the effects on the multi-components are observed and analyzed. Moreover, all of the optimized configurations with RSS have 2.13%, 2.42%, and 2.12% drag reductions under cruise conditions, drag divergence conditions, and near-buffet-onset conditions, respectively. The most promising optimized configuration has a lift-to-drag ratio of 24.48 with an aerodynamic efficiency of 17.14. The evaluations with a series of off-design points also present high-level aerodynamic efficiency.

Role of the front wing/wheel setting-up on the optimal cornering performances of a Formula 1 car

We propose a hybrid approach based on meta-modelling techniques and machine-learning algorithms to determine the best car configuration for each circuit. By a specific interpolation model, we obtain an accurate estimation of the car’s speed as a function of the front wing configuration and the bend curvature. Some high-fidelity fluid dynamic simulations train the model and extend it to the entire design space. These data are then used as input for a simplified car dynamics model, providing an accurate estimate of the ideal lap time. Comparison with actual telemetry data confirms that the resulting tool is reliable, fast and easy to use.

Dynamic Structural Scaling Concept for a Delta Wing Wind Tunnel Configuration Using Additive Manufacturing

Considering aeroelastic effects plays a vital role in the aircraft design process. The construction of elastic wind tunnel models is a critical element in the investigation of occurring aeroelastic phenomena. However, the structural scaling between full-scale and reduced-scale configurations is a complex design and manufacturing task and is usually avoided in wind tunnel testing. This work proposes a numerical approach for a dynamic aeroelastic scaling technique, which is applied to a fictive delta wing configuration. This scaling methodology is designed to optimise the structural layout of wind tunnel models with an integrated rib and spar structure to meet the behaviour of a realistic full-scale equivalent. For the modelling approach of the wing structure, a beam and shell structure is utilised. The applied scaling laws for the relevant quantities and the applied procedures are described. Computational fluid dynamics (CFD) calculations are performed by solving the Reynolds-averaged Navier–Stokes (RANS) equations for the assumption of a rigid full-scale and down-scaled wing. These calculations are used to verify the aerodynamic scaling assumptions, which are applied to the scaling procedure of the wind tunnel model. Global aerodynamic coefficients are evaluated for a variety of angles of attack. The local flow phenomena of the full-scale and the scaled model are compared in more detail for a medium and a high angle of attack. The pressure coefficient distribution shows a proper accordance for the full-scale and the scaled model. To verify the results of the structural scaling optimisation, a high-fidelity structural full-scale model is compared with the scaled model using the ELFINI FEM solver. Therefore, all structural components are modelled by 2D elements. The results for the reduced eigenfrequencies and according modes of the full-scale and the scaled model show a high level of similarity. A static deformation of the structural grids is performed by applying the aerodynamic loads from the CFD simulations. The results show that the deviation of the nondimensional deformation between the scaled and the full-scale model is negligible. Consequently, the applied scaling methodology proves to be a valuable tool for the conceptual approach of designing aeroelastically scaled wind tunnel models considering 3D-printed material.

Multidisciplinary structural optimization of novel high-aspect ratio composite aircraft wings

Novel high-aspect ratio airframe designs pave the way for a more sustainable aviation future. Such configurations enhance the aerodynamic efficiency of an aircraft through induced drag reduction mechanisms. Further performance gains, mainly in terms of structural mass, are accomplished via composite materials airframes. Nevertheless, undesired phenomena such as geometric nonlinearities and aeroelastic couplings due to elevated flexibility may often rise, rendering the design and optimization of such airframes extremely intricate and prohibitive in terms of computational cost. Low-fidelity tools, often preferred on the early design stages, accelerate the design process, albeit suffering from reduced accuracy and ability to capture higher-order phenomena. Contrastingly, high-fidelity computational methods incur excessive computational cost and are therefore utilized at the later, detailed design stages. There arises, therefore, the need for a combination of the various fidelities involved in a cost-effective manner, in order to drive the design towards optimal configurations without significant performance losses. In our approach, variable fidelity analyses are initially conducted in order to shed light on their effect on the structural response of a high-aspect ratio composite materials reference wing. An optimization framework combining low and high-fidelity tools in a sequential manner is then proposed, aiming at attaining a minimum mass configuration subject to multidisciplinary design constraints. As demonstrated, reasonable mass reduction was obtained for a future aircraft wing configuration.

Wake tail plane interactions for a tandem wing configuration in high-speed stall conditions

In this work, wake-tail plane interactions are investigated for a tandem wing configuration in buffet conditions, consisting of two untapered and unswept wing segments, using hybrid Reynolds-Averaged Navier–Stokes / Large Eddy Simulations (RANS/LES) with the Automated Zonal Detached Eddy Simulation (AZDES) method. The buffet on the front wing and the development of its turbulent wake are characterized, including a spectral analysis of the fluctuations in the wake and a modal analysis of the flow. The impact of the wake on the aerodynamics and loads of the rear wing is then studied, with a spectral analysis of its lift and surface pressure oscillations. Finally, the influence of the position and the incidence angle of the rear wing is investigated. For the considered flow conditions, 2D buffet is present on the front wing. During the downstream movement of the shock, the amount of separation reaches its minimum and small vortices are present in the wake. During the upstream movement of the shock, the amount of separation is at its maximum and large turbulent structures are present accompanied by high fluctuation levels. A distinct peak in the corresponding spectra can be associated with vortex shedding behind the wing. The impingement of the wake leads to a strong variation of the loading of the rear wing. A low-frequent oscillation of the lift, attributed to the change of the intensity of the downwash generated by the front segment, can be distinguished from high-frequent fluctuations that are caused by the impingement of the wake’s turbulent structures.

Analysis of longitudinal dynamic stability of tandem wing aircraft

PurposeTandem wing aircrafts belong to an unconventional configurations group, and this type of design is characterised by a strong aerodynamic coupling, which results in lower induced drag. The purpose of this paper is to determine whether a certain trend in the wingspan impact on aircraft dynamic stability can be identified. The secondary goal was to compare the response to control of flaps placed on a front and rear wing.Design/methodology/approachThe aerodynamic data and control derivatives were obtained from the computational fluid dynamics computations performed by the MGAERO software. The equations of aircraft longitudinal motion in a state space form were used. The equations were built based on the aerodynamic coefficients, stability and control derivatives. The analysis of the dynamic stability was done in the MATLAB by solving the eigenvalue problem. The response to control was computed by the step response method using MATLAB.FindingsThe results of this study showed that because of a strong aerodynamic coupling, a nonlinear relation between the wing size and aircraft dynamic stability proprieties was observed. In the case of the flap deflection, stronger oscillation was observed for the front flap.Originality/valueResults of dynamic stability of aircraft in the tandem wing configuration can be found in the literature, but those studies show outcomes of a single configuration, while this paper presents a comprehensive investigation into the impact of wingspan on aircraft dynamic stability. The results reveal that because of a strong aerodynamic coupling, the relation between the span factor and dynamic stability is nonlinear. Also, it has been demonstrated that the configuration of two wings with the same span is not the optimal one from the aerodynamic point of view.

Nonintrusive Aerodynamic Shape Optimisation with a POD-DEIM Based Trust Region Method

This work presents a strategy to build reduced-order models suitable for aerodynamic shape optimisation, resulting in a multifidelity optimisation framework. A reduced-order model (ROM) based on a discrete empirical interpolation (DEIM) method is employed in lieu of computational fluid dynamics (CFD) solvers for fast, nonlinear, aerodynamic modelling. The DEIM builds a set of interpolation points that allows it to reconstruct the flow fields from sets of basis obtained by proper orthogonal decomposition of a matrix of snapshots. The aerodynamic reduced-order model is completed by introducing a nonlinear mapping function between surface deformation and the DEIM interpolation points. The optimisation problem is managed by a trust region algorithm linking the multiple-fidelity solvers, with each subproblem solved using a gradient-based algorithm. The design space is initially restricted; as the optimisation trajectory evolves, new samples enrich the ROM. The proposed methodology is evaluated using a series of transonic viscous test cases based on wing configurations. Results show that for cases with a moderate number of design variables, the approach proposed is competitive with state-of-the-art gradient-based methods; in addition, the use of trust region methodology mitigates the likelihood of the optimiser converging to, shallower, local minima.

Vortex Interaction Characteristics of Multiswept Wings at Subsonic Speeds

Despite the sufficient knowledge on the physics of vortices formed over slender delta wings, there is a lack of understanding about how corotating and counter-rotating vortices near the wing leading edge interact with each other. The vortex interaction will depend on the wing planform, leading-edge sweeps, leading-edge shapes, angle of attack, angle of sideslip, and the Reynolds number. In this study, experiments were performed on a range of planform configurations to determine the influence of multisweep wing configurations on the vortex interactions and breakdown thereof. Force/moment measurements were conducted to understand globally the effect of the planform configuration, whereas particle tracking surface oil flow and stereoscopic particle image velocimetry were employed to detect interactions locally in the flowfield. Results were validated against corresponding numerical simulations and past experiments. Comprehensive results indicated a strong correlation between the chord ratios of the initial sweep on the suppression of vortex breakdown. Specifically, two cases with varying chord ratios were identified that exhibited unique vortex breakdown progression (gradual and rapid). Flowfield measurements elucidated key flow features responsible for the differing breakdown progression.

The aerodynamic behavioral study of canard plane with fan wing configuration

This study explores the optimization of the canard aerodynamic scheme by integrating wing-mounted propulsion systems to enhance efficiency. Key objectives include stability, controllability, and reducing frontal air resistance by employing an advanced aerodynamic scheme that effectively utilizes the wake filling phenomenon behind the wing when integrated with wing-mounted propulsion. The study emphasizes strategic design considerations for the wing, fuselage, and adjacent aerodynamic surfaces, which can enhance aerodynamic characteristics. Preserving the Coanda effect creates a low-pressure zone, improving overall efficiency. The paper underscores the importance of lightweight construction for safety and reliability. Numerical modeling underscores the need for physical experiments to validate results. Experimental simulations indicate possibilities for stable and controlled flight. Lightweight, reliable designs, and cutting-edge aerodynamic concepts offer prospects for improved efficiency and flight productivity.

Aerodynamic Exploration for Tandem Wings with Smooth or Corrugated Surfaces at Low Reynolds Number

Skin corrugation and tandem configuration are two distinct features that characterize the flow around dragonfly wings. In contrast to the smooth airfoil and single pair of wings of conventional airplanes, corrugated surfaces and tandem wings influence aerodynamics both locally and globally. In this article, several kinds of doubly- tandem wing configurations were designed, then computational investigations based on wind tunnel experiments were conducted to investigate the aerodynamic characteristics of these models. Computational simulations using in-house codes were carried out with a freestream velocity of 20 m/s at an angle of attack from −4° to 16°. Based on these computational results, the effects of airfoil thickness, surface waviness and hindwing decalage on aerodynamic characteristics were compared and presented quantitatively. Final results demonstrate that a tandem wing configuration could eliminate separation close to the trailing edge at angles of attack 8°~10°, or delay the trailing edge separation at angles of attack greater than 10°. Thus, the aerodynamic efficiency of tandem configurations could provide significant improvement compared to configurations with a single wing. The greatest percentage of aerodynamic efficiency improvement for a tandem thick configuration compared to a single thick configuration is 1376% at angle of attack 0°. Surface waviness will stall at a lower angle of attack, but will gain some aerodynamic benefit from the standing separated flow. Hindwing decalage has obvious lift enhancement for the tandem configuration. Therefore, it is concluded that the tandem configuration is attractive and promising for MAVs with flexible structures in the near future.

Numerical Study on Fluid Dynamic Characteristics of a Cross-Flow Fan

This paper focuses on the application of a cross-flow fan (CFF) to generate propulsion for a submersible aircraft with a flying wing configuration. A numerical method is established to simulate the CFF operating both in the air and underwater. This paper then investigates the fluid dynamic characteristics of the CFF, including the velocity field, the pressure field, the cavitation distribution, the lift, and the thrust. It is concluded that proper lifts and thrusts can be obtained when the rotating speed and the angle of attack are reasonably designed. This work provides a valuable numerical methodology for studying the fluid dynamic characteristics of the CFF operating in different media and offers a technical basis for the selection of a motor system for submersible aircraft.

Design and Optimization of Wing Internal Structure to Study the Flutter Frequency of Aircraft Wing

The field of aviation has reached a lot of milestones in the 19th and early 20th century, but the supersonic commercial flights are still a nightmare in 21st century. The major obstacle to reach this milestone is the effect of flutter, which is an aeroelastic phenomenon. It is very important to understand the effect of flutter to reduce it. In this paper effect of flutter is studied by varying the wing internal structures. A scaled down model of the AGARD 445.6 wing having 65A004 aerofoil is designed using Catia V5, for which the experimental data is available for validation. Grid independence study is carried out to obtain more reliable mesh quality. Since flutter is a transient phenomenon time-step independence study is carried out for the time steps of, 0.005s, 0.0025s and 0.00125s. Since there is no difference between the flutter frequency readings for 0.0025 seconds and 0.00125 seconds, 0.0025 seconds is chosen to reduce the computation time. The baseline case is validated with an experimental data available and an error of 0.2-5.32% is observed. Aircraft wing is mainly made out of aluminium alloys. Hence a suitable aluminium alloy is selected by comparing the flutter frequencies. To choose a suitable material, three materials each from wood, alloys and composite are considered i.e., mahogany, aluminium alloy 7075 T6 and Aluminium Metal Matrix Composite (AMC) which are widely used in the Aviation industry. AMC is considered on the basis of frequency charts whose flutter frequency is 30Hz. In this paper in order to supress the flutter we have introduced optimization of ribs and spars in the wing. Variation in the number of ribs, flange width and rib thickness are considered individually. Wing configuration with 10 ribs, flange width of +10% and 10mm rib thickness respectively are having the best flutter frequencies. The wing with above features is further optimised by keeping weight as a constraint by introducing circular and triangular cut-outs section. Flutter frequency for without cut-out, circular cut-out and triangular cut-out are 77.84 Hz, 78.27Hz and 78.43Hz respectively. Hence it is concluded that ribs with triangular cut-outs can be able to reach maximum flutter frequency.

Flow Field Investigation of a Blended Wing Body in Low Speeds

With the advancement in the modern transport system, it has become imperative to achieve larger aircraft volume at minimum cost wherein aerodynamics plays a major role. The present work aims to investigate the flow over a typical blended wing body (BWB) configuration at different angles of attack adopting experimental and computational techniques. Experiments consisted of the force measurements and oil flow visualizations at a free stream velocity of around 19 m/s. Computations were made using the commercially available software ANSYS 18.1. Results indicated that the use of a Blended Wing Body Configuration resulted in improved aerodynamic characteristics in comparison to other wing configurations such as Delta/ Double delta wings. Surface flow visualization carried out over the BWB configuration indicated the reason behind increased lift coefficients. Reasonable agreement of experiments and computations was observed.

Failure Initiation Analysis of a PRSEUS BWB Wing Subjected to Structural Damage

In this study, a finite element approach was used to analyze the PRSEUS-based undamaged wing structure of a civil aircraft with a blended-wing-body configuration. The displacement, stress, and strain distribution of the PRSEUS wing structure were studied under an aerodynamic load with three different values of the factor of safety. This was used as a reference to study the response of the same wing configuration, first with a single stringer, where failure was initiated at the fourth loading value, while the second loading condition was sufficient to initiate failure in the triple-stringer damage wing. In addition, damage to rib components was investigated, and it was shown that damage to a single rib and double rib did not impose significant risks to the structural integrity of the wing structure, and the results have shown that the values of displacement, stress, and strain do not differ much from those of the undamaged wing, even as the length of the rib damage is increased.

Beyond imaging: drones for physical applications

PurposeThis paper aims to illustrate the growing role of drones in applications involving physical tasks.Design/methodology/approachFollowing a short introduction, this first provides a brief introduction to drone technology. It then describes and discusses products and applications involving physical tasks in agricultural and forestry, maritime rescue, firefighting and product delivery. Finally, brief conclusions are drawn.FindingsExcluding military applications, drones were initially used primarily for image acquisition. Numerous different designs have since been developed with greatly varying wing configurations, payloads, flight duration, power sources and other features which are increasingly being used to conduct physical tasks. In the applications considered here drones are applying agrochemicals and dispersing crop and tree seeds; saving lives by deploying lifeboats and buoyancy aids; extinguishing fires in high-rise buildings and forests; and delivering groceries, food, mail, medicines and humanitarian aid, often in and to remote locations.Originality/valueThis study provides a detailed insight into selection of applications in which drones conduct physical tasks.