Aircraft Wing Design Research Articles

On the Incipient Indicial Lift of Thin Wings in Subsonic Flow: Acoustic Wave Theory with Unsteady Three-Dimensional Effects

Enhanced approximate expressions for the incipient indicial lift of thin wings in subsonic potential flow are presented in this study, featuring explicit analytical corrections for the unsteady downwash. Lifting-line and acoustic-wave theories form the basis of the method, within an effective synthesis of the governing physics, which grants a consistent generalised framework and unifies previous works. The unsteady flow perturbation consists of a step-change in angle of attack or a vertical sharp-edged gust. The proposed model is successfully evaluated against numerical results in the literature for the initial airload development of elliptical and rectangular wings with a symmetric aerofoil, considering several aspect ratios and Mach numbers. While nonlinear downwash and compressibility terms demonstrate marginal (especially for the case of a travelling gust), both linear and nonlinear geometrical effects from a significant taper ratio, sweep angle or curved leading-edge are found to be more important than linear downwash corrections (which are crucial for the circulation growth at later times instead, along with linear compressibility corrections). The present formulae may then be used as a rigorous reduced-order model for validating higher-fidelity tools and complex simulations in industrial practice, as well as for estimating parametric sensitivities of unsteady aerodynamic loads within the preliminary design of aircraft wings in the subsonic regime.

Numerical investigation of aerodynamic performance of leading edge tubercle airfoil at low Reynolds number

Numerical investigation was made to study the aerodynamic characteristics of the Tubercle NACA2412 airfoil is used in the design of aircraft wing and wind turbine blades. In this paper, computational study aimed to observe the aerodynamic characteristics of 3D airfoil NACA 2412 with peak and trough chord length as 100 mm and 80 mm respectively. The co-efficient of pressure performance of NACA2412 airfoil with tubercle leading edge profile blade used to investigate numerically for enhance the aerodynamics performance of Wind turbine. Investigation were made to find pressure distribution over the Tubercle airfoils under various freestream velocity conditions such as 5 m/s, 10 m/s, 15 m/s and 20 m/s with different angle of attacks from −30° to 30° with the step of 5°. The Spalart–Allmaras turbulent model was used to carry out simulations in the ANSYS Fluent software. Therefore, the Coefficient of pressure distribution is calculated at peak and trough of the tubercle airfoil at different operating conditions and results are plotted in the graph. It is observed that pressure distribution varies drastically near the leading edge for all velocities. Analysis for different velocities with a wide range of angle of attacks are discussed and presented with relevant details.

A Dynamic Programming Approach to the Design of Composite Aircraft Wings

A light and reliable aircraft has been the major goal of aircraft designers. It is imperative to design the aircraft wing skins as efficiently as possible since the wing skins comprise more than fifty percent of the structural weight of the aircraft wing. The aircraft wing skin consists of many different types of material and thickness configurations at various locations. Selecting a thickness for each location is perhaps the most significant design task. In this paper, we formulate discrete mathematical programming models to determine the optimal thicknesses for three different criteria: maximize reliability, minimize weight, and achieve a trade-off between maximizing reliability and minimizing weight. These three model formulations are generalized discrete resource-allocation problems, which lend themselves well to the dynamic programming approach. Consequently, we use the dynamic programming method to solve these model formulations. To illustrate our approach, an example is solved in which dynamic programming yields a minimum weight design as well as a trade-off curve for weight versus reliability for an aircraft wing with thirty locations (or panels) and fourteen thickness choices for each location.

Structural Design and Analysis of a Light Aircraft Wing

The aim of this study is to perform structural design and analysis of a light aircraft wing. Both aerodynamic analysis and structural design of the wing are covered. The aerodynamic analysis is achieved by using Schrenks Approximation Method simulated in MATLAB to estimate the lift distribution. In addition, static stress analysis of the wing is carried out to compute the stresses at wing structure when subjected to the generated aerodynamic loads and thereby examine its structural reliability. The stresses are estimated by using the finite element software package MSC/NASTRAN/PATRAN. A maximum Von Mises stress of 135MPa is obtained which is less than the yield stress for aluminum alloy used in wing design. On the other hand, and based on the finite element model, a free-vibration analysis is performed for the whole model. The frequencies for the first three modes and the corresponding mode shapes are presented. The purpose of this study is to correlate and validate the finite element model against the modal test in preparation for further complex analysis. The finite element results have shown that the suggested wing configuration of the light aircraft is safe, with margins of safety equal to 1.33 which occurs at the root section.

Hybridised differential evolution and equilibrium optimiser with learning parameters for mechanical and aircraft wing design

Metaheuristics (MHs) have been widely used for aeroelastic optimisation of aircraft wings and other types of aircraft structures. Using such methods offers some advantages e.g. flexibility for coding, robustness, global optimisation capability, and a derivative-free feature. Moreover, unconventional design problems can be posed when using metaheuristics. This paper proposes a new hybrid algorithm, named HDEEO-LP, with a learning control parameter for aeroelastic optimisation. The new optimiser is obtained from hybridising differential evolution and the recently invented equilibrium optimisation, while a learning scheme for control parameter tuning is integrated. The new method is tested against a number of established and recently invented MHs, such as a grey wolf optimiser (GWO), a salp swarm algorithm (SSA), an equilibrium optimiser (EO), an artificial bee colony (ABC), teaching–learning based optimisation (TLBO), water cycle algorithm (WCA), self-adaptive spherical search algorithm (SASS) using the CEC-RW-2020 test suite and the Goland wing aeroelastic optimisation. The results reveal that the proposed hybrid algorithm is among the top performers.

Korozja pokrycia samolotu i względy bezpieczeństwa konstrukcyjnego

The aim of this article is to point out some peculiarities of airframe corrosion, the impact of external forces on aircraft skin elements and their impact on structural integrity. The corrosion process is generally associated with fatigue of aircraft structural elements due to the effect of many factors such as the type of loading, the properties of the materials, the corro-sive environment, etc. The article is not focused on corrosion processes, but on load factors that are specific to aircraft wing design elements and their influence on corrosion of critical struc-tural elements. Corrosion of the wing is perceived as a consequence of environmental impact on damaged surface protection of the skin and connecting parts (rivets, screws, and welded joints) caused by static and dynamic stress of the wing and also by the interaction of the indi-vidual structural elements as a whole. The dynamics of operation of individual structural ele-ments is further enhanced by the fatigue of the material. Early detection of corrosion processes has generally been and is crucial to overall safety of the aircraft. The proposals presented in the article are formulated in order to improve the system of work to ensure the safety of aircraft operation in terms of resistance to corrosion damage.

Normal stress flow evaluation in composite aircraft wing sections by strength of material models

The increasingly widespread use of composite materials in structural elements of commercial aircrafts (Airbus 350, Boeing 787), has led to consider the design of wings in composite material. Finite Element (FE) models have been used as a numerical tool for analysis and design, due to the geometrical complexity of these elements, together with the anisotropic nature of the composite material. However, the structural design of elements made of composite laminates using FE models is very expensive in terms of time needed for processing the results and for introducing modifications. The use of simpler Strength of Materials (SM) models has shown to be very efficient for the design of wind turbine blades.The objective of this work is to investigate the feasibility of using these SM models for composite layered aircraft wing design. To this end, a specific model that considers the geometric characteristics of these structural elements (multicellular sections and presence of longitudinal spars and transverse stiffeners) has been developed. The application of the SM model on a specific geometry of a wing torsion box under a given loading condition has allowed us to successfully compare the results, in terms of longitudinal stress flows, with those obtained by a numerical FE model for the same problem, using equivalent discretization.

Multi-objective aerodynamic optimization design of variable camber leading and trailing edge of airfoil

Variable camber is an effective method for improving the flight efficiency of large aircraft, and has attracted the attention of researchers. This work focused on the optimization of a variable camber airfoil. First, the influences of the variable camber of the leading and trailing edges on the airfoil aerodynamic performance were investigated using a computational fluid dynamics numerical simulation. An initial database was established for a deep neural network. Second, an iterative algorithm was constructed to optimize the variable camber airfoil in terms of the rotation angle of the leading edge, deflection position of the leading edge, rotation angle of the trailing edge, and deflection position of the trailing edge. A genetic algorithm was used in each iteration to maximize the lift coefficient and lift-to-drag ratio, as predicted using a deep neural network (DNN). The optimal results were validated using Fluent. If the DNN result approximated the Fluent results, the iterative process was stopped. Otherwise, the Fluent results were inserted into the database to update the DNN prediction model. The optimization results showed that the lift-to-drag ratio of the 2D airfoil could be increased by more than 14 when the angle of attack was less than 8° relative to the original airfoil. Furthermore, to validate the 2D optimal results, the optimized 2D airfoil was stretched into 3D, and it was discovered that the aerodynamic performance trend of the 3D airfoil with respect to the angle of attack was basically the same as that of the 2D airfoil. In addition, the corresponding 3D airfoil improved the aerodynamic performance and reduced the noise at a high frequency (by approximately 16 dB). In contrast, the noise in the low and medium frequencies remained unchanged. Therefore, the optimization method and results can provide a reference for the aerodynamic design and acoustic design of large civil aircraft wings.

CFD (Computational Fluid Dynamics) Modeling on Narasena Bengawan UV Team Quickster UAV Wings with Addition of Vortex Generator to Aerodynamic Performance

This research is based on obtaining the best possible aerodynamic performance for the Quickster Narasena Bengawan UV Team UAV aircraft wing design. One of the factors that greatly affects the flying performance of a UAV is the wing. The wing on the Quickster Narasena UAV aircraft uses an MH33 airfoil, because MH33 is specifically for high-speed UAV aircraft. This research will discuss the comparison of the performance of a wing without a vortex generator with a wing with a vortex generator. Variations in the positioning of the vortex generator on the wing of the Quickster Narasena UAV will also be discussed in this study. The method used in this research is the CFD (Computational Fluid Dynamics) method. The simulation process will use the ANSYS Fluent 19.0 application with the K-Omega SST method with the Reynolds-Averaged-Navier-Stokes (RANS) equation as the basis. The purpose of this study is to obtain the results of the coefficient of drag, lift, and the contour of the turbulence that will occur. The simulation results that have been done are the geometry of the wing with the addition of a vortex generator can reduce the drag coefficient and can increase the lift coefficient.

Aeroelastic optimisation of manufacturable tow-steered composite wings with cruise shape constraint and gust loads

In the structural design of aircraft wings, aeroelastic tailoring is used to control the aeroelastic deformation to improve the aerostructural performance by making use of directional stiffness. Recently, tow-steered composites, where the fibre angles continuously vary within each ply, have been proven to have the potential to further expand the advantages of aeroelastic tailoring. This work extends TU Delft aeroelastic tailoring framework PROTEUS by introducing a lay-up retrieval step, so that it can be used for the conceptual design of tow-steered composite wing structures. In the extended framework, aeroelastic tailoring and lay-up retrieval are sequentially and iteratively performed to take static and dynamic loads, manufacturing and cruise shape constraints into consideration. The first step is carried out using PROTEUS, in which the lamination parameters and thickness of the wing sections are optimised under manoeuvre and gust load conditions. Further, for ensuring optimal aircraft performance in cruise flight conditions, the jig twist distribution is allowed to be optimised to maintain a desired prescribed cruise shape. In the second step, the stacking sequence, including minimum steering radius constraint, is retrieved. Since the lamination parameters cannot be matched exactly during the retrieval step, the constraints are checked, and tightened to take the performance loss during retrieval into account. The first step is repeated until all constraints are satisfied after fibre angle retrieval. To demonstrate the usefulness of the proposed optimisation framework, it is applied to the design of the NASA Common Research Model (CRM) wing, of which the objective is minimizing wing mass subjected to aerostructural design constraints, such as aeroelastic stability, aileron effectiveness, material strength and buckling load.

On the controlled evolution for wingtip vortices of a flapping wing model at bird scale

The reduction of wingtip vortices is a critical and challenging task for aircraft wing-design. Inspired by the wingtip morphology of soaring birds, Whitcomb created winglets to reduce the drag of commercial airplanes significantly. As a critical feature of bird flight, the dynamic flapping wing motion could potentially affect the evolution of tip vortices, which has been rarely investigated. To explore the control mechanisms of wingtip vortices by flapping, a flapping wing model with two-jointed arms was designed to mimic geese's flapping motion. The evolution of tip vortices was recorded in a wind tunnel using particle image velocimetry (PIV) system, and physical features were analyzed. It is shown that wingtip vortices change the vorticity concentration and vortex radius as wings flap in a cycle. The continuous coherent streamwise structure could pinch off at the upstroke end. As flapping frequency increases, the vorticity-concentrated tip vortices become dispersed. Circulation change in a cycle is dramatic, and the tip vortices present a directly up- and downward movement, which indicates a wave-like trajectory. Flapping induces the wingtip vortices to wander in a large amplitude and a specific direction instead of randomly in a limited region. Proper orthogonal decomposition (POD) results show that flapping can not only affect the vorticity concentration and radius of tip vortices as well as energy contribution of the first mode, but also increase the energy contribution and induce the coherent field of the second mode into a time-dependent vortex pair. The relative energy contribution and direction of the vortex pair vary with flapping motion, which affects the wandering amplitude and direction. It is suggested that flapping can break up the vorticity-concentrated wingtip vortices, and give them ordered evolution trajectory and directional wandering motion, which could shed light on the effective vortex control and drag reduction for aircraft wing-design.

Comparative study on vibration characteristics of aircraft wings using finite element method

In recent times, there has been significant research in the area of vibration in aircraft wings. Vibration can cause some serious failure in the structure. The increase in research in vibration has led to taking design considerations in the wings. This paper specifically focuses on the vibration in wings. Modal analysis of wing with the rectangular cross section is done with the use of Finite Element Analysis. Three different materials (Aluminum, Carbon Fiber and E-glass Fiber) have been incorporated which describe the effect of free vibration. The results show that Aluminum 2024 is best suited for the design of aircraft wings compared to other two materials.

Reliability-based Design Optimization of Classical Wing Aeroelasticity

Flutter speed of aircraft is very important and needs to be firstly specified before a certification applied for a new aircraft by airworthiness regulator to make sure that the aircraft is free from flutter in its flight envelope. By assuming geometrical and physical parameters known, the speed is usually estimated from deterministic analyses in a design stage. In practice, some parameters are finitely measured by observing, especially for the geometrical parameters, material properties and so on due to the random in nature, which causes uncertainty of information often called uncertainties. The purpose of this paper is to combine reliability analysis and optimum design of aeroelastic aircraft wing. The classical two-dimensional wing with a typical airfoil section is used as an example in this study. To quantify uncertainty in the design of flutter speed, the discrete-time aero-elastic model and worst-case scenario are applied. Furthermore, the comparison between optimum design with/without reliability is provided in this study. The results show the proposed technique leads to the flutter speed being more conservative and realizable compared with the traditional technique.

Controllability Gramian as Control Design Objective in Aircraft Structural Design Optimization

Because of their higher aerodynamic efficiency and lighter structural weight, thin composite wings with large aspect ratios are increasingly being used for civil transport aircraft wing design. However, the increased flexibility can induce several performance issues, such as high deflections, reduced control authority, coupled flight dynamics, and, possibly, a reduction in the flutter speed. Therefore, including control surface and control law design at the conceptual design stage is becoming increasingly important. This paper presents a novel approach for integrating a control objective into an aircraft design optimization at the conceptual design stage by proposing the use of the eigenvalues of the controllability Gramian to enhance the controllability of an aircraft. The individual eigenvalues of the controllability Gramian quantify the energy required to move along the corresponding eigenvector, which is observed to be dominated by one state-space variable. A higher eigenvalue implies lower energy requirements for controlling that eigenvector, thus the corresponding state-space variable. This approach does not rely on a control law design but on modifying the open-loop system such that it is easier to control. The approach is applied to conduct multidisciplinary design analysis and optimization (MDAO) of a composite flying-wing test aircraft. A previously developed MDAO framework is used to design the internal structural layout, using curvilinear spars and ribs (SpaRibs) and straight spars and ribs. It is found that the optimal control designs have up to 8% higher flutter speed with a 3.7% weight penalty. Moreover, the frequencies of the vibration mode shapes are higher for the optimal control designs. The active flutter suppression controllers are designed after the MDAO process, and it is found that the optimal control designs have significantly higher gain and phase margins. As a result, the optimal control designs yield higher robust closed-loop flutter speed as compared with the weight-minimized design.

Weight optimization of a composite wing-panel with flutter stability constraints by ply-drop

The existing approach in aircraft wing design optimizes the structure for strength and buckling design criteria followed by a flutter stability check, which leads to design that may not be optimal. This study proposes the flutter stability as an integral of weight optimization by a two-step procedure. Step 1 comprises series of flutter and static analyses of finite element (FE) models with different weapon configurations and aerodynamic loads, which give limiting values of wing tip deflection and wing twist as flutter constraints. Step 2 focuses on weight optimization of the laminate for strength and stiffness design parameters along with the flutter constraints. The algorithm minimizes structural weight by ply drop, which is based on evaluation of the fitness value of laminates generated by a stochastic operator. The ply drop design algorithm is applied to optimize the FE model of a fourth-generation fighter aircraft wing box with three representative aerodynamic loads and three weapon configurations. The application evolved optimal laminate with seamless and symmetric plies, which has 35% lesser weight compared with the initial model having quasi-isotropic laminates for given strength and flutter stability design requirement. The application of genetic algorithm (GA) to get an initial laminate instead of quasi-isotropic laminates further improved the design by 2.5% weight reduction.

Multi-objective topology optimization and structural analysis of periodic spaceframe structures

Reduction of structural weight provides significant benefits in many engineering applications. While methods to optimise structural shape and topology of both continuous solids and discrete frame structures have existed for a while, the advent of additive layer manufacturing processes has enabled more complex geometries to be feasible. In this paper, a periodic spaceframe structure is designed for minimum mass and maximum effective flexural and torsional rigidities. A method of parametrising the spaceframe through its constituent unit cells is proposed, and Genetic Algorithm (GA) multi-objective optimisation is used to optimise its topology, size and geometry as a generic structure. The superior performance of the topology optimised periodic spaceframe is highlighted in terms of structural rigidity, large deformation capability, buckling and vibrational modal analysis in compare to equivalent beam structures of identical weight and comparable domain. The results show that the proposed method can effectively generate lightweight substitute structures of great mechanical performance in many beam structures applications, such as: aircraft wing spars. The periodic spaceframe is applied into a conventional aircraft wing structure to demonstrate the possibilities of promoting weight saving in the design of civil aircraft wings.

Massively Multipoint Aerodynamic Shape Design via Surrogate-Assisted Gradient-Based Optimization

Multipoint aerodynamic design optimization involves no more than tens of flight conditions, which cannot thoroughly represent the actual demand. A comprehensive evaluation of the performance may consider hundreds or even thousands of flight conditions, and this leads to a massively multipoint optimization problem. Existing optimization methods are inefficient in such cases. This paper presents a surrogate-assisted gradient-based optimization architecture that efficiently solves massively multipoint design problems. To avoid the curse of dimensionality, surrogate models are constructed only in the low-dimensional space spanned by flow condition variables. With the aerodynamic functions and gradients computed by surrogate models, efficient gradient-based optimization is performed to find the optimal design. To ensure convergence, an adaptive sampling criterion is proposed to refine the surrogate models. In a transonic aircraft wing design case, the results show that the optimal design found by the proposed method with 342 missions yields a fuel burn reduction by a factor of two as compared to a regular multipoint optimal design. This work highlights the demand and provides an efficient way to conduct massively multipoint optimization in aircraft design.

Design and Computational Fluid Dynamic Analysis of a Medium Haul Commercial Aircraft Wing and Fuselage

Medium haul commercial aircrafts are used by airliners for medium range flights which includes domestic and international routes, below 4000 km but not less than 1500 km. These are widely used type of aircrafts for airliners. It is a very challenging process to design such an aircraft and there are a lot of processes and parameters which need to be assessed before finalizing a design. The aircraft is designed to seat a hundred passengers and one of the main requirements of such medium haul aircrafts is that they are designed to carry the heavy loads for longer durations and yet provide a smooth flying experience. The design aspects include the selection of airfoil and engines. The airfoil selected has high lift capabilities and has a gentle stall quality providing for a perfect fit for this category of aircraft and the fuselage has been analysed in order to withstand the various aerodynamic forces that the aircraft might endure during flight. The design of the Wing was performed on CATIA V5,the design of the fuselage was performed on SOLIDWORKS Inc. and the analysis of the wing and fuselage were performed on ANSYS R19.2(Student Version).The design is said to provide better lift capabilities with the help of the airfoil chosen which could provide for a better performance on modern day aircrafts.

Multidisciplinary design optimization of aircraft wing using commercial software integration

In this paper, a fully automated framework dedicated to the high-fidelity multidisciplinary design optimization of aircraft wing is developed. This design framework integrates a set of popular commercial software using their programming/scripting capabilities. It goes through geometric modeling in SIEMENS NX, aerodynamic meshing in ICEM CFD, flow solution using ANSYS FLUENT, structural finite element modeling in MSC.PATRAN and structural sizing in MSC.NASTRAN. By adopting a parametric modeling methodology, the structural and aerodynamic metrics reflecting the wing performance can be evaluated given a description of its shape and dimensions. In order to overcome the high cost of simulation models and allow the efficient solution of high-fidelity optimization problems, a surrogate-based optimization strategy is adopted. The reliability of the proposed approach is investigated through its application to the design of a high-speed passenger aircraft wing. The optimization objective is to maximize the aircraft range, given by the Breguet equation, while maintaining the lift coefficient and the structural safety. The case study results in a 8.9% increase in the range by considering shape and structural design variables.

Reducing Wing Observability to Radar using Microserrations at the Leading Edge

Serrations are found in nature on the leading edge (LE) of bird wings and whale flippers. These serrations reduce flight noise and improve aerodynamic performance. This has inspired LE serrations to be incorporated in the design of aircraft wings and turbine blades. LE of wings can contribute significantly to observability of aircraft by radar due to LE diffraction of horizontally polarized incident electromagnetic (EM) waves. Serrations at the wing LE can also be used to reduce observability to radar under such circumstances. In the present study, the method of equivalent currents is used to analyse the effect of microserrations on an infinitesimally thin metallic delta wing. It is shown that microserrations at the wing LE can be effectively used to control backscatter due to diffraction of EM waves at the wing LE. LE serrations, in general, work by introducing a randomness in the interaction of wing LE with incident fluid flow or EM field.